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G Programming Reference Manual

1. Error Messages Descriptions Un bundle By Name Empty The input cluster wired to the Bundle By Name cluster or some components are function is either empty or has some components unnamed that are not labeled Unit bad unit syntax The text in the node is not a legal unit expression A is placed immediately before the unrecognizable character If you encounter messages that are not self explanatory and are not listed in this chapter contact National Instruments Correcting Broken VI Range Errors A range error indicator appears in place of the Run button in the following circumstances Range Error indicator You configured a control on a subVI to stop execution when it receives an out of range value through the Data Range option of the control and the control receives such a value You configured an indicator on a subVI to stop execution when it tried to return an out of range value to a calling VI and the indicator attempted to return such a value An operator enters an out of range value into a control that you set to stop execution on error as long as that the VI is not running at the time You can determine which control or indicator is out of range by its change in appearance as shown in the following illustration G Programming Reference Manual 4 14 National Instruments Corporation Chapter 4 Executing and Debugging Vis and SubVIs Note A VI or subVI can pass out of range
2. National Instruments Corporation 15 3 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators The first data type that the XY graph accepts is a cluster containing an x array and ay array The following diagram illustrates how you can create this kind of data cluster of x and y The second data type is an array of points where a point is a cluster of an x value and a y value The following diagram illustrates how you can create this kind of data array of cluster of x and y values G Programming Reference Manual 15 4 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators Plotting Multiplot Graphs You can display multiple plots on a single waveform or XY graph For the most part you use arrays of the data types described in the previous section to describe multiple plots for display in a single graph Because G does not accept arrays of arrays in a case where creating an array of a single plot data type produces an array of arrays you can use either 2D arrays or arrays of clusters of arrays Waveform Graph Data Types The multiplot waveform graph accepts five data types which are described in the following paragraphs The first data type that a multiplot graph waveform accepts is a two dimensional array of values where each row of the data is a single plot The graph interprets this data as points with the points starting at x 0 and incremente
3. 3_ Visible FALSE Disabled Attribute You can control whether a user has access to an object by implementing the Disabled Attribute A value of zero enables an object so that the user can operate it A value of one disables the object preventing operation A value of two disables and grays out the object Ee Disabled You can disable user access to a digital control The control does not change appearance when disabled in the first example In the second National Instruments Corporation 20 7 G Programming Reference Manual Chapter 20 Attribute Nodes we example the user access to the digital control is disabled and is grayed out digital contral Ae datal control Key Focus Attribute With the Key Focus Attribute you can make a control be the key focus or check to see if it currently has the focus A control that has key focus behaves as though you tabbed over to that control to make it active On most controls you can enter values into the control by typing them with the keyboard You also can set the key focus on the front panel by pressing the lt Tab gt key while in run mode or by pressing the hot key associated with the control assigned by using the Key Navigation option You can make a digital control the key focus Then you can enter a new value in the control without selecting it with the mouse digital contral digital control ak ki
4. National Instruments Corporation 8 3 G Programming Reference Manual Chapter 8 Introduction to Front Panel Objects If you pop up on a control while a VI is running you can change only the value of a control While running a VI you cannot change most characteristics of a control such as its default value or description Replacing Controls The Replace option of the pop up menu of an object displays the Controls palette from which you can choose a control or indicator to take the place of the current item on the front panel Use Replace when you want to choose a different style of control but do not want to lose all of the editing options you have selected for the control up to that point Selecting Replace from the pop up menu preserves as much information as possible about the original control such as its name description default data dataflow direction control or indicator colors size and so on However the new control keeps its own data type Wires from the terminal of the control or local variables remain connected on the block diagram The more similar the control is to the one being replaced the more the original characteristics can be preserved As an example the following illustration shows a slide being replaced by a different style of slide speed settings 100 s0 Change to Indicator Find Terminal Show ema Ce ke Data Operations Boolean ema ca Create Attribute Node
5. See examples of intensity charts in general examples general graphs intgraph 1lb Intensity Chart Options The intensity chart shares many of the optional parts of the other charts most of which can be shown or hidden from the Show submenu of the graph pop up menu These options include a palette you use to change scaling and format options while the VI is running In addition because the intensity chart has a third dimension color a scale similar to a G Programming Reference Manual 15 38 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators color ramp control is used to define the range and mappings of values to colors Following is a picture of a graph showing all of these optional components except for the Cursor palette which is discussed in the Graph Cursors section of this chapter z scale color scale y scale x and y grids scale palette scrollbar Intensity charts have many options you can use to customize your data display The intensity chart pop up menu is shown below in the following illustration Change to Control Find Terminal Show gt Data Operations gt Create gt Key Navigation Replace gt x Scale gt Y Scale b Z Scale gt Transpose Array Chart History Length National Instruments Corporation 15 39 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators Most of these options are identical to
6. G Programming Reference Manual oa gt On _ an Part Number 321296A 01 October 1996 Copyright 1992 1996 National Instruments Corporation All rights reserved Li Internet Support GPIB gpib support natinst com DAQ dag support natinst com LabVIEW lv support natinst com BridgeVIEW bv support natinst com Lookout lookout support natinst com E mail info natinst com FTP Site ftp natinst com Web Address http www natinst com Bulletin Board Support BBS United States 512 794 5422 or 800 327 3077 BBS United Kingdom 01635 551422 BBS France 01 48 65 15 59 FaxBack Support 512 418 1111 Os Telephone Support U S Tel 512 795 8248 Fax 512 794 5678 Q lt C gt International Offices Australia 03 9879 5166 Austria 0662 45 79 90 0 Belgium 02 757 00 20 Canada Ontario 905 785 0085 Canada Qu bec 514 694 8521 Denmark 45 76 26 00 Finland 90 527 2321 France 01 48 14 24 24 Germany 089 741 31 30 Hong Kong 2645 3186 Israel 03 5734815 Italy 02 413091 Japan 03 5472 2970 Korea 02 596 7456 Mexico 95 800 010 0793 Netherlands 0348 433466 Norway 32 84 84 00 Singapore 2265886 Spain 91 640 0085 Sweden 08 730 49 70 Switzerland 056 200 51 51 Taiwan 02 377 1200 U K 01635 523545 National Instruments Corporate Headquarters 6504 Bridge Point Parkway Austin TX 78730 5039 Tel 512 794 0100 Important Information Warranty Copyright Trademarks
7. show Replace Create Creat Control Crate Indicator elink To Sub Open Front Panel Show Vl Hierarchy You either can write to a global variable or read from a global variable Writing to a global variable means the value of the global is changed reading from a global means the global is accessed as a data source If you want to write to or read from a global select the Change to Write Global or the Change to Read Global option of the global variable pop up menu After you define a global variable you can place it in other VIs using Functions Select a VI If you select a global variable from the file dialog box G places the global variable node on the diagram You also can clone copy and paste or drag copy a global from the Hierarchy window Local Variables With a local variable you can write or read one of the controls or indicators on the front panel of your VI Writing to a local variable has the same result as passing data to a terminal except that you can write to it even though it is a control or read from it even though it is an indicator Also you can have any number of local variable references National Instruments Corporation 21 3 G Programming Reference Manual Chapter 21 Global and Local Variables to a particular front panel control with some in write mode and others in read mode In effect with a local variable reference you can use a front panel control as both an input and an output
8. Selectively Presenting Users with Options As users make selections you might want to present them with other options There are three possibilities 1 One option is to use pop up subVIs You can create subVIs that have the options you want to present to the user By using the Show Front Panel when Called and Close Afterwards if Originally Closed options of VI Setup Execution Options when you create your subVI you can have one of these subVIs open when called 2 Another method for presenting options is to use the Visible option of Attribute Nodes to selectively show and hide controls 3 The third method for presenting options is to use the Disabled option of Attribute Nodes to disable controls selectively When a control is disabled the user cannot change the value Reading Graph Cursors Programmatically You can use attributes to access information from one plot on a multi plot graph or one thumb on a multi thumb slide but you must indicate which item is being operated on The multiple cursors on a graph are a good example of an attribute that must be activated before it can be accessed from the diagram The following block diagram shows a VI that displays data in a graph and programmatically reads the position of graph cursors G Programming Reference Manual 20 14 National Instruments Corporation Chapter 20 Attribute Nodes Working through a While Loop the VI first activates the Min Value cursor and reads its nu
9. Cluster elements cannot be array elements If you have a cluster of N dimensional arrays that you want to convert to an N 1 dimensional array you must unbundle the cluster elements with the Unbundle function and wire them to a Build Array function The Cluster To Array function is useful when you want to group a set of front panel controls in a particular order within a cluster but you also G Programming Reference Manual 14 32 National Instruments Corporation Chapter 14 Array and Cluster Controls and Indicators want to process them as an array on the block diagram as shown in the following illustration Replacing Cluster Elements Sometimes you want to replace or change the value of one or two elements of a cluster without affecting the others You can do this by unbundling a cluster and wiring the unchanging elements directly to a Bundle function along with the replacement values for the other element The following example shows a more convenient method This example computes the number of hours until New Year using the date time cluster Because the cluster input terminal middle terminal of the Bundle function is wired the only element input terminals that need to be wired are those with replacement values National Instruments Corporation 14 33 G Programming Reference Manual Chapter Graph and Chart Controls and Indicators This chapter describes how to create and use the graph and chart indicators
10. Table 19 1 Table 19 2 Table A 1 Table A 2 Error MEeSSaS eS e arrra e a eaer ELEA sedosse ase EA EEA eE ERRES 4 11 Breakpoint Placements sac cstiveseaeeh e e E A E ES Ei 4 27 Range Options of Floating Point Numbers s essseessssereeeereerereererreseereee 9 6 Base Units rra err son seca vss rapa eas aeni a EE s aE EEEa a EEE ISS 9 28 Derived Units with Special Names sessesessseesrssesrsreererrsreerrsreresrererrssen 9 28 Additional Units in Use with SI Units sseesssseesesseeeesseeseereseersseeresreresee 9 29 CGS UNS inea e reaa to ae e Hehe a AA aes eS 9 30 Other UN Serai r r aa rerea re eena e r e S EE Eai 9 30 GV CodeS scant ere ara ee a antes a TEE E E EEE Ean 11 4 G Control and Indicator Terminal Symbols ssssssesseseeseeseeesseeessereseeeee 16 2 Formula Node Functions ss esssseeeseseseseeeersreersreeresreesrsserrrsreersresesresreeesee 19 5 Formula Node ErrOfS sieer serieei anoeie eieaa o DEE E eE 19 9 Scalar Numeric Data Types 00 0 cee ce ceseeeeceeeeeeceeeeeeeeeeeseecaeesaecaeesseenees A 8 Non Numeric Data Types 00 0 ceeceseeseceeceseceeceseseeeesessaeeseesaesnaeeaees A 10 G Programming Reference Manual XX National Instruments Corporation The G Programming Reference Manual discusses how to create edit and execute virtual instruments VIs using the G programming language This manual explains the front panel and block diagram numeric Boolean string array and cluster controls and i
11. You can copy cut and paste data using the Copy Data Cut Data and Paste Data options in the Data Operations submenu of the pop up menu If you cut any row or rows of data all rows below it move up as shown in the top portion of the following illustration If you cut any column of data all columns to the right scroll left as shown in the bottom portion of the illustration G Programming Reference Manual 11 8 National Instruments Corporation Chapter 11 String Controls and Indicators Tee peee afasia H esje CEOE eL MH i After cutting row rape pee ek ee pafzjeH festre H mepes feee E A Selecting a column After cutting column To show a selected area of data you can turn the option on or off by selecting or deselecting Data Operations Show Selection The row and column headings of a table are not part of the table data Table headings are a separate piece of data and you can read and set them using the Attribute Node The table is the same as a two dimensional array of strings as far as the block diagram is concerned Because of this string functions can manipulate tables See the Online Reference Function and VI Reference String Functions topic for information on using these functions National Instruments Corporation 11 9 G Programming Reference Manual Chapter Path Controls and Indicators and Refnums lt 12 This chapter describes how to use file path controls and refnums whi
12. option You use this option to associate a keyboard key combination with a control When a user enters that key combination while running the VI G acts as though the user had clicked on that control The associated control becomes the key focus If the control is a text control any existing text within that control is highlighted ready for editing If the control is a Boolean control the state of the button is toggled Note The Key Navigation option is disabled for indicators because you cannot enter data into an indicator You also can use the Key Navigation option to indicate whether a control should be included when the user tabs from control to control while running National Instruments Corporation 8 5 G Programming Reference Manual Chapter 8 Introduction to Front Panel Objects You can use the Key Navigation option to associate function keys with various buttons that control the behavior of a panel You can use it to define a default button for VIs that behave like a dialog box so that pressing the lt Enter gt Windows and HP UX or lt Return gt Macintosh and Sun key becomes the same as clicking on the default button If you associate the lt Enter gt or the lt Return gt key with a dialog box button G automatically draws that button with a special thick border around it as shown in the following illustration There are two important things to know about the lt Enter gt or the lt Retur
13. Cluster Assembly G has three functions for assembling or building clusters The Bundle and Bundle By Name functions assembles a cluster from individual elements or replaces individual elements with elements of the same National Instruments Corporation 14 23 G Programming Reference Manual Chapter 14 Array and Cluster Controls and Indicators PP Bundle function bP Bundle By Name function type The Array To Cluster function converts an array of elements into a cluster of elements Bundle Function The Bundle function which you obtain from the Array amp Cluster palette of the Functions palette appears on the block diagram with two element input terminals on the left side You can resize the icon vertically to create as many terminals as you need The element you wire to the top terminal becomes element 0 in the output cluster the element you wire to the second terminal becomes element 1 in the output cluster and so on As you wire to each input terminal a symbol representing the data type of the wired element appears in the formerly empty terminal shown in the following illustration You must wire all the inputs that you create In addition to input terminals for elements on the left side the Bundle function also has an input terminal for clusters in the middle as shown in the following illustration You use this terminal to replace one or more elements of an existing cluster wire without affecting the other ele
14. G Programming Reference Manual 26 2 National Instruments Corporation Chapter 26 Performance Issues Viewing the Results You can choose to display only parts of the information in the table Some basic data is always visible but you can choose to display the statistics details and if enabled memory usage by checking or unchecking the appropriate checkboxes in the Profile window Performance information also is displayed for Global VIs However this information sometimes requires a slightly different interpretation as described in the category specific sections below Performance data for subVIs when called from a specific VI can be viewed by double clicking on the name of a VI in the tabular display When you do this new rows appear directly below the name of the VI containing performance data for each of its subVIs When you double click on the name of a Global VI new rows appear for each of the individual controls on its front panel You can sort the rows of data in the tabular display by clicking in the desired column header The current sort column is indicated by a bold header title Timings of VIs do not necessarily correspond to the amount of elapsed time that it takes for a VI to complete This is because multi threaded execution system can interleave the execution of two or more VIs Also there is a certain amount of overhead taken up that is not attributed to any VI such as the amount of time taken by a user to r
15. G Programming Reference Manual 3 4 National Instruments Corporation Chapter 3 Building SubVIs Defining Connector Terminal Patterns You send data to and receive data from a subVI through the terminals in its connector pane You define connections by choosing the number of terminals you want for the VI and by assigning a front panel control or indicator to each of those terminals Only the controls and indicators you use programmatically by wiring to the subVI require terminals on the connector pane If the connector for your VI is not displayed already in the upper right corner of the front panel choose Show Connector from the icon pane pop up menu as shown in the following illustration The block diagram does not have a connector pane ji m 1 UI Setup Edit Icon Show Connector Bast Gsan yi pipip p Pearess Flip Horicon tel Pi Laiiic nd epagne RH Tornnignis Eikecepprpag E Fidiy Peer yyriyecei This Gariya fin Es The connector replaces the icon in the upper right corner of the front panel G selects a terminal pattern for your VI with as many terminals on the left of the connector pane as controls on the front panel and as many terminals on the right of the connector pane as indicators on the front panel Each of the rectangles on the connector represents a terminal area and you can use them either for input to or output from the VI If you want to use a different terminal pattern for your VI you can
16. National Instruments Corporation Chapter 2 Building Vis Note If you place a label or any other object over partially covering a control or indicator it slows down screen updates and might make the control or indicator flicker To avoid this problem do not overlap a front panel object with a label or other object You can copy the text of a label by selecting it with the Labeling tool Double click on the text with the Labeling tool to highlight the section you want Triple click on the text to highlight the entire label You also can drag the Labeling tool across the text to highlight it When the text is selected choose Edit Copy to copy the text onto the Clipboard Now you can highlight the text of a second label Select Edit Paste to replace the highlighted text in the second label with the text from the Clipboard To create a new label with the text from the Clipboard click on the screen with the Labeling tool where you want the new label positioned Then select Edit Paste When you create a control or indicator on the front panel a blank owned label accompanies it waiting for you to type the name of the new control or indicator The label disappears if you do not enter text into it before clicking on another area with the mouse You can show the label again by popping up on the control or indicator and selecting Show Label Structures and functions come with a default label which is hidden until you show it You can edi
17. The scale submenu options apply to the scale for the slide only The scale pop up menu is shown in the following illustration Marker Spacing Hi Merker Text Labels kaiaia Mark ar Format f Precision Style Mapping b The Marker Spacing option is discussed in the section Scale Markers 9 14 National Instruments Corporation Chapter 9 Numeric Controls and Indicators The Format amp Precision option functions as described in the Format and Precision of Digital Displays section of this chapter The Style option shows you the palette shown in the following illustration You can display a scale with no tick marks or no scale values or you can hide the scale altogether o f The Mapping item shows you the option of linear or logarithmic scale spacing as shown in the following illustration Linear Logarithmic If you change to Logarithmic spacing and the low scale limit is less than or equal to 0 the limit automatically becomes a positive number and G revalues other markers accordingly Keep in mind that scale options including the mapping functions are independent of the slide data range values which you change with the Data Range pop up option If you want to limit your data to logarithmic values you need to change the data range to eliminate values less than or equal to zero Scale Markers The scale of a numeric control or indicator has two or more markers which are labels that show the
18. Windows lt command b gt Macintosh lt met a b gt Sun or lt Alt b gt HP UX Often this fixes a broken VI To find out why a VI is broken click on the Broken Run button An Error List window appears listing all the errors This window is shown Broken run in the following illustration button UI List Untitled 1 Show Warnings J Block Diagram Errors Absolute Value contains unwired or bad terminal Block Diagram warnings BDConstant unwired block diagram constant Choose a Vl from the list of names to see its errors Click on any error in the list to display more details about it here Double click on any front panel or block diagram error ar click on the Find button to highlight the object Pind You also can access this box by clicking on the Warning button of a VI or by selecting Windows Show Error List The Warning button for a VI is only visible if the VI has a warning such as overlapping Warning objects and you have checked the Show Warnings option in the Error button List window You can use the Preferences dialog box to configure G to show warnings by default To locate a particular error double click on the text that describes it G shows the error by bringing the relevant window to the front and G Programming Reference Manual 4 10 National Instruments Corporation Chapter 4 Executing and Debugging Vis and SubVIs highlighting the object causing the error You also can view error
19. Windows lt opt ion gt Macintosh lt met a gt Sun or lt Alt gt HP UX key while double clicking on a subVI brings its block diagram to the front Execution Highlighting For debugging purposes it is helpful to view an animation of the execution of the VI block diagram To use this feature click on the Hilite Execution button The button changes its appearance Click on this button at any time to return to off on normal view mode You commonly use execution highlighting in Hilite Execution button conjunction with single step mode to gain an understanding of how data flows through nodes Highlighting greatly reduces the performance of a VI With execution highlighting the movement of data from one node to another is marked by bubbles moving along the wires Additionally in National Instruments Corporation 4 21 G Programming Reference Manual Chapter 4 Executing and Debugging Vis and SubVIs single stepping the next node blinks rapidly as shown in the following illustration sequence G Programming Reference Manual 4 22 National Instruments Corporation Chapter 4 Executing and Debugging Vis and SubVIs When you are single stepping through a subVI with the Hilite Execution button on an execution glyph on the subVI icon of the block diagram indicates which VIs are running and which are waiting to run a E running waiting to run Block Diagram The Hierarchy window displays whether a VI is paused an
20. You can think of this as a placeholder for the actual unit When the VI is called G substitutes the units you pass in for all occurrences of x in that VI The x place holder always gets passed a unit that is expressed in base units for example meters meters sec not feet inches and so on A polymorphic unit is treated as a unique unit It is not convertible to any other unit and propagates throughout the diagram just as other units do When it is connected to an indicator that also has the abbreviation 1 the units match and the VI can compile 1 can be used in combinations like any other unit For example if the input is multiplied by 3 seconds and then wired to an indicator the indicator must be 1 s units If the indicator has different units the block diagram shows a bad wire If you need to use more than one polymorphic unit you can use the abbreviations 2 3 and so on A call to a subVI containing polymorphic units computes output units based on the units received by its inputs For example suppose you create a VI that has two inputs with the polymorphic units 1 and 2 that creates an output in the form 1 2 s If a call to the VI receives inputs with the unit m s to the 1 input and kg to the 2 input the output unit is computed as kg m s 2 Suppose a different VI has two inputs of 1 and 1 s and computes an output of 1 2 If a call to this VI receives inputs of m s to the 1 input and m s 2 to the 1 s in
21. numeric range checking 9 7 to 9 9 Coerce option 9 7 correcting invalid values 9 8 to 9 9 Ignore option 9 7 Suspend option 9 8 National Instruments Corporation l 41 Index 0 object descriptions creating 2 26 to 2 27 Object Pop up Menu tool 2 5 Objects in vi 1ib option 3 25 objects unavailable in student edition 7 12 Occurrence RefNum 12 4 one dimensional arrays 14 3 14 10 Online Reference command 1 9 Open Front Panel option 3 21 Open Front Panel when loaded option 6 6 Operate menu Change to Customize Mode 22 5 to 22 6 Change to Edit Mode 22 5 to 22 6 Clear Log File Binding 4 6 Data Logging submenu 4 5 to 4 6 Log at Completion 4 6 Print at Completion 5 7 Retrieve 4 6 Run 4 1 Stop 4 4 Suspend when Called 4 29 Operating tool 2 5 9 2 lt option gt key bringing subVI block diagram to front 4 21 changing Icon Editor tools to dropper 3 4 cloning Attribute Nodes 20 4 cloning objects 2 13 creating new scale marker 9 17 to 9 18 lt option click gt executing Show VI Hierarchy action 3 21 resizing working space 2 24 untacking last tack point note 17 3 lt option Return gt embedding newlines 7 10 Original Size option 22 11 Others option 3 25 overlaid plots 15 28 to 15 29 owned labels controls or indicators 2 15 definition 2 14 G Programming Reference Manual Index P Page Breaks Between Sections option 5 4 page layout setting programmatically 5 8 Page Setup option
22. 17 17 structure wiring problems assigning more than one value to sequence locals 18 22 failing to wire tunnels 18 22 overlapping tunnels 18 23 to 18 24 wiring from multiple frames of Sequence Structures 18 24 to 18 25 wiring underneath rather than through structures 18 25 to 18 26 tack points 17 3 tip strips 17 4 wire stretching 17 5 to 17 6 wire stubs 17 4 wiring connection information in Help window 17 5 wiring problems dimension conflict 17 12 element conflict 17 12 faulty connections 17 11 listing errors 17 11 to 17 12 loose ends 17 14 multiple wire sources 17 13 no wire sources 17 13 unit conflict 17 12 wire cycle 17 15 wire stubs 17 4 17 14 wire type conflict 17 12 wiring guides showing 17 11 Wiring tool disabled in Control Editor 22 7 hot spot 17 1 purpose and use 2 5 word integer numeric data storage format A 3 G Programming Reference Manual l 58 X X button 8 9 14 22 X Scale Formatting dialog box 15 14 to 15 16 Format amp Precision option 15 16 Grid Options option 15 15 Mapping Mode option 15 15 Scale Style option 15 15 Scaling Factors option 15 15 to 15 16 X Scale submenu 15 13 15 40 XY graphs See waveform and XY graphs Y Y Scale submenu 15 13 15 40 Z Z Scale Info Attribute Color Array 15 40 High Color 15 40 Low Color 15 40 zooming options graph indicators 15 17 to 15 19 National Instruments Corporation
23. 5 1 palettes See also specific palettes customizing See Controls and Functions palettes customizing keeping open note 2 2 pop up palettes 2 3 removing VIs from palette with Delete Item option 7 29 temporary copies 2 3 Palettes editor 7 26 to 7 29 creating subpalettes 7 27 to 7 29 Edit palettes dialog box 7 26 to 7 27 Insert Submenu dialog box 7 27 to 7 29 moving subpalettes 7 29 Panel Order option 8 8 to 8 9 illustration 8 9 questions about B 13 X button 8 9 panning options for graph indicators 15 16 to 15 18 parallel diagrams 26 8 to 26 9 parts of controls controls as parts 22 15 to 22 17 cosmetic parts 22 9 to 22 14 adding to custom controls 22 17 to 22 18 with independent pictures 22 12 to 22 14 with more than one picture 22 11 to 22 12 scale parts 22 15 text parts 22 14 to 22 15 Password Display option 11 5 Paste command 2 12 Paste Data option 11 8 Path amp Refnums palette 12 2 path constant 16 7 path controls and indicators 12 1 to 12 2 illustration 12 1 Not a Path symbol 12 2 G Programming Reference Manual Path symbol 12 2 purpose and use 12 2 Path Preferences dialog box 7 2 to 7 6 format of pathnames note 7 3 illustration 7 2 library temporary and default directories 7 3 to 7 4 removing paths with Remove button 7 6 VI search path 7 5 to 7 6 Path symbol 12 2 paths data storage formats A 5 flattened data A 13 Patterns option terminal patterns 3 6 Pause bu
24. 9 10 to 9 11 graph indicators 15 15 to 15 16 timer using default 7 7 to 7 8 tip strips showing tip strings over terminals 7 11 toggling display 7 22 wiring block diagrams 17 4 toolbar hiding 6 6 tools 2 4 Tools palette changing between tools 2 5 illustration 2 4 purpose and use 2 4 temporary copies 2 4 tools available in palette 2 5 Top Edges alignment 2 12 transparent labels selecting 7 10 transparent objects 2 24 to 2 25 Transpose Array option graph pop up menu 15 5 15 11 intensity graph 15 28 waveform chart pop up menu 15 24 tree form of data storage A 12 troubleshooting See questions about G tunnels definition 16 12 17 2 18 3 moving 17 9 wiring problems failing to wire tunnel in all cases of Case Structure 18 22 overlapping tunnels 18 23 to 18 24 G Programming Reference Manual 1 54 two dimensional arrays 14 3 to 14 10 definition 14 3 displaying in single element or tabular form 14 9 to 14 10 example 14 3 interpreting array index display 14 8 to 14 9 type checking of units 9 33 to 9 34 type definitions 22 19 to 22 22 automatic updating 22 21 cluster type definitions 22 22 creating 22 20 definition 22 19 disconnecting 22 22 including in Hierarchy window 3 19 matching data types 22 19 saving 22 20 searching for 22 22 strict type definitions 22 19 to 22 20 updating 22 21 using 22 20 to 22 21 Type Defs option 3 25 type descriptors array A 11 cluster A 11 to A
25. 9 4 Enter button for replacing old values 9 2 format and precision of digital displays 9 9 to 9 11 illustration 9 2 incrementing and decrementing 9 2 to 9 3 numeric range checking 9 7 to 9 9 Operating tool 9 2 purpose and use 9 2 to 9 3 range options 9 6 to 9 7 valid values 9 2 rotary numeric controls and indicators 9 21 to 9 23 illustration 9 21 purpose and use 9 22 to 9 23 National Instruments Corporation slide controls and indicators 9 12 to 9 20 filled and multivalued slides 9 20 illustration 9 12 operating sliders 9 13 overview 9 12 scale markers 9 15 to 9 18 Scale pop up menu 9 14 to 9 15 slide pop up menu options 9 14 slide scale 9 14 to 9 19 text scale 9 18 to 9 19 unit types 9 26 to 9 35 additional units in use with SI units table 9 29 to 9 30 base units table 9 28 CGS units table 9 30 derived units with special names table 9 28 to 9 29 entering units 9 31 to 9 33 other units table 9 30 to 9 31 polymorphic units 9 35 showing unit label 9 26 to 9 27 strict type checking and units 9 33 to 9 34 numeric data storage formats A 1 to A 3 byte integer A 3 double A 2 extended A 1 to A 2 long integer A 3 single A 2 word integer A 3 numeric data types 23 6 Numeric formatting graph indicators 15 16 numeric keypad on Sun keyboards supporting 7 10 Numeric palette digital control and digital indicator 8 3 illustration 2 2 9 1 selecting objects 2 2
26. An additional method is using the LabWindows CVI Function Panel converter to convert an instrument driver written in LabWindows CVI Executing Other Applications from within Your Vis You can execute other applications from within your VIs The methods are different on Windows and UNIX than on the Macintosh Windows UNIX You use System Exec to execute other applications from within your VIs You can use the simple System Exec VI from the Functions Communication palette to execute a command line from your VI The command line can include any parameters supported by the application you plan to launch If you can access the application through TCP IP or DDE in Windows you might be able to pass data or commands to the application See the reference material for the application you plan to use to see the extent of its communication capability If you are a LabVIEW user you also can refer to Chapter 1 Communication Applications in LabVIEW of the LabVIEW Communications VI Reference Manual for more information on techniques for using networking VIs to transfer information to other applications Macintosh You use Apple Event VIs to execute other applications from within your VIs Apple Events are a Macintosh specific protocol through which applications can communicate with each other They can be used to send commands between applications You also can use them to launch other applications If you are a LabVIEW user see Chapter 1 Commu
27. Chapter Wiring the Block Diagram This chapter explains how to connect terminals on the block diagram by wiring them together Wiring Techniques You use the Wiring tool to connect terminals The cursor point or hot spot of the tool is the tip of the unwound wire segment as shown in the following illustration wiring cursor hot spot _a gt Fy The symbol to the left represents the mouse In the wiring illustrations in this chapter the arrow at the end of this mouse symbol shows what area to click on and the number printed on the mouse button indicates how many times to click on it To wire from one terminal to another click the Wiring tool on the first terminal move the tool to the second terminal and then click on the second terminal as shown in the preceding illustration It does not matter which terminal you click on first The terminal area blinks when the hot spot of the Wiring tool is correctly positioned on the terminal Clicking on that terminal connects a wire to it When you have made the first connection the spool icon draws a wire as you move the cursor National Instruments Corporation 17 1 G Programming Reference Manual Chapter 17 Wiring the Block Diagram across the diagram as if the wire were unwinding from a spool You do not need to hold down the mouse button To wire from an existing wire perform the operation just described starting or ending the operation on the ex
28. If an object is hidden completely by another object G generates a warning to indicate that all objects are not visible For example if a terminal is hidden under the edge of a structure or tunnels are on top of each other a warning message is placed in the Error List window Warnings do not prevent you from running a VI they are intended to help you debug potential problems in your programs Debugging Features wu Pause button Step Over button The following debugging features are discussed in this section e Single stepping through a VI to observe each execution step e Highlighting execution to watch the data flow as it occurs e Using a probe to display data e Setting breakpoints to pause execution so that you can single step probe wires to see their data or edit indicators e Suspending execution to edit indicators to control the number of times to execute or to go back to the beginning of the VI Single Stepping through Vis For debugging purposes you might want to execute a block diagram node by node This form of execution is called single stepping While executing a VI you can start single stepping by clicking on the Pause button If you have not yet started executing a VI you can start single stepping by pressing the Start Single stepping button From single stepping you can return to normal execution at any time by clicking on the Pause button While the VI is running in single step mode you can press
29. If you prefer you can specify marker locations anywhere on the x or y National Instruments Corporation 15 13 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators scale This is useful for marking a few specific points on a graph such as a set point or threshold If you want non uniform marker distribution choose X or Y Scale Marker Spacing Arbitrary Markers from the pop up menu for the scale After making this selection if you move the Operating tool over a tick mark the cursor changes to the double arrow cursor shown in the following illustration You can now create a new marker by dragging the existing tick mark with the lt Ctr1 gt Windows lt opt ion gt Macintosh lt met a gt Sun or lt Alt gt HP UX key selected or you can move the existing tick mark anywhere on the scale you want by dragging it You can add or delete a marker by popping up on the graph or the scale and selecting Add Marker or Delete Marker When a marker is created you can type a number in the marker to change its location G Programming Reference Manual 15 14 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators Formatting Click on Formatting to bring up the dialog box shown in the following illustration Scale Formatting Format and Precision Example s Decimal T Digits of Precsision Floating Point Notation D Scientific Nota
30. Normal Display 11 3 Password Display 11 5 Scrollbar 11 3 tables 11 6 to 11 9 copying cutting and pasting data 11 8 entering and selecting data tables 11 7 to 11 9 illustration 11 6 manipulating with string functions 11 9 resizing tables rows and columns 11 6 to 11 7 row and column headings 11 9 scrolling 11 7 to 11 8 Selection Scrolling option 11 8 showing selected area of data 11 9 string data type 23 7 String palette 8 3 strings data storage formats A 5 flattened data A 13 strip chart update mode 15 26 structures See also Case Structures For Loops Sequence Structures While Loops default labels 2 15 definition 16 11 18 1 deleting while preserving contents 2 13 efficiency considerations 26 28 to 26 36 avoiding complicated data types 26 30 to 26 32 global table of mixed data types 26 32 to 26 35 static global table of strings 26 35 to 26 36 G Programming Reference Manual Index examples located in examples 11b 18 1 icons for 18 2 overview 18 2 to 18 3 placing and sizing on block diagram 18 5 to 18 6 tunnels 16 12 types of 16 11 wiring problems assigning more than one value to sequence local 18 22 failure to wire tunnel in all cases of Case Structure 18 22 overlapping tunnels 18 23 to 18 24 removing structures without deleting contents 18 26 wiring from multiple frames of Sequence Structure 18 24 to 18 25 Structures palette 18 1 student edition objects unavailable 7 1
31. Prompt for comment when this VI is saved 6 4 Use History Defaults In Preferences Dialog 6 3 execution options 6 2 to 6 3 Close Afterwards if Originally Closed 6 2 illustration 6 2 Run When Opened 6 2 Show Front Panel When Called option 6 2 Show Front Panel When Loaded option 6 2 Suspend When Called 6 2 window options 6 4 to 6 6 Allow Run Time Pop Up Menu 6 5 Allow User to Close Window 6 5 Auto Center 6 5 Dialog Box option 6 5 Enable Log Print at Completion 6 6 Hilite lt Return gt Boolean 6 5 illustration 6 5 Show Toolbar 6 6 Size to Screen 6 5 VI Setup option 3 21 View menu Hierarchy window 3 18 to 3 19 Full VI Path in Label option 3 19 Horizontal Hierarchy option 3 18 illustration 3 18 Include Globals option 3 18 Include Type Defs option 3 19 Include VIs in vi 1ib option 3 18 G Programming Reference Manual 1 56 Redraw option 3 18 Show All VIs option 3 18 Vertical Hierarchy option 3 18 views VI n installing and changing 7 26 working with views 7 29 See also applications managing subVIs building See building VIs components 1 1 to 1 6 debugging See debugging VIs definition 1 1 editing See editing VIs executing See executing VIs finding 3 24 to 3 25 launching automatically B 14 to B 15 loading questions about B 10 to B 12 performance issues See performance issues portability issues 27 1 to 27 5 ease of porting between platforms 27 2 nonportable V
32. Secant Computes the secant of x radians 1 cos x sign x Sign Returns if x is greater than 0 returns 0 if x is equal to 0 and returns 1 if x is less than 0 sin x Sine Computes the sine of x radians sinc x Sinc Computes the sine of x divided by x radians sin x x sinh x Hyperbolic Sine Computes the hyperbolic sine of x in radians National Instruments Corporation 19 7 G Programming Reference Manual Chapter 19 Formula Nodes Table 19 1 Formula Node Functions Continued Function Corresponding G Description Function Name sqrt x Square Root Computes the square root of x tan x Tangent Computes the tangent of x in radians tanh x Hyperbolic Tangent Computes the hyperbolic tangent of x in radians x y x Computes the value of x raised to the y power Formula Node Syntax The Formula Node syntax is summarized below using Backus Naur Form BNF notation Square brackets enclose optional items lt assignlst gt lt outputvar gt lt aexpr gt lt assignlst gt lt aexpr gt lt expr gt lt outputvar gt lt aexpr gt lt expr gt lt expr gt lt binaryoperator gt lt expr gt lt unaryoperator gt lt expr gt lt expr gt lt expr gt lt expr gt lt expr gt lt inputvar gt lt outputvar gt lt const gt lt function gt lt arglist gt lt binaryoperator gt t gt
33. Show Digital Display to display the numeric value associated with the current item of a ring For every ring the item values above the insertion point increase by one to adjust for the new item For example if you insert an item after item 4 the new item becomes item 5 the previous item 5 becomes item 6 6 becomes 7 and so on If you insert an item before item 4 the new item becomes item 4 the previous item 4 becomes item 5 5 becomes 6 and so on G Programming Reference Manual 13 8 National Instruments Corporation Chapter 13 List and Ring Controls and Indicators Use the Remove Item command from the ring pop up menu to delete any item As with the add item commands the numeric values of the item adjust automatically If you set a ring indicator or control to a value smaller than zero or greater than the number of items included the control or indicator displays the first or the last item respectively Adding Picture Items to Rings A new Pict Ring or Text amp Pict Ring has one item with an empty picture display You must copy a picture to the Clipboard before you can import the picture into a Pict Ring When you have a picture on the Clipboard pop up on the Pict Ring and select Import Picture To add another picture copy it to the Clipboard then pop up on the Pict Ring and select Import Picture Before or Import Picture After as shown in the following illustration Change to Indicator Find Terminal Show Data Ope
34. Strict Type Definition Everything Must Match eee eeeeeeeeeeeeeeeeenes 22 19 Creating Type Definitions seesesseeeseierseseseessseerrsteresrertsresrerrsrentnsrnresrssrsssee 22 20 Using Type Definitions nnas e r ii Gores pee E EA ieee ates 22 20 Updating Type Definitions eseeseeesssseesesresrsrreresrererrsseeresrsrestesesresrerrsreetsseee 22 21 Searching for Type Definitions eee ceseeteceeceseeeeeeeeeeeceaeeeeeenessaeeneenaes 22 22 Cluster Type Definitions 0 eee ee ceeseesseseecsecseeseceseaecsceseseeeeseeeeseaeseaeenes 22 22 G Programming Reference Manual xvi National Instruments Corporation Table of Contents Chapter 23 Calling Code from Other Languages Executing Other Applications from within Your VIs cece ese csecseeeceeceneceeeeeees 23 1 Using the Call Library Function ieee cee ceseeseceeceseeeeceseeeeeeeeeeeseaeeeeseneeaes 23 2 Using Code Interface Nodes eee eeceseeseceeceseeseceseesecesceeseneesaseneesaecaeenaeraes 23 2 Call Library Funct oseere couche oko iee es e ae eea EE E ened dus Eea EE EEIE E Sra E R EY 23 3 Calling Conventions Windows ssssesesssseseesesssseeesessresrtssesstressesstesressrssresses 23 4 Parameter Vi Sts sce rasieren onde E co bow a a A bute ewcbevansiecebees Sess 23 5 Calling Functions that Expect Other Data Types cece ee ceeeseeeeeeeeeeeene 23 7 LabWindows CVI Function Panel Converter ceceeeseesceesecessecenceceeeesceeeneesaeeeeeeeeneees 23 7 Conver
35. The Save with Options dialog box makes it simple for you to save an entire hierarchy of VIs for distribution You can use this dialog box to selectively save an entire hierarchy without the VIs in vi lib and save all external subroutines that are referenced by VIs in your National Instruments Corporation 25 3 G Programming Reference Manual Chapter 25 Managing Your Applications hierarchy The Save with Options dialog box is shown in the following illustration Save with Options x Save Options for Untitled 1 ro te Changed Vs Selected Options o current location s no prompts Ly OCR Development pn Distribution o al Application E i gt Distribution C Remove diagram s Custom Save o 4 Ba Save Cancel By selecting from the options on the left of the Save with Options dialog box you can select from a set of predefined save options As you select options the area at the right shows the behavior of your current selection You can customize the behavior by selecting specific options from the right section of the dialog box G Programming Reference Manual Changed VIs Saves any changes to the front most VI and its subVIs This option is useful as a quick way to save changes Development Distribution Saves all non vi lib VIs controls and external subroutines to a single location either a directory or library This option is an easy way to save a hierarchy that is to be transported to another G
36. The media on which you receive National Instruments software are warranted not to fail to execute programming instructions due to defects in materials and workmanship for a period of 90 days from date of shipment as evidenced by receipts or other documentation National Instruments will at its option repair or replace software media that do not execute programming instructions if National Instruments receives notice of such defects during the warranty period National Instruments does not warrant that the operation of the software shall be uninterrupted or error free A Return Material Authorization RMA number must be obtained from the factory and clearly marked on the outside of the package before any equipment will be accepted for warranty work National Instruments will pay the shipping costs of returning to the owner parts which are covered by warranty National Instruments believes that the information in this manual is accurate The document has been carefully reviewed for technical accuracy In the event that technical or typographical errors exist National Instruments reserves the right to make changes to subsequent editions of this document without prior notice to holders of this edition The reader should consult National Instruments if errors are suspected In no event shall National Instruments be liable for any damages arising out of or related to this document or the information contained in it EXCEPT AS SPECIFIED HEREIN NATIONAL I
37. To minimize memory usage you should use consistent data types wherever possible Doing this produces fewer copies of data because of promotion of data in size Using consistent data types also makes the compiler more flexible in determining when data buffers can be reused In some applications you might consider using smaller data types For example you might consider using four byte single precision numbers instead of eight byte double precision numbers However you should carefully consider which data types are expected by subVIs you can call because you want to avoid unnecessary conversions G Programming Reference Manual 26 22 National Instruments Corporation Chapter 26 Performance Issues How to Generate Data of the Right Type Refer to the following example in which an array of 1 000 random values has been created and added to a scalar The coercion dot at the Add function occurs because the random data is double precision while the scalar is single precision The scalar is promoted to a double precision before the addition The resulting data is then passed to the indicator This diagram uses up 16 KB of memory 4K forthe 7 indicator K forthe DBL to Tsar SGL conversion The following illustration incorrectly attempts to correct this problem by converting the array of double precision random numbers to an array of single precision random numbers It uses the same amount of memory as the previous example
38. When a VI is marked as a subroutine the execution system minimizes the overhead to call a subVI There are a few trade offs however Subroutines cannot display front panel data G does not copy data from or to the front panel controls of subroutines they cannot contain timing or dialog box functions and they do not multitask with other VIs Subroutines are short frequently executed tasks and are generally most appropriate when used with VIs that do not require user interaction Unnecessary Computation in Loops Avoid putting calculations in loops if the calculation produces the same value for every iteration Instead move the calculation out of the loop and pass the result into the loop National Instruments Corporation 26 9 G Programming Reference Manual Chapter 26 Performance Issues For example examine the following diagram The result of the division is the same every time through the loop therefore you can increase performance by moving the division out of the loop as shown in the following illustration G Programming Reference Manual 26 10 National Instruments Corporation Chapter 26 Performance Issues If you know that the value of the global variable is not going to be changed by another concurrent diagram or VI during this loop this diagram wastes time by reading from the global variable and writing to the global every time through the loop If you do not need the global variable to be read from or writ
39. You can change the custom settings by selecting Configure after you select the custom option See the Creating Custom Print Settings section in this chapter for information on this dialog box Choosing Layout Options The Print Documentation dialog box contains several page layout options that control scaling page breaks and headers for the printout These are described as follows Scale Front Panel to Fit and Scale Block Diagram to Fit These two options control whether the panel and diagram sections are scaled to fit These options cause G to scale the front panel and or block diagram down to no less than one fourth the original size to fit on the fewest number of pages possible Print Header Prints a header at the top of every page This header includes the page number the VI name and the last modification date of the VI Page Breaks Between Sections Inserts a page break between the following sections e Connector icon and description e Front panel e List of front panel control details e Block diagram e Block diagram details e VI hierarchy e List of subVIs Creating Custom Print Settings To bring up the Custom Print Settings dialog box select the Custom button in the Print Documentation dialog box After you select Custom the Configure button is activated Click on this button to see the dialog box shown in the following illustration G Programming Reference Manual 5 4 National Instruments Corporation
40. and the format to use in passing the array Use the Format option to select if you want to pass a pointer to the array data or pass a pointer to a G array which includes a four byte value for each dimension followed by the data If you select Array Data Pointer you probably need to pass the array dimension as separate parameter s In Windows 3 1 the Call Library Node uses only the array data pointer format for arrays Additionally in Windows 3 1 you can indicate that the data should be passed using a Huge pointer You can use a Huge pointer if you need to pass more than 64 K You should only turn this option on if the DLL you are calling expects a Huge pointer of data If you try to pass a Huge pointer to a function that expects a normal pointer the application might crash If the library function that you are calling is written specifically for G you should use the G array format because it explicitly includes the size information For most conventional libraries however use the array data pointer and pass the size of the array as a separate parameter s G Programming Reference Manual 23 6 National Instruments Corporation Chapter 23 Calling Code from Other Languages Caution Do not attempt to resize an array with system functions such as realloc Doing so might cause your system to crash In Windows 3 1 you cannot use the String Handle format e Strings You can specify the string format for strings The options for
41. column For example say you have an array of 3 rows and 4 columns with values as shown in the following figure Rows and columns are zero based meaning that the first column is column 0 the second column is column 1 and so forth Changing the index display to row 1 column 2 displays a value of 6 as shown in the following illustration If you try to display something out of range the value display is grayed out to indicate there is no value currently defined for that value For example if you tried to display an element in row 10 of the array shown previously the display would be grayed out as shown in the following illustration gm F Displaying Arrays in Single Element or Tabular Form Array Resizing toal A new array appears in single element form The array displays the 00 value of a single element the one referenced by the index display You also can display the array as a table of elements by resizing the array shell from any of the four corners surrounding the element The array Resizing tool is slightly different from the usual Resizing tool when it National Instruments Corporation 14 9 G Programming Reference Manual Chapter 14 Array and Cluster Controls and Indicators Usual Resizing symbol is over the array shell resizing handles and the cursor changes to the usual symbol when you begin to resize An example is shown in the following illustration T
42. front panel control belonging to a terminal the label local variables and Attribute Nodes Local variables and Attribute Nodes referring to original controls are copied and switched so they refer to the copied control To copy and paste within a VI or between VIs select the object with the Positioning tool and choose Edit Cut or Edit Copy Then click on the area in which you want to place the duplicate and choose Edit Paste You can duplicate several objects at the same time by dragging a selection marquee around the objects before duplicating them You also can copy text or pictures from other applications and paste them into your front panel or block diagram G Programming Reference Manual 2 12 National Instruments Corporation Chapter 2 Building Vis To clone an object click the Positioning tool on it while pressing the lt Ctrl gt Windows lt opt ion gt Macintosh lt met a gt Sun or lt Alt gt HP UX key and drag the copy to its new location In UNIX you also can clone objects by clicking on and dragging the middle mouse button without modifier keys When you clone or copy objects G labels the copies with the same name as the original object with the word copy appended or copy 1 copy 2 etc for copies of copies On Windows and Macintosh you can use Drag and Drop capabilities to copy objects between VIs or from other applications To drag and drop an object select it with the Positioning tool and drag it
43. iz Note You must make sure that the label you choose for your local variable is associated with a front panel object If your local variable is not associated with a front panel object it will not work LOCAL local variable icon local variable node The easiest way to create a local variable is to pop up on the front panel control or terminal and select Create Local A local is created automatically on the block diagram Another way to create a local is to select the local variable from Functions Structures shown below Local Variable If there are no controls on the front panel of your VI a node that looks similar to a global variable appears If you already have placed controls on the front panel the local variable node appears with the name of one of your controls showing You can pop up on the node or click on it with the Operating tool to select the control you want to read or set from a list of the top level front panel controls as shown in the following illustration You also can determine whether you want to write to or read from the control by selecting either the Change to Write Local or the Change to Read Local options G Programming Reference Manual 21 4 National Instruments Corporation Chapter 21 Global and Local Variables Change To Read Local Select Item Show Description Replace Haiink Fg suiii Open Front Panel The following is an illustration showing how you can have multiple
44. lt gt lt amp amp Il lt unaryoperator gt lt arglist gt lt aexpr gt lt arglist gt lt const gt pi lt number gt G Programming Reference Manual 19 8 National Instruments Corporation Chapter 19 Formula Nodes The precedence of operators is as follows from lowest to highest assignment oa conditional logical or amp amp logical and l inequality equality lt gt lt gt other relational less than greater than less than or equal greater than or equal addition subtraction Key multiplication division unary positive negative logical not x exponentiation Exponentiation and the assignment operator are right associative groups right to left All other binary operators are left associative The numeric value of TRUE is and FALSE is 0 for output The logical value of 0 is FALSE and any nonzero number is TRUE The logical value of the conditional expression lt lexpr gt lt texpr gt lt fexpr gt is lt texpr gt if the logical value of lt lexpr gt is TRUE and lt fexpr gt otherwise Formula Node Errors Table 19 2 lists errors detected by the Formula Node Table 19 2 Formula Node Errors Error Message Error Message Meaning syntax error Misused operator and so on bad token Unrecognized character National Instruments Corporation 19 9 G Programming Reference Manual Chapter 19 Formula N
45. lt command gt Macintosh or lt meta gt Sun key The options in this ring are shown in the following illustration National Instruments Corporation 8 7 G Programming Reference Manual Chapter 8 Introduction to Front Panel Objects A list of the current keyboard associations labeled Current Assignments shown in the preceding illustration is located at the top right of the Key Navigation dialog box None Return gt Escape Home End gt lt Page Up lt Page Down Clear gt Panel Order Option Controls and indicators on a front panel have a logical order called panel order that is unrelated to their position on the front panel The first control or indicator you create on the front panel is element 0 the second is 1 and so on If you delete a control or indicator the panel order adjusts automatically You can change the panel order by selecting Edit Panel Order The appearance of the front panel G Programming Reference Manual 8 8 National Instruments Corporation Chapter 8 Introduction to Front Panel Objects changes because it is now in panel order edit mode as shown in the following illustration Click to set tol The white boxes on the controls and indicators show their current places in the panel order Black boxes show the new place in the panel order of the control or indicator Clicking on an element with the panel order cursor sets the position of the element in the pane
46. mantissa 0 National Instruments Corporation A 1 G Programming Reference Manual Appendix A S jio exp ojs Data Storage Formats 68K Macintosh Extended precision floating point numbers have 96 bit format MC68881 MC68882 extended precision format a5 80 64 a BE exp O15 zero 0 63 mantissa 0 Power Macintosh Extended precision floating point numbers are stored as two double precision floating point numbers combined that is the double double format that Apple has For more details see Inside Macintosh PowerPC Numerics mantissa shio exp O 51 mantissa tail Sun Extended precision floating point numbers have 128 bit format 127 112 o i4 exp O 7 111 mantissa D HP UX Extended precision floating point numbers are stored the same as double precision floating point numbers as shown in the next illustration Double Double precision floating point numbers have 64 bit IEEE double precision format format default J2 0 10 esp 0 51 mantissa 0 aE Single Single precision floating point numbers have 32 bit IEEE single precision format z1 2S o 22 mantissa o G Programming Reference Manual A 2 National Instruments Corporation Arrays Appendix A Data Storage Formats Long Integer Long integer numbers have 32 bit format signed or unsigned 31 E Word Integer Word integer numbers have 16 bit format signed or unsigned 13 E Byte Integer Byte integer numbers have 8
47. priority or change the calling VI to something other than subroutine priority You cannot run a VI if one of its subVIs already is running as a subVI of another VI subVI name subVI is in either panel order or cluster order mode You cannot run a VI if you ar changing the panel or cluster order of one of its subVIs subVI name subVI is in You cannot run a VI if one of its subVIs is in interactive retrieval mode interactive retrieval mode subVI name subVI is missing G was not able to find the subVI when it loaded the calling VI perhaps because you changed the name replace the bad subVI with a good one or open the missing subVI if you can find it subVI name subVI is not The subVI is broken Open it and repair its errors executable Terminal The associated array or cluster on the front panel has no elements its type is undefined You must place a control or indicator in the array or cluster Type Definition can t find valid type definition G was not able to find the type definition VI when it loaded the calling VI perhaps because you changed the name Open the missing type definition VIif you can find it pop up on the bad control and disconnect it from the type definition or replace it with a good control National Instruments Corporation 4 13 G Programming Reference Manual Chapter 4 Executing and Debugging VIs and SubVIs Table 4 1 Error Messages Continued
48. where each row is the results of a given test This result is shown in the following illustration descriptions National Instruments Corporation 26 31 G Programming Reference Manual Chapter 26 Performance Issues Given this data structure you can replace an array element directly using the Replace Array Element function as shown in the following illustration Case Study 2 Global Table of Mixed Data Types Here is another application in which you want to maintain a table of information In this application you decide you want the data to be globally accessible This table might contain settings for an instrument including gain lower and upper voltage limits and a name used to refer to the channel To make the data accessible throughout your application you might consider creating a set of subVIs to access the data in the table such as the following subVIs the Change Channel Info VI and the Remove Channel Info VI channel name gain lower limit upper limit Change Channel Info vi Remove channel name Channel Remove Channel vi The following section presents three different implementations for these VIs G Programming Reference Manual 26 32 National Instruments Corporation Chapter 26 Performance Issues Obvious Implementation With this set of functions there are several data structures you could consider for the underlying table First you might use a global variable containing an a
49. 0 followed by frame 1 then frame 2 until the last frame executes Only when the last frame completes does data leave the structure Within each frame as in the rest of the block diagram data dependency determines the execution order of nodes You use the Sequence Structure to control the order of execution of nodes that are not data dependent A node that receives its data directly or indirectly from another node has a data dependency on the other node and always executes after the other node completes You do not need to use the Sequence Structure when data dependency exists or when the execution order is unimportant This situation occurs often when you want to determine how long a function takes The Tick Count VI returns the start and end time in milliseconds The time is not needed to perform the function so there is no data dependency between time measurement and the function As shown in the following illustration the Tick Count VI to the left of the sequence structure executes before the sequence structure Then the function executes in frame 0 and the time elapsed calculation is done in frame 1 The sequence structure enforces the proper execution order G Programming Reference Manual 18 16 National Instruments Corporation Chapter 18 Structures start time Number of Iterations Output tunnels of Sequence Structures can have only one data source unlike Case Structures The output can emit from 4any frame but keep
50. 0 follows the backslash so G interprets B as hex OB Any time a backslash is not followed by a valid hex character G does not recognize the backslash character You can enter some nondisplayable characters from the keyboard such as a carriage return into a string control whether or not you select P Codes Display However if you enable the backslash mode when the display window contains text G redraws the display to show the backslash representation of any nondisplayable characters as well as the character itself Suppose the mode is disabled and you enter the following string left right 3F G Programming Reference Manual 11 4 National Instruments Corporation Chapter 11 String Controls and Indicators When you enable the mode the following string appears because the carriage return after 1e ft and the backslash characters following it are shown in backslash form as n left n right 3F Suppose now that you select Codes Display and you enter the following string left right 3F When you disable the mode the following string appears because G originally interpreted r as a carriage return and now prints one 3F is the special representation of the question mark and prints this way left ight Now if you select VP Codes Display again the following string appears left n right Indicators behave in the same way In these examples the data in the string does not change from one mode
51. 10 4 toggle switch simulation 10 2 toggling between TRUE and FALSE states 10 2 Boolean data storage formats A 1 border printing around panel 5 8 Bottom Edges alignment 2 12 Bounds Attribute Read Only 20 10 branch of wires 17 6 Breakpoint tool 2 5 4 26 breakpoints placing 4 26 to 4 29 Breakpoint tool 4 26 Clear Breakpoint cursor 4 26 display of breakpoints table 4 27 example 4 28 to 4 29 setting breakpoint 4 27 Bridge VIEW switching to Basic G palette note 2 1 Bring into View option 15 34 Broken Run button 4 10 17 11 broken VIs common reasons for broken VIs 4 11 correcting broken VI range errors 4 14 to 4 15 error messages table 4 11 to 4 14 fixing 4 10 to to 4 11 locating errors 4 10 Build Array function 16 10 building front panel 8 1 to 8 10 control and indicator options 8 2 to 8 4 Controls palette 8 1 to 8 2 customizing dialog box controls 8 9 to 8 10 imported graphics for customizing controls 8 10 to 8 11 Key Navigation option for controls 8 5 to 8 8 Panel Order option 8 8 to 8 9 replacing controls 8 4 to 8 5 National Instruments Corporation Index building subVIs 3 1 to 3 14 See also Hierarchy window creating from VI selections 3 10 to 3 14 Find pop up menu Attribute Nodes 3 29 global and local variables 3 29 avoiding cycles 3 12 to 3 13 Attribute Node in Case Structure 3 13 Attribute Nodes within loops 3 12 detection by G 3 12 front panel terminal in
52. 14 to 7 15 front panel preferences 7 9 to 7 11 history preferences 7 17 to 7 20 miscellaneous preferences 7 22 to 7 23 path preferences 7 2 to 7 6 performance and disk preferences 7 6 to 7 9 printing preferences 7 16 to 7 17 time and date preferences 7 21 storing preferences 7 23 to 7 25 Get Info option 3 21 Global Variable palette 21 1 global variables creating 21 1 to 21 2 definition 21 1 example 21 2 Find pop up menu 3 29 including in Hierarchy window 3 18 3 19 memory considerations 26 21 memory usage 26 21 placing in VIs 21 3 purpose and use 21 1 to 21 3 selecting 21 2 to 21 3 Globals option Select Objects menu 3 25 1 33 G Programming Reference Manual Index Goto Cursor option 15 35 graph cursors 15 30 to 15 36 array type behavior 15 32 components 15 32 controlling appearance of 15 33 to 15 34 cross hairs 15 33 to 15 34 cursor palette illustrations 15 31 deleting 15 33 lock button 15 35 moving 15 33 point style 15 34 purpose and use 15 30 reading programmatically example 20 14 to 20 15 visible name 15 35 graph indicators creating multiplot graph 15 5 to 15 11 waveform graph data types 15 5 to 15 9 XY graph data types 15 9 to 15 11 definition 15 1 examples located in examples 15 1 graph cursors 15 30 to 15 36 graph options 15 11 to 15 22 Autoscale 15 17 Formatting 15 15 to 15 17 graph pop up menu 15 11 to 15 12 illustration 15 12 legend options 15 19 to 15 22
53. 16 Wiring underneath Objects eee ee cee eee cseecseeeeseceeeeeeeeeeeeeseeaeeaes 17 17 Chapter 18 Structures For Loop and While Loop Structures ccccececcsesesseceescsscseseessscsscesssesecsessseeseeesaees 18 3 For LOOp a erreper eee E E Ee ae Ee E E sae eee tees dees 18 3 While Looper et nina E ea eae ee SN 18 4 Placing Objects inside Structures ccc esesseeescsecseeeseecsecssessssessesesssessesees 18 4 Placing and Sizing Structures on the Block Diagram eee eee eeeeeeeees 18 5 Placing Terminals inside LOOPS cccsscseseseseeeeesesseseessesecseceeessesesseseseeeses 18 6 Auto Indexing ii sacs a ee eet ie 18 7 Auto Indexing for Setting the For Loop Count eee 18 8 Auto Indexing with While Loops 0 eee seceseeseceseeeeceseeeeeeeeeeeees 18 9 Executing a For Loop Zero Times 0 0 0 cccccecssseseeesesesseseessesscseseeessesesseseseesses 18 9 Shift REGisters e eeeh eek ies Ree ne ane el se ees 18 10 G Programming Reference Manual xiv National Instruments Corporation Table of Contents Case and Sequence Structures eee ceeceeceseeseceeceseceeceeeeeeeeseeesecaeecaecsaesaecneeeseenseeseees 18 13 Case Structures si sssecicastescsssceshsscssetescdesedea csscsssdesassipsopeossesdavee ssveschvesi enscspeseeted 18 14 SEQUENCE StrUctUreS rinie oore eie Eet aere EE eE TEE KE EE S See e 18 16 Editing Case and Sequence Structures esseseeeseseesseeereeeereserresreseerrsreerrrrereees 18 18 Moving between Su
54. 18 25 to 18 26 Serial Port VIs 5 1 setting up VIs See SubVI Node Setup dialog box VI Setup dialog box shift registers 18 10 to 18 13 adding or removing terminals 18 11 to 18 12 definition 18 4 18 10 initializing 18 10 to 18 11 left and right terminals 18 10 lt Shift gt key positioning objects 2 9 sizing multiple rows or columns 11 7 G Programming Reference Manual Index lt Shift gt clicking executing Show All SubVIs action 3 21 selecting multiple nodes 3 22 table rows and columns 11 7 to 11 9 selecting and deselecting objects 2 7 using with selection rectangle 2 8 lt Shift Enter gt key advancing through text scale labels 9 19 creating text scale labels 9 18 finding previous matching node 3 23 lt Shift Return gt key advancing through text scale labels 9 19 creating text scale labels 9 18 finding previous matching node 3 23 Show Abort Button option 4 4 Show All Callers option 3 21 Show All SubVIs option 3 21 Show All VIs option 3 18 Show Case option 18 18 Show Connector command 1 6 3 5 Show Diagram command 1 3 2 4 Show Digital Display option ring controls 13 8 slide controls and indicators 9 14 Show Error List command 4 10 Show Front Panel When Called option SubVI Node Setup dialog box 6 6 VI Setup dialog box 6 2 Show Front Panel When Loaded option 6 2 Show Help command 1 7 Show History command 25 6 Show Immediate SubVIs option 3 20 3 21 Show Last Element option 14 13 Sho
55. 22 file I O functions for retrieving logged data 4 9 file management arranging files in VI libraries 25 1 to 25 2 backing up files 25 2 File menu Apply Changes 22 3 Edit VI Library 2 30 Page Setup 5 2 Printer Setup 5 2 Revert 2 28 3 11 22 11 Save 2 28 22 20 Save a Copy As 2 28 G Programming Reference Manual Save As 2 28 22 4 Save With Options 2 28 Fill Baseline option 15 21 fill bucket tool Icon Editor 3 3 Fill Options option 9 20 Fill to Value Above option 9 20 Fill to Value Below option 9 20 filled and multivalued slides 9 20 filled rectangle tool Icon Editor 3 4 Find command Project menu 3 23 Find Control option 20 6 Find dialog box 3 24 to 3 29 finding text 3 26 to 3 27 More Options button 3 27 narrowing search scope 3 27 to 3 28 All VIs in Memory option 3 27 Name of a VIs option 3 28 Selected VIs option 3 28 next and previous search items 3 29 Objects button 3 24 Search Results window 3 28 to 3 29 Clear option 3 28 Find option 3 28 Go To option 3 28 Stop option 3 29 search string options Match Case 3 26 Match Whole Word 3 26 Regular Expression 3 26 Select Objects menu Functions option 3 25 Globals option 3 25 illustration 3 25 Objects in vi 1ib option 3 25 Others option 3 25 Type Defs option 3 25 VIs by Name option 3 25 VIs option 3 25 Text button 3 26 National Instruments Corporation Index text search options font window 2 17 Search
56. 25 1 to 25 9 See also calling code from other languages backing up files 25 2 distributing VIs 25 2 to 25 4 keeping master copy 25 5 multiple developers 25 5 to 25 9 storing VIs in libraries 25 1 to 25 2 using Save with Options 25 3 to 25 4 Application Distribution 25 4 Changed VIs 25 4 Custom Save 25 4 Development Distribution 25 4 VI History window 25 5 to 25 9 example 25 6 printing history information 25 9 recording comments note 25 6 related VI Setup and Preferences dialog options 25 9 resetting history information 25 8 revision numbers 25 7 to 25 8 Apply Changes option 22 3 arbitrary scale markers See scale markers Array amp Cluster palette 14 1 14 5 Array Resizing tool 14 9 array shell creating array controls 14 5 to 14 7 element display 14 5 index display 14 5 placing on front panel 14 5 undefined 14 12 Array To Cluster function 14 28 to 14 29 arrays and array controls 14 1 to 14 11 Array Resizing tool 14 9 creating 14 5 to 14 11 array dimensions 14 7 to 14 8 combining array shell with valid element 14 5 defining array type 14 6 to 14 7 index display pop up menu 14 7 G Programming Reference Manual l 16 data storage formats A 3 to A 5 data type 23 6 to 23 7 default size and values 14 11 to 14 13 definition 14 1 description 14 1 to 14 4 displaying in single element or tabular form 14 9 to 14 11 empty arrays 14 12 finding array size 14 13 flattened data A 13 to A 14 G
57. 4 5 6 Column by 4 Row Array of 24 Elements A simple example is a chess board There are eight columns and eight rows for a total of 64 positions each of which can be empty or have one chess piece You can represent a chess board as a two dimensional array of strings Each string has the name of the piece occupying the corresponding location on the board or it is an empty string if the location was empty Other familiar examples include calendars train schedule tables and even television pictures which can be represented as two dimensional arrays of numbers giving the light intensity at each point Familiar to computer users are spreadsheet programs which have rows and columns of numbers formulas and text All of the one dimensional array examples can be generalized to two dimensions A collection of waveforms represented as a two dimensional array of numbers is shown in the following National Instruments Corporation 14 3 G Programming Reference Manual Chapter 14 Array and Cluster Controls and Indicators illustration The row index selects the waveform and the column index selects the point on the waveform point index waveform 0 0 4 0 9 1 4 0 8 0 1 0 7 0 3 0 3 0 2 volts indices 1 0 5 0 6 0 4 10 2 0 8 1 61 1 4 0 9 1 1 2 1 6 1 4 0 7 0 5 0 5 0 6 0 2 0 3 0 5 Multiple Waveforms in a 2D Array of Numbers Arrays can have an arbitrary number of dimensions but one index per dimension is
58. 5 6 Select Item menu 21 2 Select Objects menu Find dialog box Functions 3 25 Globals 3 25 illustration 3 25 Objects in vi lib 3 25 Others 3 25 Type Defs 3 25 VIs 3 25 VIs by Name 3 25 select tool Icon Editor 3 4 selecting objects 2 7 to 2 8 multiple selection with selection rectangle 2 7 to 2 8 lt Shift gt clicking 2 7 2 8 Selection Mode option 13 4 to 13 5 Multiple Selection listbox 13 5 Single Selection listbox 13 5 selection rectangle for multiple selections 2 7 to 2 8 selector terminals 18 14 separator character differences when porting VIs between platforms 27 2 National Instruments Corporation Index sequence locals adding 18 17 assigning more than one value to 18 22 Sequence Structures adding subdiagrams 18 19 to 18 20 deleting subdiagrams 18 20 to 18 21 editing 18 18 example in examples 1l1b vi 18 16 icon for 18 2 18 13 moving between subdiagrams 18 18 to 18 19 overview 18 13 to 18 14 purpose and use 16 11 18 16 to 18 18 reordering subdiagrams 18 21 sequence locals 18 17 to 18 18 subdiagram display window 18 13 wiring problems 18 22 to 18 26 assigning more than one value to a sequence local 18 22 failing to wire a tunnel in all cases of a Case Structure 18 22 overlapping tunnels 18 23 removing structures without deleting items in a structure 18 26 wiring from multiple frames of Sequence Structure 18 24 to 18 25 wiring underneath rather than through a structure
59. 9 to 7 11 Blink speed 7 10 End text entry with Return key same as Enter key 7 10 illustration 7 9 Open the control editor with double click 7 9 Override system default function key settings 7 10 Support numeric keypad on Sun keyboards 7 10 Use localized decimal point 7 10 Use smooth updates during drawing 7 10 Use transparent name labels 7 10 History Preferences 7 17 to 7 20 Add an entry every time VI is saved 7 18 illustration 7 18 Login automatically with the system user name 7 20 Prompt for comment when VI is closed 7 19 National Instruments Corporation Prompt for comment when VI is saved 7 18 to 7 19 Record comments generated by the editor 7 19 Show revision number in titlebar 7 19 Show the login prompt at startup time 7 19 to 7 20 Miscellaneous Preferences dialog box 7 22 to 7 23 Allow drop through clicks 7 23 illustration 7 22 Open VIs in run mode 7 22 Show tips strips 7 22 Use hot menus 7 23 Use native file dialogs 7 22 Path Preferences dialog box 7 2 to 7 6 format of pathnames note 7 3 illustration 7 2 library temporary and default directories 7 3 to 7 4 removing paths with Remove button 7 6 VI search path 7 5 to 7 6 Performance and Disk Preferences dialog box 7 6 to 7 9 Check available disk space during launch 7 9 Compact memory during execution 7 8 Cooperation level 7 9 Deallocate memory as soon as possible 7 7 illustration 7 7 Perf
60. B 13 iteration terminal 18 3 J junction of wires 17 6 Justify option Font ring 2 17 National Instruments Corporation K Key Focus Attribute 20 8 Key Navigation option 8 5 to 8 8 current keyboard associations 8 8 disabled for indicators note 8 5 lt Enter gt and lt Return gt key associations 8 6 Key Navigation dialog box 8 7 Keyboard Mode option Case Insensitive suboption 13 6 Case Sensitive suboption 13 6 System Default suboption 13 6 L Label command 2 3 2 13 2 16 labeling objects 2 14 to 2 22 free labels 2 14 to 2 16 text characteristics 2 16 to 2 22 Labeling tool 2 5 labels copying text 2 15 default labels for structures and functions 2 15 differences when porting VIs between platforms 27 3 displaying function labels 16 9 hidden labels 2 16 free labels 2 14 to 2 16 front panel 2 3 hiding 2 13 numeric scales 9 18 to 9 19 min and max labels 9 18 to 9 19 overlapping 2 15 27 3 owned labels controls or indicators 2 15 definition 2 14 leaving blank 2 15 resizing 2 23 showing 2 3 2 16 subVIs on block diagram note 2 16 transparent 7 10 National Instruments Corporation Index LabWindows CVI Function Panel converter 23 7 to 23 13 Conversion Options dialog box Add Instrument Error I O Checking 23 11 Assign Instrument Driver Icon Based on Name 23 12 Assume 15 bit DLL 23 11 Capitalize and Remove Underscores in Names 23 12 Convert All Contr
61. Black amp White but you can click on one of the other color options to switch You can copy from a color icon to a black and white icon and from black and white to color as well by using the Copy from options at the right of the Icon Editor Note Itis best to create a black and white icon If you design a color icon it does not show up if you add it to the Functions palette Also you cannot print it out and it does not show up ona black and white monitor G uses the blank black and white icon in these cases The tool icons to the left of the editing area perform the following functions pencil Draws and erases pixel by pixel Use the lt Shift gt key to restrict drawing to horizontal and vertical lines line Draws straight lines Use the lt Shift gt key to restrict drawing to horizontal vertical and diagonal lines Z dropper Selects a color to be the foreground color from an element in the icon Use the lt Shift gt key to select the background color with the dropper F fill bucket Fills an outlined area with the foreground color rectangle Draws a rectangular border in the foreground color Double click on this tool to frame the icon in the foreground color Use the lt Shift gt key to constrain the rectangle to be a square 0 el National Instruments Corporation 3 3 G Programming Reference Manual Chapter 3 Building SubVis filled rectangle Draws a rectangle bordered with the foreground col
62. Chapter 26 Performance Issues N CI Ez If you want to add a value to the array with every iteration of the loop you can see the best performance by using auto indexing on the edge of a loop With For Loops the VI can predetermine the size of the array based on the value wired to N and resize the buffer only once With While Loops auto indexing cannot be quite as efficient because the end size of the array is not known However While Loop auto indexing avoids resizing the output array every iteration by increasing the output array size in large increments When the loop is finished the output array is resized to the correct size The performance National Instruments Corporation 26 25 G Programming Reference Manual Chapter 26 Performance Issues of While Loop auto indexing is nearly identical to For Loop auto indexing Auto indexing assumes that you are going to add a value to the resulting array with each iteration of the loop If you need to conditionally add values to an array but you can determine an upper limit on the array size you might consider preallocating the array and then using Replace Array Element to fill up the array When you are finished filling up the array values you can resize the array to the correct size The array is created only once and Replace Array Element can reuse the input buffer for the output buffer The performance for this is very similar to the performance of loops usin
63. Chapter 5 Printing Vis Custom Print Settings Icon and Description Block Diagram EJ WI Connector and Icon Hidden Frames Ps Wl Description Repeat Higher Level Frames 8 Front Panel E ront Pane EJ Surround Panel With Border I Hierarchy List of Sublls VI History Layout Options El Scale Front Panel to Fit kal Print Page Header name date page EJ Scale Block Diagram to Fit Page Breaks between Sections is Print Section Headers es r Save Text Info Cancel This dialog box displays the categories of items that you can print These categories are listed in the order that they appear on the printout In addition the page layout options in this dialog box control scaling page breaks and headers for the printout The icon for each of the custom print setting options is shown to the left of the description Icon and Description VI Connector and Icon Prints a picture of the VI icon along with its inputs and outputs IE i He VI Description Prints the VI description Front Panel Prints the front panel al Controls Prints a list of the names of the controls and indicators When an array cluster or refnum is encountered the subcontrols are me National Instruments Corporation 5 5 G Programming Reference Manual Chapter 5 Printing VIs printed You can select the follow
64. Controls syscssee EEES sts sh eaateacs bie hastened T 13 7 Adding Text Items to RingS oo ec eeesecseeesececeseeeceseeseceseeseseeeeeseaeeaeeeaeaee 13 8 Adding Picture Items to Rings 000 0 csese cee ceseeseceseeseceseeseeeeeeeeseaseneeeaeenee 13 9 Changing the Size and Text of Text amp Pict Rings eee ceeceeenecneeees 13 10 Enumerated Type Controls iisen ierre iene i srra cndesbescscvacveesvceesegvasbvse sete stots 13 10 Chapter 14 Array and Cluster Controls and Indicators AA S E laced e a A cose ta lone a EEA ae A E E N a TS ara aN 14 1 Creating Array Controls es isccsc c scihice scenesstecipedesosetipepesbeseseedesseateesateeacepessacesbeys 14 5 Array DIMmensSiOns esi Mots unck aa stuck ses Woes Aa E i 14 7 Array Index Displays icc sccscsecesscestoessatascesteescetsaescseiesasesiseedcsvessspescbvess 14 8 Displaying Arrays in Single Element or Tabular Form 0 0 14 9 Operating Array So keetis epe eer TER geese sees ch TE Ep TE EErEE EEE EET EE iSt 14 11 Default Sizes and Values of ATrrayS eseeeseessersersrerrsreerrrrererrsererese 14 11 Array Elements 5 225565 i052 seg sdedess duc soes asc eestin nEs persnr Eo Tipo ni EREE Se Sss 14 13 Finding the Size of ATrayS eseseeeeseeesseeersseesrsrssrrrssrerrsrerrsreererrereerese 14 13 Moving or Resizing Arrays ee eesseesessesrssressresrrsrreressesseererseereeeseesees 14 14 Selecting Array Cells manion ienr Aioni eaen eaa oere o 14 14 An Example of Selecting Arr
65. Corporation Chapter 26 Performance Issues e Do not use complicated hierarchical data types for example arrays of clusters containing large arrays or strings or clusters containing large arrays or strings You might end up using more memory and performance suffers See the section on Developing Efficient Data Structures later in this chapter for more details and suggestions for tactics in designing your data types Memory Issues in Front Panels When a front panel is open controls and indicators keep their own private copy of the data that they display The following illustration shows the increment function with the addition of front panel controls and indicators De When you run the VI the data of the front panel control is passed to the diagram The increment function reuses the input buffer The indicator then makes a copy of the data for display purposes Thus there are three copies of the buffer This data protection of the front panel control prevents the case in which you enter some data into a control run the associated VI and see the data change in the control as it is passed in place to subsequent nodes Likewise data is protected in the case of indicators so that they can reliably display the previous contents until they receive new data With subVIs you can use controls and indicators as inputs and outputs The execution system makes a copy of the control and indicator data of the subVI in the followi
66. Cut Copy Paste and Clear If you turn this override option on the function keys are not used for system purposes but are passed instead to G as standard function keys Use localized decimal point Uses the decimal separator for the system instead of the period For example in many countries the comma is used as a decimal point Turn this option on if you want G to pay attention to the way you have configured your system Turn it off if you want G to use periods in all cases for the decimal point Use smooth updates during drawing When G updates a control with smooth updates off it erases the contents of the control and draws the new value This can result in a noticeable flicker as the old value is erased and replaced Using smooth updates G draws data to an offscreen buffer and then copies that image to screen instead of erasing a section of the screen This avoids the flicker caused by erasing and drawing However it can slow performance and it requires more application memory because an offscreen drawing buffer has to be maintained Use transparent name labels Directs G to use labels that you can see through Sun Support numeric keypad on Sun keyboards Turns on support for the Sun keyboard including keypads arrow keys and the Help key Do not turn this option on if you are using a non Sun keyboard for example if you are using an X terminal or a PC running X software Blink speed Sets the blinking speed for front
67. For many editing operations such as moving copying and deleting you must select an object To select an object click on the mouse button r while the Positioning tool shown at the left is over the object When you have selected an object G surrounds it with a moving dashed Positioning outline called a marquee Tool Not selected Selected To select more than one object lt Shift gt click on each additional object You also can deselect a selected object by lt Shift gt clicking on it Another way to select one or more objects is to drag a selection rectangle around the object s as shown in the following illustration Multiple selection Multiple selection by lt Shift gt clicking with selection rectangle National Instruments Corporation 2 7 G Programming Reference Manual Chapter 2 Building Vis Click on an open area with the Positioning tool and drag diagonally until all the objects you want to select are within or are touched by the selection rectangle When you release the mouse button the selection rectangle disappears and a marquee surrounds each selected object Then you can move copy or delete the selected objects Some objects must be enclosed completely by the rectangle to be selected Others are selected when they are partially enclosed By holding down the lt Shift gt key while dragging the selection rectangle you can select additional objects or deselect an object enclosed by the rectangle Clic
68. Glossary artificial data dependency ASCII asynchronous execution ATE Attribute Node auto indexing autoscaling autosizing block diagram BNF Boolean controls and indicators G Programming Reference Manual Condition in a dataflow programming language in which the arrival of data rather than its value triggers execution of a node American Standard Code for Information Interchange Mode in which multiple processes share processor time For example one process executes while others wait for interrupts during device I O or while waiting for a clock tick Automatic test equipment Special block diagram nodes you can use to control the appearance and functionality of controls and indicators Capability of loop structures to disassemble and assemble arrays at their borders As an array enters a loop with auto indexing enabled the loop automatically disassembles it with scalars extracted from one dimensional arrays one dimensional arrays extracted from two dimensional arrays and so on Loops assemble data into arrays as they exit the loop according to the reverse of the same procedure Ability of scales to adjust to the range of plotted values On graph scales this feature determines maximum and minimum scale values as well Automatic resizing of labels to accommodate text that you enter Pictorial description or representation of a program or algorithm In G the block diagram which consists of executable
69. Loop that contains the current number of completed iterations G 8 National Instruments Corporation label Labeling tool LED legend marquee matrix MB menu bar mnemonic modular programming NaN nodes nondisplayable characters not a path not a refnum National Instruments Corporation Glossary Text object used to name or describe other objects or regions on the front panel or block diagram Tool used to create labels and enter text into text windows Light emitting diode Object owned by a chart or graph that display the names and plot styles of plots on that chart or graph A moving dashed border that surrounds selected objects Two dimensional array Megabytes of memory Horizontal bar that contains names of main menus A string associated with an integer value Programming that uses interchangeable computer routines Digital display value for a floating point representation of not a number typically the result of an undefined operation such as log 1 Execution elements of a block diagram consisting of functions structures and subVIs ASCII characters that cannot be displayed such as newline tab and so on A predefined value for the path control that means the path is invalid A predefined value that means the refnum is invalid G 9 G Programming Reference Manual Glossary numeric controls and indicators 0 object Object pop up menu tool one dimensiona
70. Loose Fit 15 17 Marker Spacing 15 13 to 15 14 panning and zooming options 15 17 to 15 19 scale options 15 12 to 15 17 intensity graph 15 29 to 15 30 data type 15 29 options 15 29 to 15 30 questions about B 1 to B 4 waveform and XY graphs 15 2 to 15 22 creating single plot graphs 15 2 to 15 4 illustration 15 2 G Programming Reference Manual waveform graph data types 15 2 to 15 3 XY graph data types 15 3 to 15 4 Graph palette 15 1 graph pop up menu 15 12 graphics importing See also pictures Boolean controls and indicators 10 6 controls 8 10 to 8 11 grayed out dividing line listbox controls 13 6 Grid Options 15 15 H handles flattened data A 13 headers printing Print Header option 5 4 5 8 Print Section Headers option 5 6 help information 1 7 to 1 9 attribute node help 1 9 block diagram help 1 7 to 1 9 creating your own help files 1 9 to 1 10 adding documentation 6 4 front panel help 1 7 locking 1 7 online reference 1 9 Help menu Lock Help command 1 7 Online Reference command 1 9 Show Help command 1 7 Simple Help command 1 7 Help Path box VI Setup dialog box 6 4 Help Tag box VI Setup dialog box 6 4 Help window Attribute Nodes 20 6 wiring connection information 17 5 lt Help gt key 1 7 hex characters backslash V code table 11 4 displaying strings as hex characters 11 5 Hex Display option 11 5 hidden labels displaying 2 16 Hide All SubVIs option Hierarchy Node P
71. Manual Glossary drag DUT E empty array EOF execution highlighting external routine F FFT file refnum flattened data For Loop Formula Node frame free label G Programming Reference Manual To drag the mouse cursor on the screen to select move copy or delete objects Device under test Array that has zero elements but has a defined data type For example an array that has a numeric control in its data display window but has no defined values for any element is an empty numeric array End of File Character offset of the end of file relative to the beginning of the file that is the EOF is the size of the file Feature that animates VI execution to illustrate the data flow in the VI See shared external routine Fast Fourier transform An identifier that G associates with a file when you open it You use the file refnum to indicate that you want a function or VI to perform an operation on the open file Data of any type that has been converted to a string usually for writing it to a file Iterative loop structure that executes its subdiagram a set number of times Equivalent to conventional code For i 0 to n 1 do Node that executes formulas that you enter as text Especially useful for lengthy formulas that would be cumbersome to build in block diagram form Subdiagram of a Sequence Structure Label on the front panel or block diagram that does not belong to any othe
72. Menu Options The listbox pop up menu includes the options shown in the following illustration The options unique to listbox controls are described in this section Change to Indicator Find Terminal Show gt Data Operations gt Create gt Key Navigation Replace gt Selection Mode gt Keyboard Mode gt Disable Item tem Symbol d National Instruments Corporation 13 3 G Programming Reference Manual Chapter 13 List and Ring Controls and Indicators Show You use Show from the pop up menu shown in the following illustration to select which components of the listbox are visible You also can choose to show or hide the label the scrollbar and the symbols Change to Indicator Find Terminal S h ov gt Data Operations gt Scrollbar Create ag f Symbols Key Navigation Replace gt Selection Mode gt Keyboard Mode gt Disable Item tem Symbol gt If you select Show Symbols the listbox adds an extra column to the left side of the list for symbols An example of this is shown in the following illustration Initially no items have symbols You can add symbols using the Attribute Node lt Option 1 Option 2 O Option 3 Option 4 Option 5 Selection Mode You use Selection Mode from the pop up menu to indicate how many items you can select at once G Programming Reference Manual 13 4 National Instruments Corporation Chapter 13 List and Ring Controls and Indica
73. Objects Wires connect only those objects that you click on Dragging a terminal or icon on top of a wire makes it appear as if a connection exists when it does not as shown at the left of the illustration that follows 1 2 3 on the left Dragging a wire through an icon or terminal also appears to make a connection but the wire is actually behind the icon as shown at the right of the illustration 1 2 3 on the right Avoid these situations because they are confusing visually See the Understanding Warnings section in Chapter 4 Executing and Debugging VIs and SubVIs for more information on this problem National Instruments Corporation 17 17 G Programming Reference Manual Chapter Structures This chapter describes how to use the For Loop While Loop Case Structure and Sequence Structure These structures are in the Functions Structures palette as shown in the following illustration See general structs 11b for examples of how to use these structures Structures are nodes that supplement the flow of execution in a block diagram just as control structures do in a conventional programming National Instruments Corporation 18 1 G Programming Reference Manual Chapter 18 Structures language The icon for each G structure is a resizeable box with a distinctive border as shown in the following illustration Sequence Structures IN i For Loop Ej While Loop Case Structures S Boolean
74. Overlapping Tunnels Because G creates tunnels as you wire tunnels sometimes overlap Overlapping tunnels do not affect the execution of the diagram but they can make editing difficult Avoid creating overlapping tunnels If they occur drag one tunnel away to expose the other Look at the following example National Instruments Corporation 18 23 G Programming Reference Manual Chapter 18 Structures It is difficult to tell which tunnel is on top You can make mistakes if you try to wire to one of them while they overlap although you always remove the bad wires and try again If you need to wire from an object inside a structure to an object outside when one such wire already exists do not wire through the structure again as shown in the above illustration Instead begin the second wire at the tunnel In this example two overlapping tunnels do not cause a problem But if this was a Case Structure two overlapping bad tunnels might have appeared to be wired in each case You always can remove all the wires from a tunnel to make it vanish and then rewire correctly If your VI has tunnels that are completely overlapping a warning appears in the Error List window if you have selected Show Warnings See the Understanding Warnings section in Chapter 4 Executing and Debugging VIs and SubVIs for more information on these problems Wiring from Multiple Frames of a Sequence Structure This next illustration shows another variation
75. Required Recommended Optional In the Help window Required connections appear in bold Recommended connections are in plain text and Optional connections are in grayed out text Deleting Terminal Connections You can delete connections between terminals and their corresponding controls or indicators individually or all at once To delete a particular connection pop up on the terminal you want to disconnect on the National Instruments Corporation 3 9 G Programming Reference Manual Chapter 3 Building SubVis connector and choose Disconnect This Terminal from the pop up menu as shown in the following illustration UI Setup Edit Icon Show Icon Patterns Rotate 90 Degrees Flip Horizontal Flip Vertical Disconnect All Terminals Disconnect This Terminal This Connection Is The terminal turns white indicating that the selected connection no longer exists To delete all connections on the connector choose Disconnect All Terminals from the pop up menu anywhere on the connector G also deletes all existing connections automatically if you select a new pattern from the Patterns palette If you delete a control or indicator from the front panel it is disconnected from its connector terminal if one exists Confirming Terminal Connections To see which control or indicator is assigned to a particular terminal click on a control indicator or terminal with the Wiring tool when the connector pa
76. String amp Table wf wh woj 100 Key Navigation List amp Ring a CEs Array amp Cluster Be GRC Graph oo or ee Path E RefNum dd dhd gd da gd dwd dd dhd Decorations 4 ee ae Control ioe Or O z a eA Error Cluster VISA Transition gt J o Vertical Pointer Slide G Programming Reference Manual 8 4 National Instruments Corporation Chapter 8 Introduction to Front Panel Objects The next illustration shows the result speed settings 100 00 7 80 00 60 00 40 00 20 00 The new slide has the same height scale value name description and so on If you were to pop up and replace the slide with a string instead only the name description and data flow direction are preserved because a slide does not have much in common with a string Another way to replace a control that does not use the Replace pop up menu and does not preserve any characteristics of the old control involves copying the control to the Clipboard This method does keep the connections on the block diagram and VI connector Copy the new control to the Clipboard Then select the old control that you want to replace with the Positioning tool and select Edit Paste The old control is discarded and the new control is pasted in its place Key Navigation Option for Controls All front panel controls have a Key Navigation
77. Total Time 26 3 VI Time 26 3 viewing results 26 3 speeding up VIs 26 6 to 26 11 input output 26 6 to 26 7 parallel diagrams 26 8 to 26 9 screen display 26 7 subVI overhead 26 9 unnecessary computation in loops 26 9 to 26 11 Picture Item option 22 12 National Instruments Corporation Index pictures See also cosmetic parts customizing Boolean controls and indicators 8 10 to 8 11 controls 8 10 to 8 11 differences when porting VIs between platforms 27 4 to 27 5 dragging and dropping 2 8 to 2 9 ring controls adding 13 9 changing 13 10 Plot Color Attribute 20 10 to 20 11 Plot Info Plot Color option 20 10 plot sample definition 15 19 pop up menu 15 19 plots 15 1 Point Style option 15 20 points 14 19 15 4 polymorphic units 9 35 pop up menus Allow Run Time Pop Up Menu option 6 5 displaying hidden labels 2 16 illustration 2 6 using 2 6 pop up panels creating overview 6 1 to 6 2 SubVI Node Setup dialog box 6 6 VI Setup dialog box documentation options 6 3 to 6 4 execution options 6 2 to 6 3 window options 6 4 to 6 6 portability issues 27 1 to 27 5 ease of porting between platforms 27 2 nonportable VIs 27 1 overview 27 1 picture differences 27 4 to 27 5 G Programming Reference Manual Index questions about B 6 resolutions and font differences 27 2 to 27 4 labels 27 4 predefined fonts 27 2 to 27 3 separator character differences 27 2 Position Attribute 20 9 positioning
78. Unbundle By Name function over the Unbundle function is that it is not as closely tied to the data structure of the cluster The Bundle function always must have exactly the same number of terminals as it has elements If you add or remove an element from a cluster connected to an Unbundle function you end up with broken wires With the Unbundle By Name function you can add elements to and remove elements from the cluster without breaking the VI as long as the elements were not referenced on the diagram National Instruments Corporation 14 31 G Programming Reference Manual Chapter 14 Array and Cluster Controls and Indicators For example with the previous cluster you add a string for birthdate and the diagram still is correct This example is shown in the following illustration ht birthdate LT As with Bundle By Name the Unbundle By Name function is particularly useful in larger applications in conjunction with type definitions See the Bundle By Name Function section of this chapter and the Type Definitions section of Chapter 22 Custom Controls and Type Definitions for more information Cluster To Array Function The Cluster To Array function which you obtain from the Conversion Cluster To Array palette of the Functions palette converts the elements of a cluster into function a 1D array of those elements The cluster elements must all be the same type The array contains the same number of elements as the cluster
79. VI Setup to make a VI run when opened If you specify a library 11b to be opened when your application is launched it opens all VIs marked Auto Load Use File Edit VI Library to mark VIs with Auto Load Finally if you specify a library and no VIs are marked Auto Load a file dialog box prompts the user to select a VI within the specified 11b To tell LabVIEW or Bridge VIEW to launch a particular VI follow the instructions that follow for the relevant platform Windows Select the LabVIEW or Bridge VIEW icon select File Properties in Program Manager and change the pathname in Command Line to point towards your VI For example to make LabVIEW load test vi automatically set the Command Line to c labview labview exe test vi If test vi is inside a library called test 11b then c labview labview exe test 1llb test vi You may need to specify the full path to the VI Macintosh There is no way to have the LabVIEW application to launch a particular VI on the Macintosh automatically however you can launch a VI by double clicking on its icon in the Finder If you have multiple copies of LabVIEW installed on your machine the Finder determines which copy launches when you double click on the VI you have no control over which copy is launched For example the Finder may decide to launch the Run Time System if you have both the Run Time System and Full Development System installed If you are running System 7 you ca
80. VI library in the application the library is combined with a run time engine into a single file When this file is launched it automatically opens all top level VIs in the library If you do not embed a VI library the application can be used to open any VI when it is launched assuming the VI was saved with a development system for that platform If you enable the Open menu item you can use the application to open and run any VI in the file system regardless of whether the application has an embedded VI library By embedding a VI library you can create a completely stand alone application one that prevents the user or customer from accessing the source VIs even if the user has the development system If you plan to ship multiple VI suites to the same customer the single run time application with the Open menu item enabled proves more efficient than separate embedded applications This is true because each embedded application contains a copy of the run time code which is roughly 2 to 3 MB To create a run time application you need the Application Builder libraries which are sold separately If you are a LabVIEW user see the LabVIEW Release Notes included with the Application Builder software for details on how to build an application Note Because the BridgeVIEW execution system consists of several separate pieces the Application Builder does not work for building BridgeVIEW run time applications Save with Options Dialog Box
81. When you are in run mode these options are directly available when you pop up on an array The selection process is detailed in the following example An Example of Selecting Array Cells Begin by selecting Show Selection from the pop up menu Show Selection must be activated for your selected cells to be visibly marked A border surrounds selected cells You can select Add Element Gap from the pop up menu This separates the cells by a thin open space Although it is not necessary to add the element gap this open border improves the appearance of the array When you select cells this open space is filled by a thick border denoting the selected cells If you do not add the element gap the selection border appears over the selected cell edge G Programming Reference Manual 14 14 National Instruments Corporation You define the cells for selection with the array index The following Chapter 14 example uses a two dimensional array Set the array index for 1 1 Choose Start Selection from the pop up menu Set the array index to 3 3 Choose End Selection from the pop up menu The selected cells are surrounded by a blue border thick black on a monochrome system The selection includes the cells denoted by lower index numbers but not the cells denoted by the higher index numbers If you want to include National Instruments Corporation Change to Indicator Find Terminal Show Data Operations Create Key Naviga
82. You also can make multiple selections by dragging a rectangle over the objects you want to select e Pressing the lt Tab gt key toggles between the Positioning and the Scroll tool of the Tools palette Finding Hierarchy Node Mechanism A Find Hierarchy Node mechanism is available to search currently visible nodes in the Hierarchy window by name You can initiate the search by simply typing in the name of the node A small Search window appears displaying the text that has been typed The search takes place immediately and highlights a matching node by displaying a Tip strip of its name In the following illustration the Find Hierarchy Node mechanism has found the node named drawJoint vi drawJoint ui Hierarchy T draw Joint vi A search is performed as you type thus when no node matches the characters currently displayed in the Search window the system beeps and no more characters can be typed You then can use the lt Backspace gt or lt Delete gt key to delete one or more characters so that you can resume typing G Programming Reference Manual 3 22 National Instruments Corporation Chapter 3 Building SubVis The Search window disappears automatically if no keys are pressed for a certain amount of time You can press the lt Esc gt key to remove the Search window immediately When a match has been made on a node you can use the right or down arrow key or the lt Enter gt on Windows and Sun or the lt
83. a list of files use the Attribute Node Selecting Listbox Items There are three ways to select items in a listbox by using the mouse by using the arrow keys or by typing part of the name of the option you want e Mouse Use the Operating tool to select items With the Multiple Selection Listbox you can select more than one item by lt Shift gt clicking on additional items G Programming Reference Manual 13 2 National Instruments Corporation Chapter 13 List and Ring Controls and Indicators e Arrow keys Use the arrow keys to select items To add the currently highlighted option to the list of selected items press the spacebar You can deselect a currently selected option by using the arrow keys to move to the option and then pressing the spacebar e Typing part of the name of the option you want Type the name of the option to select the item You also can use the left or right arrow keys to go to the previous or next items that match the typed letters Listbox Data Types The data type for a Single Selection Listbox is Int32 The data value for the Single Selection Listbox is a number that represents the currently selected option with the first option having a value of zero If no option is selected the value is 1 The Multiple Selection listbox is an array of Int32s where the value s in the array represent the currently selected option s If no option is selected the value is an empty array Listbox Pop Up
84. a bitmap draw all data for that page into the bitmap and then send the bitmap to the printer This method takes longer to print than the other two but can yield a more accurate representation of the text and fonts than standard printing even though the printout is not as high resolution as with PostScript printing The bitmap image is in color for color printers and black and white otherwise Note Changes to options in the Printing Preferences dialog box take effect immediately History Preferences As explained in Chapter 25 Managing Your Applications each VI has a History window that displays the development history of the VI With the History Preferences dialog box you can choose the default settings for the History window of new VIs National Instruments Corporation 7 17 G Programming Reference Manual Chapter 7 Customizing Your G Environment The History Preferences dialog box is shown in the following illustration History do C Add an entry every time Vl is saved C Prompt for comment when Vl is closed C Prompt for comment when VI is saved C Record comments generated by C Show revision number in titlebar Login automatically with the registration name Login automatically with the system user name Show the login prompt at startup time The options in the History dialog box are divided into two groups The first group contains five options for indicating when and how entries to the History wi
85. a physical quantity for the double precision width unitsm s each group represents a 16 bit word 000E 001A 0002 0002 FFFF 0003 0001 OOOE indicates 14 bytes total 0x1A indicates that these are double precision width units 0002 indicates two base exponent pairs G Programming Reference Manual A 10 National Instruments Corporation Appendix A Data Storage Formats 0002 denotes the seconds base index FFFF is the exponent of seconds 0003 denotes the meters base index 0001 is the exponent of meters iz Note All physical quantities are stored internally in terms of base units regardless of what unit they are displayed as Table 9 2 Base Units shows the nine bases which are represented by indices 0 8 for radians candela Array The type code for an array is 0x40 Immediately after the type code is a word containing the number of dimensions of the array Then for each dimension an unsigned long integer contains the size in elements of that dimension Finally after each of the dimension sizes the type descriptor for the element appears The element type might be any type except an array The dimension size for any dimension might be FFFFFFFF 1 This means that the array dimension size is variable Currently all arrays are variable sized The actual dimension size is stored with the data The dimension size is always greater than or equal to zero The following is a type descriptor for a one dimensional array of doubl
86. a tunnel a wire connection normally is maintained between the tunnel and the wired node as shown in the following illustration G Programming Reference Manual 17 8 National Instruments Corporation Chapter 17 Wiring the Block Diagram Moving a tunnel sometimes creates an extra wire segment that lies beneath the structure border however You cannot select and drag this segment because it is hidden but it disappears if you drag the segment National Instruments Corporation 17 9 G Programming Reference Manual Chapter 17 Wiring the Block Diagram Wiring Off Screen connected to it as shown in the following illustration If you are unsure about which wire is connected to a tunnel triple click on the wire To select the parts of a wire inside and outside a loop structure at the same time select the part of the wire on one side of the structure and hold down the lt Shift gt key while you select the part of the wire on the other side of the structure You can add an object to a group of previously selected objects by holding down the lt Shift gt key while you select the new object Also you can drag a selection rectangle around both parts of the wire The structure is not selected unless you completely surround it with a selection rectangle Other nodes need only to touch the rectangle to be selected If a block diagram is too large to fit on the screen you can use the scrollbars to move to an off screen area and drag the
87. advantage of a CVI driver if one exists Given the option however a true G driver consisting of G diagrams is preferable because it is easy for customers to view and modify and because it multitasks well within the G environment Library calls are synchronous so any VIs running in parallel pause for the duration of the call Conversion Process If you select File Convert CVI FP File a dialog box appears asking you to select a LabWindows CVI Function Panel file When you have selected an FP file you see the following dialog box in which you can indicate where to save new VIs and what driver functions to convert G Programming Reference Manual 23 8 National Instruments Corporation Chapter 23 Calling Code from Other Languages CY I Function Panel Converter Select a Destination Directory or YI Library C 4PPLICATSCVIFILS SFL45 LLB Browse Instrument Prefix FL45 Select Function Panel Items to Process Double click on an item to toggle selection I x Initialize o Application Functions Set Up amp Read Measurements Configuration Functions Configure Measurements Configure Range Configure Trigger Options x a Configure Modifiers x Config Compare Config Hold Cancel You specify the destination directory or VI library in the topmost text box The suggested destination is shown and you can change the path to place the new VIs that G creates anywhere you want You can us
88. amount of time from each channel Then you need to use this data structure because each row of a two dimensional array must have the same number of elements but the number of elements in the interior arrays of an array of clusters can vary G Programming Reference Manual 15 6 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators The following illustration shows how to create the appropriate data structure from two arrays To see an example of this concept look at the Waveform Graph VI in the general examples general graphs gengraph 1llb directory Another way to convert arrays into elements of an array of clusters is to use the Build Cluster Array function The fourth data type is a cluster of an initial x value a Ax value and an array of clusters of an array of y data Use this data structure instead of a two dimensional array if the number of elements in each plot is different For example if you need to sample data from several channels but not for the same amount of time from each channel Then you need to use this data structure because each row of a two dimensional array must have the same number of elements but the number of elements in the interior arrays of an array National Instruments Corporation 15 7 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators of clusters can vary The following diagram illustrates how you can create this kind of d
89. an edit mode and a customize mode the current mode is indicated by a button in the toolbar as shown to the left of this text A Control Editor is in edit mode when it first opens In edit mode you can change the size or color of a control and select options from its pop up menu just as you do in edit mode of any front panel In customize mode you can change the parts of a control individually Customize mode is described in detail later in this chapter G Programming Reference Manual 22 2 National Instruments Corporation Chapter 22 Custom Controls and Type Definitions After you have edited a control you can use it in place of the original control on the front panel that you were building when you opened the Control Editor You also can save it to use on other front panels Applying Changes from a Custom Control not OK button When you are ready to replace the original front panel control with your new custom control select File Apply Changes from the main menu of the Control Editor AS Edit Operate Pro The file dialog box appears asking you to name and select a location for your custom control If your original front panel is the only place you use the custom control you can close the Control Editor window without saving the control Be sure to save the original VI with the custom control in place to preserve your work If you want to use the custom control on other front panels in the future you must save it as described
90. and dialog box options to a final action The sequence File Page Setup Options Substitute Fonts directs you to pull down the File menu select the Page Setup item select Options and finally select the Substitute Fonts option from the last dialog box G Programming Reference Manual xxiv National Instruments Corporation About This Manual paths Paths in this manual are denoted using backslashes to separate drive names directories and files as in drivename diriname dir2name myfile Warning This icon to the left of bold italicized text denotes a warning which alerts s7 you to the possibility of damage to you or your equipment VW Caution This icon to the left of bold italicized text denotes a caution which alerts you to the possibility of data loss or a system crash Note This icon to the left of bold italicized text denotes a note which alerts you to important information Abbreviations acronyms metric prefixes mnemonics symbols and terms are listed in the Glossary Related Documentation The following documents contain information that you might find helpful as you read this manual BridgeVIEW User Manual Online Reference available through the Help menu in LabVIEW or Bridge VIEW LabVIEW Tutorial Manual LabVIEW Instrument I O VI Reference Manual LabVIEW Code Interface Reference Manual LabVIEW Communications VI Reference Manual Customer Communication National Instruments wants to rec
91. and dialog box options To display the window choose Show Help from the Help menu or press lt Ct r1 h gt Windows lt command h gt Macintosh lt met a h gt Sun or lt Alt h gt HP UX If your keyboard has a lt Help gt key you can press that key instead Move your cursor onto the icon of a function a subVI node or a VI icon including the icon of the VI you have open shown at the top right of the VI window to see the help information Selecting Help Lock Help or clicking on the lock icon at the bottom of the window locks the current contents of the Help window When you have locked it moving over another function or icon does not change the display in the Help window Select Lock Help or click on the lock icon again to turn this option off Front Panel Help When you move the cursor over a control or indicator the Help window displays the description for that particular control or indicator It is a good idea to enter descriptions for all controls and indicators when you create a VI See the Creating Object Descriptions section of Chapter 2 Building VIs for information If you hold the cursor on a VI icon in the top right of a front panel for a few moments the Help window displays help for that VI Block Diagram Help For functions and subVI nodes the Help Window also displays the icon inputs and outputs as well as a description of the functionality of the node You can display the Help window as either
92. appendices glossary and index xxiii xxiv basic G concepts xxi xxii block diagram programming xxii xxiii front panel objects xxii G Programming Reference Manual documentation options VI Setup dialog box 6 3 to 6 4 See also descriptions Add an entry every time this VI is saved 6 4 Help Path box 6 4 Help Tag box 6 4 illustration 6 3 Prompt for comment when this VI is closed 6 4 Prompt for comment when this VI is saved 6 4 Use History Defaults In Preferences Dialog 6 3 dots at wire junctions showing 7 11 double numeric data storage format A 2 Double Click Attribute 20 13 to 20 14 double precision representation 64 bit DBL 9 4 dragging and dropping VIs pictures and text 2 8 to 2 9 dropper tool Icon Editor 3 3 drop through clicks allowing 7 23 Duplicate Case command 18 20 duplicating objects 2 12 to 2 13 E Edit Control amp Function Palettes option 7 24 22 16 Edit Control option 22 1 to 22 2 Edit Icon option 3 2 3 21 Edit menu Clear 2 13 Copy 2 12 Cut 2 12 Edit Control 22 1 to 22 2 Edit Control amp Function Palettes 7 24 22 16 Move Backward 2 11 Move Forward 2 10 Move to Back 2 11 Move to Front 2 10 Panel Order 8 8 to 8 9 National Instruments Corporation Paste 2 12 Remove Bad Wires 4 10 17 6 17 11 17 14 SubVI From Selection 3 10 User Name 7 19 to 7 20 Edit Palettes dialog box 7 26 to 7 27 Edit VI Library option 2 30 editing VIs aligning objects 2
93. applications iP Note When writing data to a file for use by an application other than G you might need to transform your data after flattening it Other Windows G Programming Reference Manual A 12 National Instruments Corporation Scalars Appendix A Data Storage Formats applications typically expect numeric data to be in little endian form least significant byte first Other Windows and Macintosh applications typically expect extended precision floating point numbers to be in the 80 bit and 96 bit formats described previously respectively The Flatten to String and Unflatten from String block diagram functions described in the G Function Reference online help use the internal flatten and unflatten functions The flattened form of any numeric type as well as the Boolean type contains only the data in big endian format For example a long integer with value 19 is encoded as FFFF FFED A double precision floating point number with a value approximately equal to 4is OX 40 09 21 FB 54 44 2D 18 A Boolean True is 8xxx 9xxx EXXX or FXXX The file form for extended precision numbers is based on the SPARC quadruple precision form which is a 16 bit biased exponent followed by a mantissa which is 112 bits long The Macintosh and PC have an explicit bit the bit left of the binary point In normalized numbers this bit is always a one It is only a zero when the exponent is zero very small denormalized numbers On
94. arrays vs other systems 14 16 to 14 19 graph array example 14 2 to 14 3 index display array shell 14 5 displaying array in single element or tabular form 14 9 to 14 11 interpreting 14 8 to 14 9 pop up menu 14 7 indexes 14 1 to 14 2 moving 14 14 moving between elements of arrays 14 13 multidimensional 14 4 one dimensional 14 3 14 10 operating 14 11 to 14 16 resizing 14 14 selecting cells 14 14 to 14 16 string array example 14 2 tabbing between elements 14 13 three dimensional 14 11 two dimensional 14 3 14 8 type descriptors A 11 waveform array example 14 2 two dimensional example 14 3 to 14 4 when to use 14 4 National Instruments Corporation Index Attribute Nodes 20 1 to 20 15 See also attributes purpose and use 18 7 to 18 8 running out of memory note 18 9 National Instruments Corporation avoiding cycles in subVIs Attribute Nodes in Case Structures 3 13 Attribute Nodes within loops 3 12 creating 20 1 to 20 6 associating terminal with attribute 20 4 more than one node 20 4 to 20 5 reading or setting attributes 20 2 to 20 3 examples Booleans 20 11 to 20 12 changing plot color on chart 20 10 to 20 11 examples in examples 11b 20 6 listbox controls 20 13 to 20 14 presenting options to users 20 14 reading cursors programmatically 20 14 to 20 15 ring controls 20 12 to 20 13 setting strings of ring control 20 12 to 20 13 Find pop up menu 3 29 help informat
95. available for the Macintosh It is used only when you open a device in one VI but want to perform I O on the device in another VI i Note You rarely need to use a Device RefNum control on your front panel These controls are used in the Instrument I O VIs in vi 1ib to access the G GPIB and serial device drivers You only need to use a Device RefNum control if you have to write a special purpose G device driver for the Macintosh The Network Connection RefNum is used with the TCP IP VIs You generally use it when you open a network connection in one VI but want to perform I O on the network connection in another VI The Occurrence RefNum is used with the occurrence functions You use it only when you generate an occurrence in one VI but want to set or wait for the occurrence in another VI The following illustration shows the front panel and block diagram of a VI that uses and returns an Occurrence RefNum generated in another VI Occurrence Occurrence Occurrence Occurence RefNum In RefNum Out RefNum In RefNum Out l L zet occurences front panel block diagram G Programming Reference Manual 12 4 National Instruments Corporation Chapter 12 Path Controls and Indicators and Refnums The following illustration shows the front panel and block diagram of a VI that uses and returns a Byte Stream File RefNum generated in another VI Byte Stream Byte Stream Byte Stream File RefNum Inj File RefNum Out File RefNum In Fi
96. bars or no bars at all The Fill Baseline option sets what the baseline fills to Zero fills from your plot to a baseline generated at 0 Infinity fills from your plot to the positive edge of the graph Infinity fills from your plot to the negative edge of the graph By using the bottom portion of this menu you can select a specific plot of this graph to fill to The Interpolation option brings up the palette shown in the following illustration in which you choose how the graph draws lines between plotted points The first option does not draw a line making it suitable for a scatter plot The option at the bottom left draws a straight line between plotted points The two stepped options which link points with a right angled elbow are useful for creating histogram like plots The National Instruments Corporation 15 21 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators option at the top right plots the y axis first although the option at the bottom right plots the x axis first Fill Baseline Interpolation The Color option displays the palette for selecting the plot color You also can color the plots on the legend with the Color tool and you can change the plot colors while running the VI To change the properties of highlighted text use the Font ring in the toolbar Waveform Charts The waveform chart is a special type of numeric indicator that displays one or more plots Charts are
97. because you saved the VI without entering a comment This is not a problem In fact the revision number is useful because it is independent Suppose you receive a copy of a VI from another user Later you want to know if the other user updated the VI since you received your copy You can easily tell by looking at the revision numbers even if the other user made a change without adding comments If the revision number only changed when you added a comment it would be a comment number not a revision number The revision number is even more effective when combined with the history If users have been adding comments to the history you can tell what changes were made since you last received a copy Resetting History Information Under the comment box there is a button labeled Reset Pressing Reset erases the history and optionally resets the revision number to zero This is useful when you copy a VI and want to start the new VI with a clean slate no history Because the history is strictly a developer tool the history is removed automatically when you remove the block diagram of a VI The History window is not available in the run time version but the revision number is available in the VI Information dialog box even for VIs that have had their block diagrams removed You can remove the revision number using the Reset button to reset the history of your VI before you remove the block diagram G Programming Reference Manual 25 8 Natio
98. border and enable auto indexing on the input tunnel components of that array enter the loop one at a time starting with the first component The loop indexes scalar elements from one dimensional arrays one dimensional arrays from two dimensional arrays and so on The opposite action occurs at output tunnels elements accumulate sequentially into one dimensional arrays one dimensional arrays accumulate into two dimensional arrays and so on National Instruments Corporation 18 7 G Programming Reference Manual Chapter 18 Structures The following illustration shows the appearance of tunnels on the loop structure borders with and without auto indexing The wire becomes thicker as it changes dimensions at the loop border Textil Enable Indexing Create Constant Create Control Create Indicator You often use For Loops to process arrays sequentially For this reason array tunnels have auto indexing enabled by default when you wire an array into or out of a For Loop While Loops are not commonly used for that purpose so they are not enabled for auto indexing by default To enable or disable auto indexing on a tunnel on the loop border you must pop up on the tunnel at the loop border and choose Enable Indexing or Disable Indexing Auto Indexing for Setting the For Loop Count When you begin auto indexing on an array entering a For Loop it automatically sets the count to the size of the
99. com Fax 03 9879 6277 0662 45 79 90 19 02 757 03 11 905 785 0086 514 694 4399 45 76 26 02 90 502 2930 01 48 14 24 14 089 714 60 35 2686 8505 03 5734816 02 41309215 03 5472 2977 02 596 7455 5 520 3282 0348 430673 32 84 86 00 2265887 91 640 0533 08 730 43 70 056 200 51 55 02 737 4644 01635 523154 Technical Support Form Photocopy this form and update it each time you make changes to your software or hardware and use the completed copy of this form as a reference for your current configuration Completing this form accurately before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently If you are using any National Instruments hardware or software products related to this problem include the configuration forms from their user manuals Include additional pages if necessary Name Company Address Fax Phone Computer brand Model Processor Operating system include version number Clock speed MHz RAM MB Display adapter Mouse __ yes ___no Other adapters installed Hard disk capacity MB Brand Instruments used National Instruments hardware product model Revision Configuration National Instruments software product Version Configuration The problem is List any error messages The following steps reproduce the problem Hard
100. complete execution With nested While Loops how do stop both loops without anything in the outer loop executing after the inner loop stops Put the code you do not want to execute on the last iteration into a Case Structure It is best if the condition terminal of the inner loop is connected to the selection terminal of the Case Structure What is Panel Order Edit Panel Order determines the order of the objects on the front panel In other words if you were using lt Tab gt on the keyboard to move between objects the key focus would change from object to object in the order determined by the panel order Only controls can receive key focus the lt Tab gt key does not switch focus to indicators By default the panel order is the order in which you create objects on the front panel With front panel data logging the panel order determines the order in which the different objects are compacted into a cluster within the file National Instruments Corporation B 13 G Programming Reference Manual Appendix B Common Questions about G How can I have LabVIEW or BridgeVIEW to launch a particular VI automatically By default LabVIEW and BridgeVIEW launch and create an Untitledl vi You might want your application to launch a particular VI automatically You also can set the VI to run when loaded so that launching Lab VIEW or BridgeVIEW not only opens your VI but also starts running it Set the appropriate Execution Options in
101. contain subdirectories or folders e Loading and saving files are faster from the file system than from VI libraries Less disk space is required for temporary files during the load and save processes e Storing VIs and controls in individual files is more robust than storing your entire project in the same file Keep in mind that many of the VIs shipped with G are shipped in VI libraries so that they are stored in consistent locations on all platforms National Instruments Corporation 2 29 G Programming Reference Manual Chapter 2 Building Vis Creating VI Libraries To create a VI library take the following steps 1 Select Save Save as or Save a Copy As from the File menu 2 Macintosh If G is configured through Preferences Miscellaneous to use native file dialog boxes click on Use LLBs in the dialog box that appears 3 In the dialog box that appears after step 1 or step 2 click on the New or the New VI Library button 4 Inthe dialog box that appears enter the name of the new library and click on the VI Library button G adds a 11b extension to the name of the library automatically if you do not 5 A dialog box appears ready for you to name your VI if you wish and save it in the new library Saving in Existing VI Libraries When you have created a VI library you can save new VIs in it just as if it were a directory After selecting one of the Save options from the File menu the name of your libr
102. control or constant to drop the full pathname of the VI inside the control or constant G Programming Reference Manual 2 8 National Instruments Corporation Chapter 2 Building Vis You can use the following Drag and Drop capabilities externally from other applications to G objects e Drag a file into a path control or constant to drop its full pathname e Drag a datalog file into a Data Log File Refnum to create a cluster containing the data structure in the datalog file e Drag a graphics file into a Pict Ring front panel or block diagram to drop the picture it contains e Drag a VI file into the block diagram of a VI to drop it as a subVI e Drag a custom control file into the front panel to drop the custom control stored in that file e Windows 95 NT Drag Text from an OLE source to drop its text into a string control or constant front panel block diagram or label e Windows 95 NT Drag Image from an OLE source to drop its picture into a picture ring front panel or block diagram e Macintosh Drag a Text Clipping or text selected from any application to drop that text into a string control or constant front panel block diagram or label e Macintosh Drag an Image clipping or an image selected from another application to drop it into a picture ring front panel or block diagram Note If you can drop an object successfully the destination is highlighted For more information on Drag and Drop features
103. different from graphs in that charts retain previous data up to a maximum which you can define New data is appended to the old data letting you see the current value in context with previous data For an example of a waveform chart see general examples general graphs charts 1lb Waveform Chart Data Types You can pass charts either a single value or multiple values at a time As with the waveform graph each value is handled as part of a uniformly spaced waveform with each point spaced one point from the previous one along the x axis You can pass either a single scalar value or an array of multiple values to the chart The chart handles these inputs as new data for a single plot G Programming Reference Manual 15 22 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators Following are diagrams illustrating how you can use the chart for each of these kinds of data remp Fee You receive the best performance from a chart when you pass it multiple points at a time because the chart has to be redrawn only once for each waveform instead of once for each point You can pass data for multiple plots to a waveform chart in several ways The first method is to bundle the data together into a cluster of scalar numerics where each numeric represents a single point for each of the plots An example of this is shown in the following illustration National Instruments Corporation 15 23 G Programm
104. display on a slide knob meter or chart There is no difference between the digital display and the ordinary front panel National Instruments Corporation 22 15 G Programming Reference Manual Chapter 22 Custom Controls and Type Definitions digital control except that the digital display is serving as part of another control The digital display is also made up of parts When you are editing the original control in the Control Editor the digital display behaves as a single part so you cannot change or move its parts individually You can however open the Control Editor for the digital display and customize it there To customize a control that is a part of another control open the Control Editor for it You can open the Control Editor window for the part directly from the original front panel if it can be selected separately from the main control in edit mode The digital display can be selected separately from the slide control for example Then you can choose Edit Edit Control amp Function Palettes You always can open the Control Editor window for the part from the Control Editor window of the main control Select the part in the Control Editor and choose Edit Edit Control amp Function Palettes Control editors can be nested in this way indefinitely but most controls use other controls as parts only at the top level An exception is the graph which uses complicated controls as parts which in turn use other cont
105. during launch Abortifless than KBytes 500 Use default Warn if less than KBytes 2000 Use default Except for the Deallocate memory as soon as possible option changes to the Performance amp Disk options take place when you restart your computer The options in this dialog box are as follows Deallocate memory as soon as possible Forces G to deallocate the memory of a VI after it completes execution Doing this can improve memory usage in some applications because subVIs deallocate their memory immediately after executing However it probably slows performance because G has to allocate and deallocate memory more frequently Note Changes to the Deallocate memory as soon as possible option take effect immediately Windows 3 1 Use default timer The timing functions in G use the built in Windows timer This timer has by default a resolution of 55 ms it increments 18 times a second This means that the Tick Count Wait and Wait Until Next ms Multiple VIs in G only have 55 ms resolution Notice however that you can specify more accurate timing National Instruments Corporation 7 7 G Programming Reference Manual Chapter 7 Customizing Your G Environment rates to the DAQ VIs because they use the built in timers of the DAQ boards to control the acquisition rate You can increase the resolution of the Tick Count Wait and Wait Until Next ms Multiple VIs to 1 ms by increasing the resolution of the built in timer of Win
106. entorn EE ERES Se Sinn E A EAE TREER E en RE eaweaioet 26 12 Virtual M MOry ssns e a E E E S 26 12 Macintosh Memory soen aarnior sores A E 26 13 VI Component Memory Management 0 cece ces eeeeeeeseeeeeeseeesecaeesaecaeeaes 26 13 Dataflow Programming and Data Buffers 00 0 0 eee eee ce ceeeeeeeeeeeeeeeneeeneeaee 26 14 Monitoring Memory Usage cseessecseceseeseceseesecesceseseeeeseseaseaeeeneaee 26 17 Rules for Better Memory Usage 0 eee ceeeseceeceseeseceseeseceseeeeeeeeeeseeseaeeeaeenee 26 18 Memory Issues in Front Panels 0 cece ceseeeecesceseeeeeeeeeeeeeseeeneenee 26 19 SubVIs Can Reuse Data Memory eee cseceecneceeeteeeeenseeneees 26 20 Local Variables Cannot Reuse Data Memory eeeeceeeeeeeeeeeeeeee 26 20 Global Variables Always Keep Copies of Their Data 0 26 21 Understanding When Memory Is Deallocated 00 00 26 21 Determining When Outputs Can Reuse Input Buffers 0 0 0 0 26 22 Consistent Data Types siisii erre aio i E E vig E E T 26 22 How to Generate Data of the Right Type eee 26 23 Avoid Constantly Resizing Data eee eee ceecereeees 26 24 Example 1 Building Arrays tect eeeeeeeceseeseceeeeeeeneees 26 24 Example 2 Searching through Strings eee 26 27 Developing Efficient Data Structures oo eee ceeese cee ceseeeeceseeeeceeeeeeseneeeeeens 26 28 Case Study 1 Avoiding Complicated Data Types eee eeeeeeeseseeeeeeees 26 30 Case Study 2 Global Table of Mixed Data Type
107. ess secebes phe actos ds scessevasesstsveesseesoadesexenscsdecs 16 8 SMUCTULES sibs a eee E EAE EEE E RENE E s 16 11 Replacing and Inserting Block Diagram Objects 00 0 0 cece ce ceseeeeeeseeeeeeeeeeeeeneeeeene 16 12 Adding Constants Controls and Indicators Automatically 0 0 eee eeeeeeeeeeeeeeeeeeeene 16 13 Chapter 17 Wiring the Block Diagram Wiring Fechmi que EAEE EET vues ciatvabeen sdsvastagsteas denatesuavocsscastotnms 17 1 Wire Stretching neinei e ees auld wee EEEE E EE 17 5 Selecting Moving and Deleting Wires sssesesseseseesseeeeserereersresrsessrrrrrrereeesse 17 6 Witing Off Screen ieoor eseese a ob he cies ea EOE AE ESS 17 10 Solving Wiring Problems cccsscsssesseoncesesensvecsseessesssescnnsesnsonesesenees rhe 17 11 Bad Wt 2ceh sch co esses eens E crest E E E EE a o a E a 17 11 Wire Type Dimension Unit or Element Conflict 17 12 Multiple Wire Sources 20 eect cece eeeecee cee ceneceecneeeeeeeeeees 17 13 NO Wire SOUT E 2 s5ccsssct sect laces ssa chests sceudetcessscuensepehsbttesced 17 13 Loose Ends 3 atts sudan Sinisa tien ahead 17 14 Wire StUDS isenip ieies riisci iai rieri SE 17 14 Wire Cycles ennio neooni GA A a eee 17 15 Wiring Situations to Avold 0 eee eee eeeeceecseesseeeeeeceeeeseeseecaecsaeseceeessenseenes 17 15 POOPING WALES eoi heel hide ean E n e E a Hatches 17 15 Hidden Wire Segments ovi scecssscestevasecststsccessbensbuseosssenssisnsnssceeabesess 17
108. file dialog boxes in G so that they look similar to those of other applications on your machine with a few exceptions discussed at in the next paragraph When this preference is not selected G uses its own platform independent file dialog boxes which add some convenient features such as providing a list of recent paths and reducing the steps necessary to save VIs in VI libraries In a few cases the native file dialog box of the operating system does not have the functionality required by G In such cases G uses its own file dialog box even when this option is selected On the Macintosh if you wire the pattern input or if you wire the datalog type input and use a select mode of 1 select new file 2 select new or existing file 4 select new directory or 5 select new or existing directory G uses its own file dialog box In Windows even if you wire the pattern input G uses its own file dialog box G Programming Reference Manual 7 22 National Instruments Corporation Chapter 7 Customizing Your G Environment Windows Macintosh Allow drop through clicks You can set G so that clicking only once on the mouse activates and selects an object in an inactive window This reduces the number of mouse clicks required from two to one Normally the first click activates the window and the second click passes through as a click in the window Use hot menus With this option you can navigate the menus using the mouse without keepi
109. follows e Search in VI s Indicates whether to search the front panel of a VI block diagram Get Info text or History window text At least one of these must be checked e Search in Object s Label Indicates whether to search visible or hidden object name labels e Search in Object s Data amp Parts Indicates if you need to search visible or hidden data and parts The data and parts of an object consist of everything belonging to an object except for the name label of the object You also have the option of searching the description of various objects At least one of the options in the Search in Object s Label and Search in Object s Data amp Parts must be checked Note The Text Search options are saved from search to search therefore if you do not find a string of text that is expected to exist make sure that the Text Search Options are set appropriately Narrowing the Search Scope Three options in the Search Scope ring menu indicate the VIs to be searched e All VIs in Memory Indicates the search scope as all VIs that currently are loaded Two checkboxes are available to include or exclude VIs in vi 1ib and the Hierarchy window National Instruments Corporation 3 27 G Programming Reference Manual Chapter 3 Building SubVIs e Selected VIs Selects a custom set of VIs to search The Hierarchy window can be included or excluded from the search scope The Select button brings up the Select VIs opti
110. for a path control on your VI In this way you can detect when the user has not entered a path in which case the user can use a file dialog box for choosing a path The Path amp Refnums palette contains several refnum controls shown in the following illustration These refnums generally are used to identify I O operations G has seven refnum data types for various kinds G Programming Reference Manual 12 2 National Instruments Corporation Chapter 12 Path Controls and Indicators and Refnums of I O For each refnum there is a corresponding control The following illustration shows the different kinds of refnums Byte Data Device Occurrence Network Stream Log RefNum RefNum Connection File File RefNum RefNum RefNum s Ge O B VISA VISA Session Address RefNum RefNum WISA To open a file you must specify the path of the file you want to open Because you can open more than one file at a time you need to indicate which operations apply to which open file The path control is not sufficient for this because you can open one file more than once concurrently When you open a file G returns a refnum that identifies that file You use this refnum in all subsequent operations that relate to that file You can think of this refnum as a unique number produced each time you open a file to identify it When you close the file the refnum is disassociated from it Note You only need to use a refnum control or indicator if yo
111. for comment when VI is closed 7 19 Prompt for comment when VI is saved 7 18 to 7 19 Record comments generated by the editor 7 19 Show revision number in titlebar 7 19 Show the login prompt at startup time 7 19 to 7 20 Horizontal Centers alignment 2 12 Horizontal Hierarchy option 3 18 Horizontal Layout button 3 19 hot menus 7 23 Huge pointer note 23 6 Icon Description Panel and Diagram format option 5 3 Icon and Description option 5 5 VI Connector and Icon 5 5 VI Description 5 5 Icon Editor Cancel button 3 4 illustration 3 2 OK button 3 4 tools available 3 3 to 3 4 Undo button 3 4 icons creating for controls 22 5 creating for subVIs 3 2 to 3 4 black and white vs color icons 3 3 Cancel button 3 4 cutting copying and pasting icons note 3 4 dropper tool 3 3 G Programming Reference Manual Index Edit icon option 3 2 fill bucket tool 3 3 filled rectangle tool 3 4 foreground background tool 3 4 Icon Editor 3 2 line tool 3 3 OK button 3 4 pencil tool 3 3 rectangle tool 3 3 select tool 3 4 text tool 3 4 Undo button 3 4 default icon 1 6 overview 1 6 printing Icon and Description option 5 5 Import at Same Size option 22 11 Import Picture After option 13 9 Import Picture Before option 13 9 Import Picture option 13 9 22 10 to 22 11 importing graphics See also pictures Boolean controls and indicators 10 6 controls 8 10 to 8 11 ring controls 13 9 Include G
112. history does not National Instruments Corporation 25 5 G Programming Reference Manual Chapter 25 Managing Your Applications Note provide a method for comparing two VIs to detect differences G saves the history as part of the VI It consists of a series of comments entered by those users who have made changes to the VI Unless you have selected the Record comments generated by LabVIEW option in either the VI Setup Documentation or the Edit Preferences History dialog box the comments in a VI history are not automatically created Anyone who makes changes to the VI must type in the information and keep the history up to date The History window is available when you are editing the VI by selecting Windows Show History or pressing the key equivalent lt Ctrl y gt Windows lt command y gt Macintosh lt met a y gt Sun or lt Alt y gt HP UX The following illustration shows an example History window Widget Calculator vi History User Hame johann Hext Revision 4 Comment Added code for the new widgets rev 3 Mon Mar 14 1994 11 32 23 AM johann Added descriptions to all Vl s in the Widget library rev 2 Mon Mar 14 1994 11 51 40 AM johann Added support for multiple foos rew 1 Mon Mar 14 1994 11 50 29 AM johann Converted all widget l s to LY 3 1 As you edit the VI you can type a description of important changes into the Comment box near the top of the window When you are finished making c
113. i Multiframe Numeric Case Structure Case Structure 10 0 O w OOo O Single Frame Multiframe Sequence Structure Sequence Structure Structures behave like other nodes in that they execute automatically when their input data is available and they supply data to their output wires only when execution completes However each structure executes its subdiagram according to the rules described in the following sections A subdiagram is the collection of nodes wires terminals and space that resides within the structure border The For Loop and While Loop each have one subdiagram The Case and Sequence structures however can have multiple subdiagrams stacked like cards in a deck with only one G Programming Reference Manual 18 2 National Instruments Corporation Chapter 18 Structures visible at a time You construct subdiagrams the same way that you construct the top level block diagram subdiagrams can contain block diagram terminals nodes including other structures and wires You create terminals for passing data into and out of a structure automatically where wires connecting outside nodes and inside nodes cross the structure boundary These boundary terminals are called tunnels Tunnels always have one edge exposed to the inside of the structure and one edge exposed to the outside A tunnel always resides on the border of the structure but you can move it anywhere along that border by dragging it with the Positioning too
114. in mind that data leaves the structure only when it completes execution entirely not when the individual frames finish Data at input tunnels is available to all frames as with Case Structures To pass data from one frame to any subsequent frame use a terminal called a sequence local To obtain a sequence local choose Add Sequence Local from the structure border pop up menu This option is not available if you pop up on a sequence local or over the subdiagram display window You can drag the terminal to any unoccupied location on the border Use the Remove command from the sequence local pop up menu to remove a terminal An outward pointing arrow appears in the sequence local terminal of the frame containing the data source The terminal in subsequent frames contains an inward pointing arrow indicating that the terminal is a source for that frame In frames before the source frame you cannot use National Instruments Corporation 18 17 G Programming Reference Manual Chapter 18 Structures the sequence local and it appears as a dimmed rectangle The following illustrations show the sequence local terminal 000000 Sequence local Sequence local cannot be used is sink of data Obooood Obooood Sequence local is Cannot wire an source of data input value to a sequence local that is a source Editing Case and Sequence Structures Because editing and manipulating the Case and Sequence structures involves similar techniques t
115. in the Saving Custom Controls section of this chapter The Apply Changes option is only available after you make changes to the control Apply Changes is disabled if there is no original control to update This happens when you delete or replace the original control when you close the original front panel or when you have opened a custom control that you saved earlier by selecting File Open Valid Custom Controls If the Control Editor has more than one control in it the not OK button appears A valid custom control must be a single control though it can be a cluster of other controls The not OK button appears temporarily while you move controls in and out of a cluster or array To see an National Instruments Corporation 22 3 G Programming Reference Manual Chapter 22 Custom Controls and Type Definitions explanation for the error click on the not OK button If there is more than one control in the Control Editor the error message reads There are extra objects on the front panel that do not belong to the custom control If there are no controls the error message reads There must be one control on the front panel for a custom control to be valid If you try to put a type definition control on the front panel of the Control Editor the error message reads You cannot use a Type Definition in the control editor unless it is inside another control such as a cluster or array See the Type Definitions section later in thi
116. keeping with the different platforms as described previously Custom font This checkbox is checked automatically if you change any font characteristics through the Font Style option Font Style Brings up a dialog box that lets you change font characteristics Note Changes to options in the Font Preferences dialog box take effect immediately For specific information on how the fonts are predefined or for information about the portability of fonts see the section Resolution and Font Differences in Chapter 27 Portability Issues National Instruments Corporation 7 15 G Programming Reference Manual Chapter 7 Customizing Your G Environment Printing Preferences The Printing Preferences dialog box is shown in the following illustration Keep in mind that some options are available on certain platforms only Preferences Fins 7 amp Standard printing C Allow printer dithering Scale printer fonts PostScript printing Bitmap printing Windows Macintosh Standard printing Directs G to format the VI print data front panel diagram icon etc and print it using standard drawing commands Use this option if you want to print to a file assuming your printer driver supports printing to a file if your printer does not have PostScript support or if you want your printer driver to do the PostScript translation instead of G Windows only Allow printer dithering Directs G to use printer dithe
117. libraries does not noticeably change regardless of the size of the VI library Another way to speed up the time it takes to save VIs whether or not they are in VI libraries is to make sure that your temporary directory is on the same drive partition in UNIX as your VIs You can copy files faster if the source and destination are on the same drive or partition If you use VI libraries you can emphasize the top level VIs by using File Edit VI Library from the menu option to mark certain VIs as top level G lists these files at the beginning of the file list in the file National Instruments Corporation 25 1 G Programming Reference Manual Chapter 25 Managing Your Applications dialog box There is no similar option for directories but you can emphasize your top level VIs by placing subVIs into subdirectories Backing Up Your Files Accidents happen Hard drives crash and file systems can become corrupt It is best to make a backup copy of your VIs at least once a week and preferably once a day You should copy them to another drive or to tape As an example of the problems that can occur one user accidentally corrupted the VI library that contained several weeks of work When prompted for a destination for a data file this user had selected his VI library at which point he wrote data over his own VI library Fortunately he was able to recover most of the contents of his VI library but only by good luck was it possibl
118. local variables accessing the same control with each having a different sense either read or write You use the age variable twice in the diagram once to write to and another time to read from Read from age current age Be careful to sequence the access to local variables or global variables so you can produce the results you want as in the preceding example There is no guarantee that the Write to age will occur before the Read from age if you do not create the proper sequencing yourself National Instruments Corporation 21 5 G Programming Reference Manual Chapter Custom Controls and Type Definitions This chapter introduces custom controls and type definitions You can customize a front panel control or indicator to make it better suited for your application For example you might want to make a Boolean switch that shows a closed valve when the switch is off and an open valve when the switch is on a slide control with its scale on the right side instead of on the left or a ring control with predefined text or picture items You can save a control or indicator that you have customized in a directory or VI library just as you do with VIs Then you can use this control on other front panels You also can create an icon for your custom control and have the name and icon of the control appear in the Controls palette If you need the same control in many places in your VIs you can create a master c
119. might be up to a few days wider depending on your time zone and if daylight saving time is in effect Autoscale Use AutoScale X or Y to turn the autoscaling option on or off Loose Fit Normally G rounds the end markers of the scale to whole numbers If you want the scales to be set to exactly the range of the data turn off the Loose Fit option in the graph pop up menu With a loose fit the numbers are rounded to a multiple of the increment used for the scale For example if the markers increment by five the minimum and maximum values are set to a multiple of five Panning and Zooming Options The Graph palette is included with any graph you drop onto the front panel This palette has controls for panning scrolling the display area National Instruments Corporation 15 17 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators i E of a graph and for zooming in and out of sections of the graph A graph with its accompanying Graph palette is shown in the following illustration If you press the x autoscale button shown at the left the graph autoscales the X data If you press the y autoscale button shown at the left the graph autoscales the Y data If you want the graph to autoscale either of the scales continuously click on the lock switch shown at the left to lock autoscaling on By using the scale format buttons shown left you can maintain run time control over the format
120. modify this label the same way you modify other labels To the right of the plot label is the plot sample Each plot sample has its own pop up menu to change the plot line color and point styles of the plot The array of points you wire to the graph are displayed with the characteristics you assign it in the graph legend The plot sample pop up menu is shown in the following illustration Common Plots Point Style Line Style Line Width Bar Plots Fill Baseline Interpolation Color i i i The Common Plots option helps you configure a plot for any of six popular plot styles including a scatter plot a bar plot and a fill to zero G Programming Reference Manual 15 20 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators plot Options in this subpalette are preconfigured for the point line and file styles in one step The Point Style Line Style and Line Width options display styles you can use to distinguish a plot The line width subpalette contains widths thicker than the default 1 pixel as well as the hairline option The latter option has no effect on the screen display but prints a very thin line if the printer and print mode support hairline printing Common Plots Point Style Line Style har Plots Fill Baseline Interpolation Color Note In Windows wide pens can be only in the solid style The Bar Plots option has a selection of vertical bars horizontal
121. moves the selected object in the stack to the top If object 1 is selected object 1 moves to the top of the stack with object 3 under it and object 2 on the bottom If object 2 is selected next Move To Front changes the order to object 2 on top object 1 under it and object 3 on the bottom Move Forward moves the selected object one position higher in the stack So starting with the original order of object 1 on the bottom of the stack and object 3 on top selecting this option for object 1 puts object 2 on the bottom object 3 on the top and object 1 in the middle G Programming Reference Manual 2 10 National Instruments Corporation Aligning Objects Chapter 2 Building Vis Move To Back and Move Backward work similarly to Move To Front and Move Forward except that they move items down the stack rather than up Select the objects you want to align and choose the axis along which you want to align them from the Alignment ring as shown at left The following illustration shows you how to select objects for alignment and the results of the selection Selecting objects for alignment by left edges BE Ol Sot Application Fon z ESE Fok You can align an object along the vertical axis using its left center or right edge You also can align an object along a horizontal axis using its top center or bottom edge Your selection becomes the current alignment option which is indicated by a dark border ar
122. not connect to a terminal These can result from wire stretching from retracing during the wiring process or from deleting wired objects Selecting Edit Remove Bad Wires disposes of loose ends Wire Stubs When you wire to a terminal you seldom click on the terminal when the cursor is exactly at its center When you are off center a wire segment automatically attaches itself from the click point to the terminal center If you then remove the wire going to the terminal a wire stub can remain causing a Broken Run button This problem is shown in the following illustration click point i terminal center lt 7 added segments i remnant left when you delete horizontal segment To avoid this situation triple click on a wire to make sure all portions are selected and then delete it You also can use Edit Remove Bad Wires to delete the stubs G Programming Reference Manual 17 14 National Instruments Corporation Chapter 17 Wiring the Block Diagram Wire Cycles Wires must not form cycles That is wires must not form closed loops of icons or structures as shown in the following illustration The execution system cannot execute cycles because each node waits on the other to supply it data before it executes The Shift Registers section of Chapter 18 Structures describes the correct way to feed back data in a repetitive calculation Wiring Situations to Avoid Note The following sections describe situa
123. now the maximum and can flip the scale so that what was formerly the maximum is now the minimum G also recalculates the increments e If you type into any intermediate marker the increment becomes that value minus the minimum e If you change the size of the slide the increment adjusts so that the markers do not overlap Selecting Non Uniform Scale Marker Distribution By default scale markers are evenly spaced If you want you can indicate exactly where inner markers for a scale are located This is useful for marking a few specific points on a slide such as a set point or threshold If you want non uniform marker distribution select Scale Marker Spacing Arbitrary from the pop up menu of the scale G Programming Reference Manual 9 16 National Instruments Corporation Chapter 9 Numeric Controls and Indicators Then you can pop up on the slide and select Scale Add Marker or pop up on the marker and select Add Marker A marker appears at an arbitrary location as shown in the following illustration To delete an arbitrary marker pop up on the slide and select Scale Delete Marker or pop up on the marker and select Delete Marker When a marker is created you can type a number in the marker the location changes automatically to match the number You also can move markers by dragging ticks the small lines beside the data points of the scale To do so idle the Operating tool over the ticks The cursor changes to show
124. object on the front panel a corresponding terminal is created on the block diagram You use this terminal if you want to read data from a control or to send data to an indicator National Instruments Corporation 2 3 G Programming Reference Manual Chapter 2 Building Vis If you select Windows Show Diagram you can see the corresponding block diagram for the front panel The block diagram contains terminals for all front panel controls and indicators Voltage Input 4 0 6 0 Voltage Input front panel block diagram Tools Palette A tool is a special operating mode of the mouse cursor You use tools to perform specific functions Many of the tools contained in the floating Tools palette are shown in the following illustration You can move this palette anywhere you want or you can close it temporarily by clicking on the close box the small box with an x that appears in the top right corner of palettes Once closed you can access it again by selecting Windows Show Tools Palette You also can bring up a temporary version of the Tools palette at the location of your cursor by clicking while pressing lt Ctrl Shift gt Windows lt command Shift gt Macintosh lt meta Shift gt Sun or lt Alt Shift gt HP UX G Programming Reference Manual 2 4 National Instruments Corporation Chapter 2 Building Vis The tools and their functions descriptions in the Tools palette are as follows Operating tool Places Co
125. objects 2 9 to 2 11 See also moving canceling move operation 2 10 moving forward 2 10 moving incrementally 2 9 moving to back and moving backward 2 11 moving to front 2 10 lt Shift gt key for restricting direction 2 9 Positioning tool 2 5 2 7 to 2 8 PostScript printing 5 2 7 16 to 7 17 precision of digital displays See Format amp Precision option preemptive multitasking 24 1 preferences See also VI Setup dialog box history information 25 9 storing 7 23 to 7 25 Preferences Dialog Box 7 1 to 7 25 Block Diagram Preferences dialog box 7 11 to 7 12 illustration 7 11 Show dots at wire junctions 7 11 Show subVI names when dropped 7 11 Show tip strips over terminals 7 11 Show wiring guides 7 11 Color Preferences dialog box 7 13 to 7 14 Blink Background 7 14 Blink Foreground 7 14 Block Diagram 7 13 Coercion Dots 7 13 Front Panel 7 13 illustration 7 13 Menu Background 7 14 Menu Text 7 13 G Programming Reference Manual l 44 Provide extra colors 7 14 Scrollbar 7 13 Use default colors 7 14 Debugging Preferences dialog box 7 12 to 7 13 Auto probe during execution highlighting 7 12 Show data bubbles during execution highlighting 7 12 Show warnings in error box by default 7 12 Warn about objects unavailable in student edition 7 12 Font Preferences dialog box 7 14 to 7 15 Custom font 7 15 Font style 7 15 illustration 7 15 Use default font 7 15 Front Panel Preferences dialog box 7
126. on the monitor Windows How do select bitmap printing Go to Edit Preferences and select Printing The last option on the screen is Bitmap printing Miscellaneous What is info LabVIEW and how do subscribe Info LabVIEW is a user sponsored and supported network of LabVIEW and Bridge VIEW users Users can post information to a specific e mail address see below the posting is then broadcast to all users subscribing to the list Other users then might respond back to the group or perhaps directly to the individual who wrote the post National Instruments Corporation B 9 G Programming Reference Manual Appendix B Common Questions about G Several power users as well as some National Instruments employees subscribe to the list and respond to various issues Overall the Info LabVIEW group has been received extremely well Although the group is not connected with National Instruments official responses are made on occasion to the group Most of the time the conversations take place strictly between G users Users who want to subscribe to the list should send e mail to this address info LabVIEW request pica army mil There are two ways for users to receive the postings the standard format and digest format Standard format means you receive the postings as they occur Digest format means you receive one package at the end of each day containing all postings for the day Indicate digest format in the e mail me
127. only feature BridgeVIEW has its own login security system in which the Edit User Name option does not appear User Login other Jo Zarb Lv Stephan Moore 0R j bancet You can switch to another user name the system user name or your application registration name in Windows or on the Macintosh or the system user name in UNIX without having to type it in by using the pull down menu shown in the preceding illustration You also can type in a name which appears in the list thereafter Windows NT Macintosh with file sharing only and UNIX Login automatically with the system user name Assuming that a user name has been defined causes G to use the system login name of the current user Note Changes to options in the History Preferences dialog box take effect immediately G Programming Reference Manual 7 20 National Instruments Corporation Chapter 7 Customizing Your G Environment Time and Date Preferences The Time and Date Preferences dialog box is shown in the following illustration Preferences TimeandDate z Default date format Month first M D Y Day first D M Y Year first M D Date Separator Default time format 12 hour AM PM 24 hour Military Time Time Separator C The options in this dialog box control the default displays of time and date in the digital displays of new controls and indicators You can override the defaults in this dialog box for individu
128. other programs or subprograms A VI within another VI is called a subVI The icon and connector of a VI work like a graphical parameter list so that other VIs can pass data to a subVI With these features G makes the best use of the concept of modular programming You divide an application into a series of tasks which you can divide again until a complicated application becomes a series of simple subtasks You build a VI to accomplish each subtask and then combine those VIs on another block diagram to accomplish the larger task Finally your top level VI contains a collection of subVIs that represent application functions Because you can execute each subVI by itself separate from the rest of the application debugging is much easier Furthermore many low level subVIs often perform tasks common to several applications so you can develop a specialized set of subVIs well suited to applications you are likely to construct The following sections further explain the front panel block diagram icon connector and other related features To view examples of different features that G uses for your LabVIEW or Bridge VIEW application refer to the examples directory if you are a LabVIEW user Paths specific to special features appear in corresponding folders under the general directory You can find these paths for special features in the appropriate chapters of this manual G Programming Reference Manual 1 2 National Instruments Corporati
129. pass arbitrary data structures to C code you can create a Code Interface Node CIN By using CINs you can call code written specifically to link to G VIs The CIN is a very general method for calling C code from G You can pass arbitrarily complex data structures to and from a CIN In some cases you might have a higher performance using CINs because data structures are passed to the CIN in the same format they are in when stored in G To have this level of performance however you must learn how to create a CIN This requires that you be a good C developer and take sufficient time to create the CIN you need Also because CINs are more tightly coupled with G there are restrictions on which compilers you can use G Programming Reference Manual 23 2 National Instruments Corporation Chapter 23 Calling Code from Other Languages If you are a LabVIEW user you can refer to the LabVIEW Code Interface Reference Manual for information on how to create Code Interface Nodes Call Library Function Windows UNIX Using the Call Library function directly you can call a Windows 3 1 16 bit DLL a Windows 95 NT 32 bit DLL a Macintosh Code Fragment or a UNIX Shared Library function directly Macintosh The Call Library function uses the Macintosh Code Fragment Manager CFM This is standard on all PowerMac machines 680x0 Macintosh computers need the CFM extension Additionally the Call Library Node on 680x0 Macintosh computers can
130. print option as described in the previous question Macintosh You can use the AESend Print Document VI to direct the other application to print a document The VI is located in Functions Communication A pple Event For more details see the section Using Alternative Printing Methods in Chapter 5 Printing VIs You also can use the programmatic print option as described in the previous question How do print all the data on a waveform chart The Waveform Chart only prints the displayed data when you print the front panel To print all the data in a chart including that in the history buffer first autoscale the x axis of the chart by popping up on the chart showing the chart palette and locking the x axis or setting the x axis programmatically through a chart Attribute Node Why does LabvlEW or BridgeVIEW crash when printing On Windows this crash might be related to the video driver See the question concerning random crashes on your platform in the section Error Messages and Crashes for information on how to proceed How do use PostScript printing If your printer works with PostScript language first install and use the PostScript printer driver for your printer Go to Edit Preferences Printing and select PostScript printing If you have a PostScript printer you can take advantage of the following benefits e PostScript printouts reproduce the image of the screen more accurately e PostScript facilitates high
131. remove files from the directories that you selected You can enable or disable the automatic update setting for a subpalette by selecting the Automatic Update From Directory pop up option This option actually creates menu palette files inside of each directory that is recursed into Select Link to a library if you want to link to the Controls palette or Functions palette that is a part of a VI library As with the previous G Programming Reference Manual 7 28 National Instruments Corporation How Views Work Chapter 7 Customizing Your G Environment setting the palette for a library automatically updates as you add files to the library Notice that you can mix VIs functions and subpalettes within a palette freely Also a palette can contain VIs from different locations Moving Subpalettes Because clicking on a subpalette opens it you cannot move a subpalette by dragging it To move a subpalette you can select the Move Submenu option from its pop up menu As a shortcut you can hold down the lt Shift gt key while you click a subpalette to drag it instead of opening it Both mnu files and VI library files are binary files that can contain one Controls palette and one Functions palette In addition both types of files contain an icon for the Controls and Functions palettes Each submenu that you create must be stored in a separate file When you select a view G looks for a directory in the menus directory It builds the
132. required to locate an element The data type of the array elements can be a cluster containing an assortment of types including arrays whose element type is a cluster and so on You cannot have an array of arrays Instead use a multidimensional array or an array of clusters of arrays Consider using arrays when you need to work with a collection of similar data Arrays are frequently helpful when you need to perform repetitive computations or I O functions Using arrays makes your application smaller faster and easier to develop because of the large number of array functions and VIs in G G Programming Reference Manual 14 4 National Instruments Corporation Chapter 14 Array and Cluster Controls and Indicators Creating Array Controls You create an array control by first selecting an array from Controls Array amp Cluster as shown in the following illustration err in err out esde code You create an array control or indicator by combining an array shell from the Array amp Cluster palette as shown in the preceding illustration with a valid element which can be a numeric Boolean string or cluster The element cannot be another array or a chart Also if the element is a graph then only the graph data types that contain clusters instead of arrays at the top level are valid Selecting an array from the Array amp Cluster palette places an array shell on the front panel as shown in the following illustration ind
133. resolution graphs e PostScript reproduces patterns and line styles more accurately G Programming Reference Manual B 8 National Instruments Corporation Appendix B Common Questions about G When I select PostScript printing why does my printout yield a pile up of printed text at the top of the page Printing translates the VI print data into PostScript PS format and sends it to the Windows printer driver as PostScript text If your printer driver does not work with PostScript printing the printout consists of the actual text of the PostScript file instead of a graphics image See the previous PostScript question for more information What should I do if the text on labels and front panel controls is clipped when the VI prints This occurs when the size of the font for the printer does not match the size of the font on the monitor e If your printer works with PostScript language use the PostScript printer driver for your printer to maintain higher quality printouts See the question above for more information on PostScript printing e Enlarge the labels and front panel controls so that when the text expands because of a font mismatch the text still fits in the control or label boundary e Find a font which is the same size on both the monitor and the printer Many printer drivers have font substitution algorithms to assist this process e Windows Use bitmap printing which makes the printout exactly match what you see
134. ring controls and indicators which are available from the Controls List amp Ring palette Chapter 14 Array and Cluster Controls and Indicators describes how to use arrays and clusters in the Controls Array amp Cluster pallette Chapter 15 Graph and Chart Controls and Indicators describes how to create and use the graph and chart indicators in the Controls Graph palette Block Diagram Programming G Programming Reference Manual Chapter 16 Introduction to the Block Diagram describes terminals and nodes two of the three elements you use to build a block diagram the third consists of wires xxii National Instruments Corporation Advanced G Topics About This Manual Chapter 17 Wiring the Block Diagram explains how to connect terminals on the block diagram by wiring them together Chapter 18 Structures describes how to use the For Loop While Loop Case Structure and Sequence Structure These structures are in the Functions Structures palette Chapter 19 Formula Nodes describes how to use the Formula Node to execute mathematical formulas on the block diagram The Formula Node is available from Functions Structures Chapter 20 Attribute Nodes describes how to use Attribute Nodes to set and read attributes of front panel controls programmatically Some useful attributes include display colors control visibility menu strings for a ring control graph or chart plot colors and graph cursors Chapter
135. rings appears as a flat black and white rectangle with drop shadow as shown in the following illustration You cannot color the dialog button or the dialog ring Because these controls change appearance you can create VIs with controls whose appearance is compatible with any of the computers that can run G Using these controls along with the checkmark and radio button Booleans simple numeric controls simple strings and the dialog fonts you can create a VI that adapts its appearance to match any computer you use the VI on By using the VI Setup options to hide the menu bar and scrollbars and control the window behavior you can create VIs that look like standard dialog boxes for that computer Customizing Controls Using Imported Graphics You can import graphics from other programs for use as background pictures as items in ring controls or as parts of other controls For more information on using graphics in these controls see Chapter 13 List and Ring Controls and Indicators and Chapter 22 Custom Controls and Type Definitions G Programming Reference Manual 8 10 National Instruments Corporation Chapter 8 Introduction to Front Panel Objects Before you can use a picture in G you have to load it into the G Clipboard There are one or two ways to do this depending on your platform as described below Windows If you can copy an image directly from a paint program to the Windows Clipboard and then switch to G G au
136. select a different pattern National Instruments Corporation 3 5 G Programming Reference Manual Chapter 3 Building SubVis Selecting and Modifying Terminal Patterns To select a different terminal pattern for your VI pop up on the connector and choose Patterns from the pop up menu UI Setup Edit Icon Show Icon Patterns Rotate 90 Degrees Flip Horizontal Flip Vertical Disconnect All Terminals iignagiiead f Pihis Farri Pig Gapraricad ing ES A solid border highlights the pattern currently associated with your icon as shown in the previous illustration To change the pattern choose a new one If you choose a new pattern any assignment of controls and indicators to the terminals on the old connector pane is lost If you want to change the spatial arrangement of the connector terminal patterns choose one of the following commands from the connector pane pop up menu Flip Horizontal Flip Vertical or Rotate 90 Degrees G disables these items if any terminal connections exist Assigning Terminals to Controls and Indicators After you decide which terminal pattern to use for your connector you must then assign front panel controls and indicators to the terminals Follow these steps 1 Click on a terminal of the connector The tool automatically changes to the Wiring tool The terminal turns black G Programming Reference Manual 3 6 National Instruments Corporation Chapter 3 Building SubVis Untitled
137. tasks execute The execution system maintains a queue of active tasks Assuming all tasks have the same priority the first task executes for a certain amount of time Then that task is put at the end of the queue and the next task executes for a time When a task completes execution the execution system removes it from the queue The execution system executes the first element of the queue by calling the generated code of the VI At some point the generated code of that VI checks with the execution system to see if it should assign another task to execute If not the code for the VI continues to execute Task Switching The currently executing task surrenders execution to other tasks in a number of situations described in the following list 1 The code of a VI occasionally checks to see how long it has been executing If the VI has not had a complete amount of time roughly 110 msecs then it continues to execute Otherwise it surrenders to the scheduler 2 Ifthe VI encounters a Wait Wait for Occurrence Dialog Box Function or Device I O function which are used by the GPIB and Serial Port VIs the VI surrenders to the scheduler G Programming Reference Manual 24 2 National Instruments Corporation Chapter 24 Understanding the G Execution System 3 When a VI surrenders to the scheduler the scheduler selects the highest priority VI on its queue to run next This can be the same VI that was running previously The schedul
138. the SPARC the bit left of the binary point is an implicit bit assumed always to be one which does not appear in the representation Strings Handles and Paths Arrays Because strings handles and paths have variable sizes the flattened form is preceded by a normalized long integer that records their length in bytes For paths this length is preceded by four characters PTHO For instance a string type with value ABC is flattened to 0000 0003 4142 43 The flattened format is similar to the format that the string takes in memory However handles and paths do not have a length value preceding them when they are stored in memory so this value comes from the actual size of the data in memory and prepends it when the data is flattened The data for a flattened array is preceded by normalized long integers that record the size in elements of each of the dimensions of the arrays National Instruments Corporation A 13 G Programming Reference Manual Appendix A Clusters Data Storage Formats The slowest varying dimension is first followed in order by the succeeding faster varying dimensions just as the dimension sizes are stored in memory The data follows immediately after these dimension sizes in the same order in which it is stored in memory Also this data is flattened if necessary The following is an example of a two dimensional array of six 8 bit integers 1 2 3 4 5 6 is stored as 0000 00
139. the following example y S u 2 xF logis Formula statements use a syntax similar to most text based programming languages for arithmetic expressions You can add comments by enclosing them inside a slash asterisk pair comment See general structs 1llb Equations vi for an example of a VI that uses a Formula Node The pop up menu on the border of the Formula Node contains options to add input and output variables as shown in the illustration that follows G Programming Reference Manual 19 2 National Instruments Corporation Chapter 19 Formula Nodes Show Description Add Input Add Output y S utZtu ogi Show Description Add Input Add Output y S utF u ogi Output variables are distinguished by a thicker border There is no limit to the number of variables or formulas in a Formula Node No two inputs and no two outputs can have the same name However an output can have the same name as an input Every variable used in the Formula Node for a calculation must be declared as either an input or an output Intermediate values that is outcomes of operations calculated after input s to the node but before the final output from the node must be declared as outputs However intermediate values do not need to be wired to nodes external to the National Instruments Corporation 19 3 G Programming Reference Manual Chapter 19 Formula Nodes Formula Node For example in the foll
140. to 23 5 G Programming Reference Manual calling functions that expect other data types 23 7 Configure option 23 3 creating parameter list 23 5 to 23 7 array data type 23 6 to 23 7 numeric data types 23 6 string data type 23 7 void data type 23 5 overview 23 2 calling code from other languages 23 1 to 23 13 See also applications managing Call Library Function Apple Event VIs 23 1 Code Interface Nodes 23 2 converting LabWindows CVI functions See LabWindows CVI Function Panel converter executing other applications from within VIs 23 1 to 23 2 carriage return backslash V code table 11 4 entering into string note 11 2 Limit to Single Line option 11 6 Case Insensitive suboption Keyboard Mode option 13 6 Case Sensitive suboption Keyboard Mode option 13 6 Case Structures adding subdiagrams 18 19 to 18 20 avoiding cycles in subVIs 3 13 commenting out sections of diagrams 4 31 deleting subdiagrams 18 20 to 18 21 editing 18 18 enumerated type wired to 3 11 example in examples 11b vi 18 14 icon for 18 2 18 13 moving between subdiagrams 18 18 to 18 19 out of range values note 18 14 overview 18 13 to 18 14 purpose and use 16 11 18 14 to 18 15 reordering subdiagrams 18 21 National Instruments Corporation subdiagram display window 18 13 wiring problems 18 22 to 18 26 Change Log File Binding option Data Logging menu 4 6 Change to Control option 8 3 14 20 17 13 Change to Custom
141. to a loop pass data before loop execution Outputs pass data out of a loop only after the loop completes all iterations You must place a terminal inside a loop when you want the loop to check the value of the terminal on each iteration For example when you place the terminal of a front panel Boolean control inside a While Loop and wire the terminal to the loop conditional terminal of the loop the loop checks the value of the terminal at the end of every iteration to determine whether it should iterate again You can stop this While Loop shown in the following figure by changing the value of the front panel control to FALSE G Programming Reference Manual 18 6 National Instruments Corporation Auto Indexing Chapter 18 Structures If you place the terminal of the Boolean control outside the While Loop as shown below you create an infinite loop If the control was TRUE at the start changing the value of the front panel control to FALSE does not stop the execution of this loop because the value is not propagated until the loop stops and the VI is re run If you inadvertently create an infinite loop you can stop it by aborting the VI Click on the abort button to stop execution For Loop and While Loop structures can index and accumulate arrays at their boundaries automatically These capabilities collectively are called auto indexing When you wire an array of any dimension from an external node to an input tunnel on the loop
142. to be made so the replace array element function safely modifies the data In this case the compiler schedules the execution of the functions in such a way that the function that wants to read the data executes first and the function that wants to modify the data executes last This way the Replace Array Element function reuses the incoming array buffer without generating a duplicate array If the ordering of the nodes is important you should G Programming Reference Manual 26 16 National Instruments Corporation Chapter 26 Performance Issues make the ordering explicit by using either a sequence or an output of one node for the input of another In practice the analysis of diagrams by the compiler is not perfect In some cases the compiler might not be able to determine the optimal method for reusing diagram memory Monitoring Memory Usage There are a couple of methods for determining memory usage If you select Help About LabVIEW if you are a LabVIEW user or Help About Bridge VIEW if you are a Bridge VIEW user you see statistics that summarize the total amount of memory used by your application This memory includes memory for VIs as well as memory that the application uses You can check this amount before and after execution of a set of VIs to obtain a rough idea of how much memory the VIs are using You can obtain a view of the dynamic usage of memory by your VIs with the Performance Profiler It keeps statistic
143. to the other Only the displayed representation of certain characters changes The backslash mode is very useful for debugging programs and for sending nonprintable characters to instruments serial ports and other devices Password Display Option With the Password Display option the string control displays an for each character entered into it When you read the data of the string from the block diagram however you read the actual data that the user entered If you try to copy data from the control only the characters are copied Hex Display Option Use the Hex Display option to display the string as hex characters rather than alphanumeric characters National Instruments Corporation 11 5 G Programming Reference Manual Chapter 11 String Controls and Indicators Limit to Single Line Option The Limit to Single Line option prevents you from entering a carriage return into a string while typing into it Tables A table is a 2D array of strings The following illustration is an example of a table with all its features shown call indicated by index values column headings vertical index ae SE index ab vertical w scrollbar headings horizontal scrollbar A table has row and column headings which are separated from the data by a thin open border space You enter headings when you place the table on the front panel and you can change them using the Operating tool or Labeling tool You c
144. to the other panel or diagram to which you want to copy it For more information see the Dragging and Dropping VIs Pictures and Text in G section in this chapter Instead of duplicating data types for existing front panel controls you can copy clone or drag and drop them to any diagram to make a corresponding constant In the same way you can drag user defined constants from the block diagram to the front panel to create controls Deleting Objects To delete an object select the object and choose Edit Clear or press the lt Backspace gt Windows and HP UX key or the lt Delete gt key Macintosh and Sun You only can delete block diagram terminals by deleting the corresponding front panel controls or indicators Although you can delete most objects you cannot delete parts of a control or indicator such as labels or digital displays However you can hide these components by deselecting Show Label or Show Digital Display from the pop up menu of the object If you delete a structure such as a While Loop the contents are deleted as well If you want to delete only the structure itself but preserve its contents pop up on the edge of the structure and select Remove While Loop or other structure name You delete the structure but not its contents and automatically reconnect any wires that crossed the border of the structure National Instruments Corporation 2 13 G Programming Reference Manual Chapter 2 Building Vis Labe
145. top level Controls and Functions palettes from the root mnu file within that directory The top level palettes then link to other mnu or VI library files for each subpalette within the palette If you link in a directory you initiate a search to check if the directory contains a dir mnu file If so the directory uses that mnu file as the subpalette for the directory Otherwise your application creates a dir mnu file based on the contents of the directory For each VI or control an entry is created For each subdirectory mnu file or VI library your application creates a subpalette G automatically updates the palettes within a VI library as you add files to or remove files from the VI library You have the option to set a mnu file to update based on the contents of a directory To change this setting select Synchronize with Directory from the pop up menu of the subpalette icon Although it is a good idea to have the mnu file in the same directory with which it is synchronized you actually can select any directory In addition to reflecting a specific directory you can have additional VIs or controls from other directories in the same palette You also can remove VIs from the palette by selecting Delete Item from the pop up menu National Instruments Corporation 7 29 G Programming Reference Manual Chapter Introduction to Front Panel Objects This chapter introduces the front panel and its two components controls and
146. understand data formats and storage in G LabWindows CVI Function Panel Converter Note This feature is not available on the Macintosh The LabWindows CVI Function Panel converter automates the process of converting instrument drivers written in LabWindows CVI so they National Instruments Corporation 23 7 G Programming Reference Manual Chapter 23 Calling Code from Other Languages can be used in G A LabWindows CVI instrument driver consists of a C source and header files a Dynamic Link Library DLL Windows or shared library UNIX containing the compiled code and a LabWindows CVI specific file called a Function Panel FP file Function Panel files are used in LabWindows CVI so that users can specify arguments and return values when editing a C function call statement by filling in values in a pop up window The LabWindows CVI Function Panel converter converts each function into a VI using the information in the CVI FP file to determine the type data representation and placement of controls on the VI front panels Each generated VI uses a Call Library Function node on its block diagram to call the appropriate C routine in the appropriate driver library Although many instrument drivers are written completely on the diagram without calling library functions the LabWindows CVI Function Panel converter has advantages in some cases For instruments where a G driver is not available this tool makes it relatively easy to take
147. up the Print Documentation dialog box from which you can choose the portion of the VI you want to print For more information on this dialog box see the Selecting Print Options section of Chapter 5 Printing VIs Hierarchy Node Mouse Click Sequences Mouse click sequences are available for selecting nodes for copying or dragging nodes and for shortcuts to certain pop up menu options Where applicable the sequences are performed with the Positioning tool selected The shortcut mouse clicks are as follows For a more complete description of options available in the pop up menu see the section Hierarchy Node Pop Up Menu of this chapter National Instruments Corporation Clicking on the red arrow button executes the Show Immediate SubVIs action lt Shift gt clicking on the red or black arrow button executes the Show All SubVIs action Pressing lt Ctrl click gt Windows lt option click gt Macintosh lt meta click gt Sun and lt Alt click gt HP UX on the node executes the Show VI Hierarchy action Double clicking on the node executes the Open Front Panel action Single clicking on the node selects it for dragging to a block diagram or copying to the Clipboard to use as a subVI 3 21 G Programming Reference Manual Chapter 3 Building SubVIs e By lt Shift gt clicking on and holding the mouse button down while selecting you can select multiple nodes for copying to other block diagrams or front panels
148. use Suspend range checking if memory and speed are a major concern Remember if you have set a subVI to display its front panel when called using VI Setup or SubVI Setup the panel is loaded into memory when the subVI is called If you have set the Close if Originally Closed option the panel is removed from memory when the subVI finishes execution SubVis Can Reuse Data Memory In general a subVI can use data buffers from its caller as easily as if the diagrams of the subVI were duplicated at the top level For most subVIs you do not use more memory if you convert a section of your diagram into a subVI For VIs with special display requirements as described in the previous section there might be some additional memory usage for front panels and controls Local Variables Cannot Reuse Data Memory When you create subVIs you create a connector pane that describes how data is passed to and from the subVI The data buffers that come from terminals that are connected to a connector pane can reuse data buffers from calling VIs Local variables cannot do this Instead when G Programming Reference Manual 26 20 National Instruments Corporation Chapter 26 Performance Issues you read from a local variable you create a new buffer for the data from its associated control If you use local variables to transfer large amounts of data from one place on the diagram to another you generally use more memory and consequently have slower exec
149. value associated with the marker position You can change the outer two markers the scale limits and you can change any inner markers from even spacing to place them anywhere you want National Instruments Corporation 9 15 G Programming Reference Manual Chapter 9 Numeric Controls and Indicators Changing Scale Limits The outer two markers are the scale limits They are not required to coincide with the range limits but they can be a subset of the range of the control or indicator For example the default range of a 16 bit signed integer control or indicator is 32 768 to 32 767 However you can set the data range to be 1 000 to 1 000 and then set the scale limits to be 0 and 500 representation limits You can change the minimum maximum and increment of a scale interactively in five ways using either the Operating tool or the Labeling tool If you want to change a scale programmatically use the Attribute Node See Chapter 20 Attribute Nodes for more information on changing a scale programmatically using the Attribute Node e If you type a new maximum value into its display the minimum stays the same and G recalculates the increment automatically e If you type a new minimum value into its display the maximum stays the same and G recalculates the increment automatically e If you type the current minimum value into the maximum display G flips the scale so that what was formerly the minimum is
150. video driver where it is three pixels smaller than the default Overlapping Labels When you move a VI to a new platform controls and labels might change size depending on if the fonts are smaller or larger G tries to keep labels from overlapping their owners by moving them away from the owning control Also every label and constant has a default attribute called Size to Text When you first create a label or constant this attribute is set so the bounds of the object resize as necessary to display all of the enclosed text If you ever manually resize the object the application turns off this attribute the item in the pop up menu is no longer checked With Size to Text turned off the bounds of the object stay constant and the application clips or crops the enclosed text as necessary If you do not want the application to clip text when you move between systems or platforms leave this attribute on for labels and constants Most Sun and HP monitors are much larger and have a higher resolution than PC and Macintosh monitors If you are a Sun or an HP UX user do not make your front panels very large if you want them to port well For best results avoid overlapping controls and leave extra space If a label even partially overlaps another object and the font is enlarged it might end up overlapping the control Picture Differences The most basic type of picture contains a bitmap a series of values specifying the color of each
151. want rows to appear as rows use the Transpose Array option from the chart pop up menu Intensity Graph Options The intensity graph works much like the intensity chart except it does not have the chart update modes Because each update replaces the National Instruments Corporation 15 29 G Programming Reference Manual Chapter 15 Graph Cursors Graph and Chart Controls and Indicators previous data it does not have a scrollbar and it does not have history options The intensity graph can have cursors like other graphs Each cursor displays the X Y and Z values for a specified point on the graph See the Graph Cursors section of this chapter for more information on manipulating the cursors on the graph You set the color mapping in the same way that you set it for the intensity chart For each graph you can display a Cursor palette that you use to put cursors on the graph You can label the cursor on the plot You also can use a cursor as a marker When you use a cursor as a marker you lock the cursor to a data plot so that the cursor follows the data Cursors can be set and read programmatically using the Attribute Node You can set a cursor to lock onto a plot and you can move multiple cursors at the same time There is no limit to the number of cursors that a graph can have G Programming Reference Manual 15 30 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators Following ar
152. want to execute a VI with a section of the block diagram disabled The easiest way to do this is to enclose the section of diagram that you want disabled in a Case Structure with a constant Boolean wired to the selector Put the diagram you want to disable in the frame of the Case Structure that does not execute If the Case Structure produces any values enter a value for the output tunnels National Instruments Corporation 4 31 G Programming Reference Manual Chapter Printing Vis This chapter discusses printing issues in G Printing in G There are three primary ways to print VIs in G e You can use the Print Window option to make a quick printout of the contents of the current window e You can make a more comprehensive printout of a VI including information about the front panel block diagram subVIs controls VI history and so on by selecting the Print Documentation option e You can use the G programmatic printing feature to make VIs that can print under the control of your application In addition you can use the Serial Port VIs to send text to the printer if you have a printer connected to your serial port doing so generally requires some knowledge of the command language of the printer In Windows and UNIX another option for printing is to use the System Exec VI located in Functions Communication On the Macintosh you can use the AESend Print Document VI located in Functions Communication App
153. warning in such cases you must decide whether to continue or cancel Case Structures Containing Attribute Nodes Locals or Front Panel Terminals Try to avoid including a Case Structure containing an Attribute Node front panel terminal or local variable to which a value is written In such cases when the subVI is executed a specific value always is written to the object because you wire it to the subVI Although it exists in the original block diagram a value can be written only when either the TRUE or FALSE part of the Case Structure executes This can change the functionality of the caller VI G displays a warning in such cases you must decide whether to continue If you continue you first must edit the subVI to supply a value in all cases National Instruments Corporation 3 13 G Programming Reference Manual Chapter 3 Building SubVis Consider the following illustration as a simple example The Case Structure is selected for conversion into a subVI The front panel terminal Output is left out in the original diagram and connected to the subVI through a connector as shown in the following illustration In the original block diagram G wrote a value to Output only when the FALSE part of the case executed However when the selection turns into a subVI G always writes a value to Output regardless of whether the TRUE or FALSE part of the case was executed within the subVI You need to edit the subVI to supply data fo
154. while G uses a graphical programming language to create programs in block diagram form Components of a VI G is a general purpose programming system but it also includes libraries of functions and development tools designed specifically for data acquisition and instrument control G programs are called virtual instruments VIs because their appearance and operation can imitate actual instruments However VIs are similar to the functions of conventional programming languages A VI consists of an interactive user interface a dataflow diagram that serves as the source code and icon connections that set up the VI so that National Instruments Corporation 1 1 G Programming Reference Manual Chapter 1 Introduction to G Programming i Note it can be called from higher level VIs More specifically VIs are structured as follows e The interactive user interface of a VI is called the front panel because it simulates the panel of a physical instrument The front panel can contain knobs pushbuttons graphs and other controls and indicators You enter data using a mouse and keyboard and then view the results on the computer screen e The VI receives instructions from a block diagram which you construct in G The block diagram is a pictorial solution to a programming problem The block diagram is also the source code for the VI e VIs are hierarchical and modular You can use them as top level programs or as subprograms within
155. you move the increment and decrement arrows so they are side by side at the bottom of the ring the ring continues to make them become taller when it increases and you produce some strange results G Programming Reference Manual 22 18 National Instruments Corporation Chapter 22 Custom Controls and Type Definitions e Custom controls often look correct but occasionally behave oddly If you like the control the way you have made it but are not pleased with its irregular editing behavior read about strict type definitions in the next section Type Definitions to learn how editing can be restricted Type Definitions A type definition is a master copy of a control You use the Control Editor to create the master copy or type definition Type definitions are useful when you use the same kind of controlin many VIs You can save the control as a type definition and use that type definition in all your VIs Then if you need to change that control you can update the single type definition file instead of updating the control in every VI that uses it General Type Definition Matching Data Types A type definition forces the control data type to be the same everywhere it is used Use a type definition when you want to use a control of the same data type in many places and when you might want to change that data type automatically everywhere it is used For example suppose you make a type definition from a double precision digital cont
156. your application displays the object it considers to be in front If you put the structure completely over another object and your application makes it the frontmost object it displays a thick shadow to warn you that the object is below not inside the structure Otherwise the structure is hidden completely by the object For information on which objects your application selects as frontmost see the section Positioning Objects in Chapter 2 Building VIs Both situations are shown in the following illustration G Programming Reference Manual 18 4 National Instruments Corporation Chapter 18 Structures Placing and Sizing Structures on the Block Diagram When you select a structure from Functions Structures and prepare to put it on your diagram you see a small icon of the structure in place of your cursor This icon is ready to be placed on your block diagram You either can click on and release your mouse button to drop a small default size structure on the diagram or you can click on the diagram while holding down the mouse and drag the structure to the size you want An example is shown in the following illustration You also can National Instruments Corporation 18 5 G Programming Reference Manual Chapter 18 Structures size the structure after you have dropped it on the diagram by clicking on any corner with the Resizing cursor and dragging OoOoOooo0go od o0000 0 0 0 0O Placing Terminals inside Loops Inputs
157. your front panel except to change its name description or default value G Programming Reference Manual 22 20 National Instruments Corporation Chapter 22 Custom Controls and Type Definitions You can tell that a control is a type definition when you see the type definition options in its pop up menu as shown in the following illustration You can recognize a strict type definition on your front panel because you cannot edit it and most of its pop up menu options are missing vouaio from Tupe pef lt Huto Update Type Def Disconnect from Type Def For each type definition that you use on a front panel the VI keeps a connection to the file or VI library in which it is saved You can see this connection in action if you place a type definition on a front panel and then select it and choose Edit Edit Control The Control Editor that opens is the type definition you saved with the name you gave it instead of the generic Control N Updating Type Definitions Your G development environment ensures that the data type is the same everywhere a type definition is used and that everything about a strict type definition is the same everywhere it is used You can update any general type definitions or strict type definitions on your front panel that are incorrect automatically replacing the one on your front panel with an exact copy of the one saved in the file or VI library If you have edited an instance of a type definition on
158. 02 0000 0003 0102 0304 0506 The following is an example of a flattened one dimensional array of Boolean variables T F T T is stored as 0000 0004 BOOO The binary encoding of B is 1011 Boolean arrays are stored as packed bits unlike other arrays A flattened cluster is the concatenation in cluster order of the flattened data of its elements So for example a flattened cluster of a word integer of value 4 decimal and a long integer of value 12 is 0004 0000 000C A flattened cluster of a string ABC and a word integer of value 4 is 0000 0003 4142 4300 04 A flattened cluster of a word integer of value 7 a cluster of a word integer of value 8 and a word integer of value 9 is 0007 0008 0009 To unflatten this data you just use the reverse process The flattened form of a piece of data does not encode the type of the data you need the type descriptor for that The Unflatten From String function requires you to wire a data type as an input so that the function can decode the string properly G Programming Reference Manual A 14 National Instruments Corporation Appendix Common Questions about G This appendix answers some of the questions commonly asked by G users Charts and Graphs How do wire data to a chart or graph Show the Help window and move the Wiring tool across a graph terminal in the block diagram to see a brief description of how to wire basic graph types There are excellent exam
159. 1 2 Click on the front panel control or indicator you want to assign to the selected terminal A marquee frames the selected control 3 Position the cursor in an open area of the front panel and click on it The marquee disappears and the selected terminal turns to gray indicating that the terminal has been assigned At Bats Batting Average National Instruments Corporation 3 7 G Programming Reference Manual Chapter 3 Building SubVis iPr Note If the connector terminal turns white then a connection was not made Repeat steps 1 through 3 until the connector terminal turns gray Although you use the Wiring tool to assign terminals on the connector to front panel controls and indicators no wires are drawn between the connector and these controls and indicators 4 Repeat steps 1 and 2 for each control and indicator you want to connect You also can select the control or indicator first and then select the terminal You can choose a pattern with more terminals than you need You can leave some extra terminals unconnected if you anticipate making changes to the VI in the future that require a new input or output Having the extra connections available means that the new input or output does not affect other VIs that already are using this VI as a subVI Unassigned terminals do not affect the operation of the VI You also can have more front panel controls than terminals The connector pane has at most 28 terminals If
160. 10 imported graphics for customizing controls 8 10 to 8 11 Key Navigation option for controls 8 5 to 8 8 Panel Order option 8 8 to 8 9 replacing controls 8 4 to 8 5 color settings 7 13 Controls palette 1 3 creating pop up panels See pop up panels creating data logging 4 5 to 4 7 help information 1 7 illustration 1 3 labels 2 3 G Programming Reference Manual l 32 memory usage rules 26 19 to 26 20 printing Front Panel option 5 5 resizing work space 2 24 switching to block diagram 1 3 terminals avoiding cycles in subVIs 3 13 created automatically 2 3 to 2 4 Front Panel Control and Indicator pop up menu 8 2 to 8 4 Change to Control 8 3 Change to Indicator 8 3 Create Attribute Node 8 3 Data Operations submenu 8 3 Find Terminal 8 3 illustration 8 2 Key Navigation 8 5 to 8 8 Replace 8 4 to 8 5 Show submenu 8 3 Front Panel option Custom Print Settings dialog box 5 5 Front Panel Preferences dialog box 7 9 to 7 11 Blink speed 7 10 End text entry with Return key same as Enter key 7 10 illustration 7 9 Open the control editor with double click 7 9 Override system default function key settings 7 10 Support numeric keypad on Sun keyboards 7 10 Use localized decimal point 7 10 Use smooth updates during drawing 7 10 Use transparent name labels 7 10 FTP support C 1 Full VI Path in Label option 3 19 function key defaults overriding 7 10 functions 16 8 to 16 11 default labels 2 15 defi
161. 11 to 2 12 coloring objects 2 24 to 2 26 creating object descriptions 2 26 to 2 27 creating VI descriptions 2 26 to 2 27 deleting objects 2 13 distributing objects 2 12 dragging and dropping VIs pictures and text 2 8 to 2 9 duplicating objects 2 12 to 2 13 labeling objects 2 14 to 2 22 free labels 2 14 to 2 16 text characteristics 2 16 to 2 22 positioning objects 2 9 to 2 11 resizing objects 2 23 to 2 24 front panel and block diagram work space 2 24 labels 2 23 to 2 24 selecting objects 2 7 to 2 8 switching from run mode to edit mode note 6 6 while running VIs 4 2 to 4 4 control pop up menu options 4 2 to 4 3 object pop up menu options 4 3 to 4 4 efficient data structures See performance issues electronic support services C 1 to C 2 e mail support C 2 Empty Array command 14 13 empty arrays 14 12 Enable Database Access option 4 7 4 8 Enable Indexing option 18 8 Enable Log Print at Completion option 6 6 National Instruments Corporation Index End Selection option 14 14 14 15 14 16 15 33 Enter button changing cluster order 14 22 changing numeric control and indicator values 9 2 data logging on front panel 4 6 Enter gt key data tables 11 7 entering linefeed into string note 11 2 finding next matching node 3 23 Key Navigation option associations 8 6 label names 2 3 2 14 setting Enter key same as Return key 7 10 string controls and indicators 11 1 enumerated constants 16
162. 12 data types examples A 10 to A 11 non numeric table A 10 scalar numeric table A 8 to A 9 storage of physical quantities note A 11 definition A 7 generic format A 7 overview A 7 to A 8 U Unbundle By Name function accessing cluster elements 22 22 disassembling cluster elements 14 30 to 14 32 Unbundle function 14 29 to 14 30 unbundling cluster elements 14 19 National Instruments Corporation undefined data 4 17 to 4 18 units 9 26 to 9 35 entering units 9 31 to 9 33 polymorphic units 9 35 pop up menu 9 27 showing unit label 9 26 to 9 27 strict type checking 9 33 to 9 34 types additional units in use with SI units table 9 29 to 9 30 base units table 9 28 CGS units table 9 30 derived units with special names table 9 28 to 9 29 other units table 9 30 to 9 31 universal constants character 16 7 definition 16 3 numeric 16 7 Unopened SubVIs 4 16 unsigned integer representation See signed and unsigned integer representation Update from Type Def option 22 22 Update Mode option 15 25 Use History Defaults In Preferences Dialog option 6 3 User Libraries subpalette 7 25 User Name option Edit menu 7 19 user defined constants 16 3 to 16 7 availability in palettes 16 3 to 16 4 color box 16 6 creating 16 3 to 16 4 enumerated 16 6 error ring 16 6 to 16 7 incrementing and decrementing 16 5 list box symbol ring 16 6 numeric 16 4 numeric constant pop up menu 16 5 path
163. 16 7 ring 16 6 setting values 16 4 string 16 4 string constant pop up menu 16 5 National Instruments Corporation Index user 1lib adding VIs and controls 7 25 Using as a SubVi format option 5 3 Using the Panel format option 5 3 V Valid Path option 12 2 Vertical Centers alignment 2 12 Vertical Hierarchy option 3 18 VI descriptions creating 2 27 VI Hierarchy option 5 6 VI history See also History Preferences dialog box adding entries 6 4 7 18 printing 5 6 VI History option 5 6 VI History window 25 6 to 25 9 example 25 6 printing history information 25 9 recording comments note 25 6 related VI Setup and Preferences dialog options 25 9 resetting history information 25 8 revision numbers 25 7 to 25 8 VI libraries LLBs 2 29 to 2 30 arranging files in VI libraries 25 1 to 25 2 avoiding saving VIs in vi 1ib directory note 2 29 creating 2 30 editing contents of libraries 2 30 including in Hierarchy window 3 18 3 19 reasons for saving VIs as libraries 2 29 saving VIs in existing VI libraries 2 30 setting library directories 7 3 to 7 4 Top Level setting 2 30 VI search path setting 7 5 to 7 6 G Programming Reference Manual Index VI Setup dialog box accessing 6 1 documentation options 6 3 to 6 4 Add an entry every time this VI is saved 6 4 Help Path box 6 4 Help Tag box 6 4 illustration 6 3 managing applications 25 9 Prompt for comment when this VI is closed 6 4
164. 2 Remove Item option 13 9 Remove While option 2 13 removing See also deleting paths using Remove button 7 6 structures without deleting contents 18 26 reordering subdiagrams 18 21 Replace option control and indicator pop up menu 8 4 to 8 5 Increment node pop up menu 16 12 replacing block diagram objects 16 12 controls 8 4 to 8 5 National Instruments Corporation Index representation of numeric values available types of representation 9 4 to 9 5 constants 16 7 selecting 9 4 to 9 5 Representation option 9 4 to 9 5 Representation palette 13 11 resetting history information 25 8 resizing 2 23 to 2 24 arrays 14 14 canceling resizing operation 2 23 clusters 14 22 to 14 23 columns 11 6 to 11 7 front panel and block diagram work space 2 24 labels 2 23 to 2 24 rows 11 6 to 11 7 tables 11 6 to 11 7 Resizing cursor 2 23 resizing handles 2 23 Resizing tool Array Resizing tool 14 9 Usual Resizing symbol 14 10 Retrieve option 4 6 retrieving data programmatically 4 7 to 4 9 accessing databases 4 7 to 4 9 halo terminals for accessing data 4 7 4 8 using file I O functions 4 9 Return to caller button 4 30 lt Return gt key data tables 11 7 entering linefeed into string note 11 2 finding next matching node 3 23 Key Navigation option associations 8 6 label names 2 3 2 14 setting Enter key same as Return key 7 10 string controls and indicators 11 1 Reverse Ticks option 22 15 Revert o
165. 2 Style option Font ring 2 17 Scale pop up menu 9 15 subdiagram display window Case and Sequence Structures 18 13 diagram identifier 18 13 subdiagrams adding 18 19 to 18 20 definition 18 2 deleting 18 20 to 18 21 moving between 18 18 to 18 19 reordering 18 21 subpalettes creating 7 27 to 7 29 moving 7 29 SubVI From Selection option 3 10 SubVI Node Setup dialog box 6 6 illustration 6 6 options 6 6 SubVI Node Setup option 4 29 G Programming Reference Manual I 52 subVIs analogous to subroutines in C 3 1 building See building subVIs calling two distinct subVIs with same name B 11 connections to calling VIs in Hierarchy window 3 16 to 3 17 icons representing 1 6 inability to edit descriptions from calling VI diagram note 2 27 labels on block diagram note 2 16 memory usage 26 20 performance considerations 26 9 printing list of subVIs 5 6 replacing subVI with same name B 11 reusing data memory 26 20 showing subVI name when dropped on block diagram 7 11 Sun numeric keypad supporting 7 10 Surround Panel with Border option 5 8 Suspend When Called option Operate menu 4 29 SubVI Node Setup dialog box 6 6 VI Setup dialog box 6 2 suspending execution 4 29 to 4 30 during debugging 4 29 options 4 29 recognizing automatic suspension 4 29 to 4 30 Return to caller button 4 30 Run button 4 30 Skip to beginning button 4 30 using toolbar buttons during suspension 4 30 viewing Hierarchy wind
166. 2 vi with this subVI vi If the connector pane is exactly the same it will probably link fine but the behavior may be very peculiar If the connector pane is different the user receives a bad linkage error Solution Always give subVIs unique names When loading and executing multiple Vis how is the priority of execution assigned to the Vis You can use the G execution system to execute multiple VIs or subdiagrams in parallel and to assign priorities to VIs Priorities range from 0 low to 3 high with an additional highest level of subroutine At any one time only one section of code executes other sections wait on an execution queue If the code does not complete in a given time period G puts it back on the queue and the frontmost queue element starts running In this fashion execution passes round robin between VIs or subdiagrams You can alter the priority of a VI through the dialog box in VI Setup A VI with high priority automatically bumps its subVIs to the same level of priority For example if main vi has priority 3 high and subVI vi has priority 1 not as high then when main vi calls subVI vi subVI vi has priority 3 With priorities the G internal execution queue has multiple entry points The queue is always ordered via priority as in this example sss322211111 If a new item with priority 3 is placed on the queue then the queue would look like the following sss3322211111 The new 3 item is pla
167. 21 Global and Local Variables describes how to define and use global and local variables You can use global variables to access a particular set of values easily Local variables serve a similar purpose within a single VI Chapter 22 Custom Controls and Type Definitions introduces custom controls and type definitions Chapter 23 Calling Code from Other Languages explains various methods of calling code written in other languages Chapter 24 Understanding the G Execution System explains VI multitasking and execution Chapter 25 Managing Your Applications contains information about managing your files in G Chapter 26 Performance Issues is divided into three sections The first section discusses the Performance Profiler a feature that shows you data about execution time of your VIs The second section discusses factors that affect run time speed The third section discusses factors that affect memory usage Chapter 27 Portability Issues discusses issues related to transporting VIs between platforms Appendices Glossary and Index National Instruments Corporation Appendix A Data Storage Formats discusses the formats in which you can save data xxiii G Programming Reference Manual About This Manual e Appendix B Common Questions about G answers some of the questions commonly asked by G users e Appendix C Customer Communication contains forms to help you gather the information necessary to help Nationa
168. 28 National Instruments Corporation Chapter 3 Building SubVis e Stop Appears in place of the Find button during a search If there is a long search through many VIs the Search Results window updates search results as they are found and shows the status of the search You use the Stop button to interrupt the search If you delete an object or VI and it is part of a search result then the item entry of that result is disabled Notice however that modifying text does not update the search results Therefore you might highlight a text search result that no longer matches the search criteria In that case perform another find to update the search results Finding Next and Previous Search Items Select Project Find Next to highlight the next and previous results in the search list For hidden text all objects needed to display the text are made temporarily visible as grayed out objects and the text is selected when you click on the mouse or press a key the objects are hidden again Find Pop Up Menu for Global and Local Variables and Attribute Nodes A Find pop up menu item is available on controls front panel controls and indicators global variables locals variables and Attribute Nodes You can pop up on a local variable or Attribute Node to find its corresponding control front panel terminal or other local variables and Attribute Nodes Conversely controls and front panel controls and indicators have pop up menus to find
169. 3 23 G Programming Reference Manual Chapter 3 Building SubVis Find Dialog Box To bring up the Find dialog box select Project Find or press lt Ctrl f gt Windows lt command f gt Macintosh lt met a f gt Sun or lt Alt f gt HP UX As a shortcut you can select a piece of text or an object before accessing the dialog box The dialog box appears with the text or object preselected for the search Finding Vis and Other Objects To search for VIs or other objects click on the Objects button in the Find dialog box Find Search for Objects K Text q Cancel Select Object Search Scope lt All UIs in Memory vj i tpfpgfha i O Search in Hierarchy window O Search Vis in viib To select the object you want to search for click on the button after the words Select Object The Select Objects menu appears G Programming Reference Manual 3 24 National Instruments Corporation Chapter 3 Building SubVIs Find Search for Objects Ch Text Select Object f Functions E Ils Type Defs Globals Objects in vi lib Others lt All UIs in Memory L Search in Hierarchy Winda Vis by Name L Search is in vilib The options available in this menu are as follows National Instruments Corporation Functions Brings up the Functions palette so you can select built in functions VIs or any objects that you have customized to appear in the Functions palette Vi
170. 5 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators With the Show submenu of the chart pop up menu you can show or hide optional digital display s and a scrollbar The Digital Display option displays the latest value being plotted The last value passed to the chart from the diagram is the latest new value for the chart There is one digital display per plot You can view past values contained in the buffer by scrolling the x axis to a range of previously plotted values using the scrollbar or by changing the x scale range to view old data The chart has a limit to the amount of data it can remember to avoid running out of memory When the chart reaches that limit the oldest point s are thrown away to make room for new data The default size of this buffer is 1 024 points You can change the length of this buffer using the Chart History Length option from the chart pop up menu Chart Update Modes To change the way the chart behaves when new data is added to the display use the Update Mode option from the Data Operations submenu of the pop up menu of the chart shown in the following illustration Change to Control Find Terminal Show Data Operations Reinitialize to Default Create Make Current Value Default Key Navigation Cut Data Replace Copy Data Paste Data x Scale Description Y Scale Online Help Transpose Array Stack Plots Clear Chart Chart History Length AutoScale x AutoScal
171. 6 enumerated data types changing programmatically B 15 enumerated type controls 13 10 to 13 12 compared with ring controls 13 11 illustration 13 11 purpose and use 13 11 to 13 12 error messages and crashes questions about B 4 to B 5 error ring constant 16 6 to 16 7 errors Formula Node table 19 9 to 19 10 errors for broken VIs Error List window accessing 4 10 illustration 4 10 possible errors table 4 11 to 4 14 showing warnings 7 12 executing VIs 4 1 to 4 9 data logging on front panel 4 5 to 4 7 loading questions about B 10 to B 12 retrieving data programmatically 4 7 to 4 9 accessing databases 4 7 to 4 9 using file I O functions 4 9 running VIs 4 1 to 4 4 buttons for running 4 1 editing while running 4 2 to 4 4 A G Programming Reference Manual Index loading and running dynamically B 10 multiple VIs 4 2 running repeatedly 4 5 stopping VIs 4 4 execution highlighting See highlighting execution execution options VI Setup dialog box 6 2 to 6 3 Close Afterwards if Originally Closed 6 2 illustration 6 2 Run When Opened 6 2 Show Front Panel When Called option 6 2 Show Front Panel When Loaded option 6 2 Suspend When Called 6 2 expandable functions 16 10 extended numeric data storage format A 1 to A 2 extended precision representation EXT 9 4 F fax and telephone support C 2 FaxBack support C 2 File Convert CVI FP File option 23 8 file dialog boxes native 7 21 to 7
172. 7 to 4 18 understanding warnings 4 18 single stepping through VIs 4 18 to 4 20 example 4 19 to 4 20 executing VIs 4 18 to 4 19 Pause button 4 18 Step Into button 4 20 Step Out button 4 20 Step Over button 4 18 4 20 using step buttons 4 20 decimal separator selecting 7 10 Decorations palette 5 8 22 17 default directories setting 7 3 to 7 5 default timer using 7 7 to 7 8 Delete button front panel data logging 4 6 Delete Marker option 9 17 Delete this Parameter option 23 5 lt Delete gt key deleting objects 2 13 deleting wires 17 6 National Instruments Corporation Index deleting See also removing data records 4 6 graph cursors 15 33 objects 2 13 removing structures without deleting contents 18 26 structures while preserving contents 2 13 subdiagrams 18 20 to 18 21 terminal connections 3 9 to 3 10 wires 17 6 to 17 10 Description option Data Operations menu 2 26 descriptions See also documentation options VI Setup dialog box creating objects 2 26 to 2 27 VIs 2 27 inability to edit subVI descriptions from calling VI diagram note 2 27 destination terminals 16 1 Development Distribution option 25 4 Device RefNum 12 4 diagram identifier subdiagram display window 18 13 Diagram window 1 4 dialog box controls customizing 8 9 to 8 10 Dialog Box option VI Setup dialog box 6 5 Dialog font 2 18 digital controls and indicators 9 2 to 9 11 changing representation of numeric v
173. 8 2 Replace 8 4 to 8 5 Show submenu 8 3 imported graphics for customizing 8 10 to 8 11 owned labels 2 15 panel order 8 8 to 8 9 printing Controls option 5 5 to 5 6 Descriptions option 5 6 Include Data Type Information option 5 6 replacing controls 8 4 to 8 5 terminals 16 2 to 16 3 symbols table 16 2 to 16 3 Controls option Custom Print Settings dialog box 5 5 to 5 6 Controls palette control flow execution Sequence Structures 18 16 Controls and Functions palettes customizing 7 25 to 7 29 National Instruments Corporation adding VIs and controls to user 1iband instr lib 7 25 creating subpalettes 7 27 to 7 29 installing and changing views 7 26 moving subpalettes 7 29 Palettes editor 7 26 to 7 29 views 7 29 accessing cluster shell 14 20 adding custom controls 22 1 22 5 controls available on palette 8 1 to 8 2 illustration 1 3 8 1 pop up palette 2 3 selecting objects 2 1 to 2 3 temporary copy 2 3 Conversion Options dialog box See LabWindows CVI Function Panel converter Convert CVI FP File option 23 8 G Programming Reference Manual Index cooperative multitasking See multitasking Copy Data option Data Operations menu 11 8 Probe tool 4 25 Copy option Edit menu 2 12 Copy to Clipboard option cosmetic parts pop up menu 22 10 copying duplicating objects 2 12 to 2 13 cosmetic parts 22 9 to 22 14 adding to custom controls 22 17 to 22 18 definition 22 9 independ
174. 8 to 2 047 you scale this data to its appropriate voltage values of 10 to 10 by specifying an additive offset of 2 038 and a scaling factor of 4 096 20 204 8 Format amp Precision At the top of the dialog box is a pop up menu from which you can decide if the X or Y scale is formatted for numerics or for time and date If you select Numeric formatting you can choose if the notation is floating point scientific engineering or relative time in seconds if the notation is decimal unsigned decimal hexadecimal octal and binary and you can select the precision that is how many digits are displayed to the right of the decimal point from 0 through 20 The precision you select affects only the display of the value the internal accuracy still depends on the representation Examples are shown in the dialog box as you select each combination of options If you select Time amp Date formatting the dialog box changes as shown in the following illustration H Scale Formatting Format and Precision Example Time amp Date v 06 28 39 PM o2 17 1995 Seale Style Mapping Mode Linear EJ Tiie L Log arent O HH Grid Options D 24 hour HH MM 35 Py O es Seconds Precision g Date rd BH Y Axis Scaling Factors Ho dH H MM S5 Emor ee eae Oo 2 2 Digit Year 0170171395 D YMD wi 4 Digit Year C e You can format for either absolute time or date or both If y
175. 95 NT and UNIX filenames can have 255 characters including the vi extension To avoid complications either save VIs with short names or save them into a VI library A VI library is a single file that can contain multiple VIs A library name must conform to platform limits but VIs in libraries can have names up to 255 characters regardless of platform Thus VI libraries are the most convenient format for transferring VIs because libraries eliminate most file system dependencies See the Saving VIs section in Chapter 2 Building VIs for more information on creating VI libraries Separator Character Differences If you are developing a VI for use on multiple platforms do not use any of the platform specific path separator characters and in your filenames Avoid any special characters in your filenames because these can be interpreted differently by different file systems For example hidden files in UNIX begin with a period Resolution and Font Differences Another portability issue concerns differences in screen resolution and fonts Fonts can vary from platform to platform so after porting a VI you might have to choose new fonts to obtain an appealing display When designing VIs keep in mind that there are three fonts which best map between platforms the Application font the System font and the Dialog font These predefined fonts and the real fonts they map to are as follows e The Application font is the d
176. AI Acquire Waveform G Programming Reference Manual 26 6 National Instruments Corporation Screen Display Chapter 26 Performance Issues VI If you need to acquire 100 points you could use the AI Sample Channel VI in a loop with a Wait function to establish the timing Or you can use the AI Acquire Waveform VI with an input indicating that you want 100 points You can produce much higher and more accurate data transfer rates by using the AI Acquire Waveform VI because it uses hardware timers to manage the data transfer In addition overhead for the AI Acquire Waveform VI is roughly the same as the overhead for a single call to the AI Sample Channel VI even though it is transferring much more data Updating controls on a front panel can frequently be one of the most time expensive operations in an application This is especially true if you use some of the more complicated displays such as graphs and charts This overhead is minimized to a certain extent by the fact that most of the controls are intelligent they do not redraw when they receive new data if the new data is the same as the old data Graphs and charts are exceptions to this rule If redraw rate becomes a problem the best solutions are to reduce the number of controls you use and keep the displays as simple as possible In the case of graphs and charts you can turn off autoscaling scale markers and grids to speed up displays If you have controls that are overl
177. Arrays in Other Systems Most programming languages have arrays although few have the number of built in array functions that G contains Other languages typically stop at the fundamental array operations of extracting an element or replacing an element leaving it to the users to build more complex operations themselves G has these fundamental operators so you can map a program in another language directly to a VI in G but you usually can create a simpler and smaller diagram if you start over in G and use the higher level array functions of G The example that follows shows a fragment of a C program that sums the squares of the elements of an array the direct translation to a G block diagram and two redesigned versions that are more efficient than the translation G Programming Reference Manual 14 16 National Instruments Corporation Chapter 14 Array and Cluster Controls and Indicators sum 0 for i 0 i lt 100 i sum x i x il C Code Fragment G Optimal Version EAR The indexing operation for extracting an element is represented in C by ar brackets following the array name and enclosing the index In G this operation is represented by the Index Array function icon shown at Index Array seer left The array is wired to the top left terminal the index is wired to the function icon National Instruments Corporation 14 17 G Programming Reference Manual Chapter 14 Array and Cluster Controls and In
178. Blinking Attribute By using the Blinking Attribute you can read or set the blink status of an object If you set this attribute to TRUE a front panel object blinks The blink rate and colors are set in the Preferences dialog box When you set this attribute to FALSE the object stops blinking G Programming Reference Manual 20 8 National Instruments Corporation Chapter 20 Attribute Nodes In the following illustration the front panel indicator is set to blinking Block Diagram Front Panel Normal Front Panel Blinking digital contral digital control digital contral a dom gt Position Attribute You can set or read the position of the upper left corner of an object on the front panel with the Position Attribute The position is determined in units of pixels relative to the origin of the Panel window which is initially the top left corner of the window but may be somewhere else if you have scrolled the window This attribute consists of a cluster of two unsigned long integers The first item in the cluster Left is the location of the left edge of the control relative to the origin of the Panel window and the second item in the cluster Top is the location of the top edge of the control relative to the top edge of the Panel window By activating the Position Attribute Node the digital control changes its location on the front panel in the following illustration digital control National Instruments Corpo
179. Case Structure 3 13 illogical selections 3 13 local variable in Case Structure 3 13 locals and front panel terminals within loops 3 13 example 3 14 number of connections 3 12 rules and recommendations 3 11 to 3 14 similarity to removing and replacing selected object 3 11 undoing subVIs with Revert option note 3 11 creating icons 3 2 to 3 4 black and white vs color icons 3 3 Cancel button 3 4 cutting copying and pasting icons note 3 4 dropper tool 3 3 Edit icon option 3 2 fill bucket tool 3 3 filled rectangle tool 3 4 foreground background tool 3 4 Icon Editor 3 2 line tool 3 3 OK button 3 4 pencil tool 3 3 rectangle tool 3 3 select tool 3 4 text tool 3 4 Undo button 3 4 National Instruments Corporation I 19 finding VIs objects and text 3 23 to 3 29 Find dialog box 3 24 to 3 29 finding next and previous search items 3 29 narrowing search scope 3 27 to 3 28 Search Results window 3 28 to 3 29 text 3 26 to 3 27 VIs and other objects 3 24 to 3 25 hierarchical design 3 1 terminal connections 3 5 to 3 10 assigning to controls and indicators 3 6 to 3 8 confirming terminal connections 3 9 to 3 10 defining patterns 3 5 deleting terminal connections 3 9 to 3 10 required recommended and optional connections 3 8 to 3 9 selecting and modifying patterns 3 6 white terminal indicating incomplete connection note 3 8 building VIs 2 1 to 2 30 aligning ob
180. Corporation 17 3 G Programming Reference Manual Chapter 17 Wiring the Block Diagram You can double click with the Wiring tool to begin or terminate a wire in an open area as shown following terminating in an open area beginning in an open area When wires cross a small gap appears in the first wire drawn as if it were underneath the second wire as shown here When you are wiring a complicated built in node or subVI it is important to pay attention to the wire stubs and the tip strips that appear as the Wiring tool approaches the VI icon Wire stubs the truncated wires shown around the VI icon to the left indicate the data type by their style thickness and color For details refer to the Quick Reference Card Dots at the end of the stubs indicate inputs although outputs have no dots The direction in which the stubs are drawn indicates the suggested direction to wire to produce clean diagrams When you wire a terminal the wire stub no longer appears for that terminal G Programming Reference Manual 17 4 National Instruments Corporation Chapter 17 Wiring the Block Diagram You also might want to take advantage of the Help window feature that highlights each connector pane terminal With this feature you can see exactly where wires need to connect The three connections of the Add function are shown as a simple example in the following illustration Block Diagram Help Window Note The feature just
181. DLL With this option you can select the default size in elements to allocate for arrays When a Call Library Node function has an array as an argument the converter drops an Initialize Array function to create an array to pass into the node The initial size of such arrays is specified by the Default Size for Array Parameters option A 23 12 National Instruments Corporation Chapter 23 Calling Code from Other Languages warning is generated in the out file so that you can easily find VIs containing this construct and handle special cases individually Selecting OK at the main LabWindows CVI Function Panel Converter dialog box brings up a file dialog box so you can select the library corresponding to the FP file being converted if the Create Library Call option is set Canceling this dialog box simply leaves the library path unspecified in the Call Library Function node it does not abort conversion After you click OK the converter brings up a working status dialog box to display the name of each new VI as it is created A log file named prefix out is created listing all the VIs that were created and any warnings or errors that occurred during conversion If any warnings or errors do occur you are notified to look at this file when conversion is complete National Instruments Corporation 23 13 G Programming Reference Manual Chapter Understanding the G Execution System This chapter explains VI multitasking and exec
182. Default Directory take place immediately iz Note All changes to the Library Directory Temporary Directory and Default Directory options take effect when you relaunch your G development environment G Programming Reference Manual 7 4 National Instruments Corporation Chapter 7 Customizing Your G Environment VI Search Path The VI Search Path is used only when your G development environment searches for a subVI control or external subroutine that is not in the expected location It lets you list the path of directories for G to search When you edit the search path you are given more options than for the other paths you can add new items in specific locations remove paths and select from a list of special paths UI Search Path w O Use default foundviel twilib 1 Browse l Insert Before Insert After The list contains paths that your G development environment searches in the order that it searches them To add a new directory you first need to decide when your G development environment searches that directory relative to the other directories Select an adjacent directory from the list Then use either the Browse button which displays a file dialog box or the special pull down menu which contains a list of special paths to select the directory that your G development environment searches You also can edit or enter this path in the string control next to these options Finally use Insert Befo
183. EW User Manual Once you have verified that the stub VIs provide the functionality you expect you can determine which components individual developers should work on To simplify matters you might place the major stub VIs in separate directories or VI libraries which can then be managed by different developers Keeping Master Copies You should probably keep the master copies of your project VIs on a single computer You can institute a check in check out policy to ensure control over what changes in your VIs With this policy a developer could check out a copy of the VIs like checking a book out of the library During that time nobody should touch the files that the developer has checked out The developer would then check in the finished VIs after making any changes There are several applications that can help control access to files and maintain different revisions of files There is currently no way of performing a comparison between VIs other than a visual comparison so you need to be meticulous with your check in check out policy to avoid multiple developers working on the same VIs at the same time VI History Window In addition to its front panel and block diagram a VI has a History window that displays the development history of the VI including revision numbers Each user who changes a VI can record any changes made in the history This feature should help users keep track of changes to a VI as they are made However the VI
184. G Programming Reference Manual Index printing VIs 5 1 to 5 9 active window Print Window option 5 2 AESend Print Document VI 5 1 alternative printing methods 5 9 configuring printouts 5 1 to 5 2 overview 5 1 PostScript printing 5 2 programmatic printing 5 7 to 5 8 controlling when printouts occur 5 7 enabling disabling 6 6 enhancing printouts 5 7 to 5 8 setting page layout 5 8 selecting print options 5 3 to 5 6 choosing layout options 5 4 creating custom print settings 5 4 to 5 6 Print Documentation dialog box 5 3 printing section headers 5 6 setting printout formats 5 3 to 5 4 Serial Port VIs 5 1 System Exec VI 5 1 priorities in multitasking See multitasking Probe tool creating probes 4 25 to 4 26 purpose and use 2 5 using 4 23 to 4 25 Profile window 26 1 to 26 5 illustration 26 2 memory information 26 5 Reset button 26 2 Save button 26 2 Snapshot button 26 2 Start button 26 2 SubVI s Time 26 3 timing information 26 4 to 26 5 Total Time 26 3 VI Time 26 3 viewing results 26 3 programmatic printing 5 7 to 5 8 controlling when printouts occur 5 7 enabling disabling 6 6 G Programming Reference Manual enhancing printouts 5 7 to 5 8 setting page layout 5 8 Project menu Find 3 23 Find Next 3 29 Search Results 3 28 Show VI Hierarchy 3 15 This VI s SubVIs 4 16 Unopened SubVIs 4 16 Prompt for comment when this VI is closed option 6 4 Prompt for comment when this VI is sav
185. I simultaneously If you try to call a non reentrant subVI from more than one place one call executes and the other call waits for the first to finish before executing If you make a VI reentrant using VI Setup each instance of the call maintains its own state of information Then the execution system runs the same subVI simultaneously from multiple places Reentrant execution is useful in the following situations e When a VI waits for a specified length of time or until a timeout occurs e When a VI contains data that is not to be shared between multiple instances of the same VI as opposed to a global variable which is a VI whose data you want to share You begin reentrant execution through the Execution Options of the VI Setup dialog box If you select reentrancy several other options become unavailable including the following e Opening a front panel when loaded e Opening a front panel when called e Execution highlighting e Single stepping These options are disabled because the subVI must switch between different copies of the data and different execution states with each call making it impossible to display its current state continuously Examples in which You Should Use Reentrancy Using a VI That Waits The following reentrant example discusses a VI called Snooze which 22 takes hours and minutes as input and waits until that time arrives If you want to use this simultaneously in more than one location the VI n
186. Is Displays a palette of all VIs in memory that are not located in vi lib Type Defs Displays a palette of all type definitions in memory that are not located in vi lib Globals Displays a palette of all global VIs in memory that are not located in vi lib Objects in vi 1ib Displays all VIs type definitions and global variables that are located in vi lib Others Displays a menu from which you can select Attribute Nodes breakpoints and front panel terminals VIs by Name Invokes the Select VIs by Name dialog box which displays all VIs in memory by name in alphabetical order You can type the name of the object to jump quickly to the item in the list you want With the three checkboxes VIs Globals and Type Defs you can include and exclude different types of objects to be displayed in the list box 3 25 G Programming Reference Manual Chapter 3 Building SubVis Finding Text To search for specific text click on the Text button in the Find dialog box The dialog box is displayed as follows Find Search for objects Text Find What e e Match Case C Match whole Word More Options O Regular Expression mearch Scope lt All Us in Memory gt O Search in Hierarchy window EJ Search Vis in vitib Search String Options You can type in the text you want to find and optionally limit the scope of the search to specific areas of VIs front panel block diagram
187. Is 27 1 overview 27 1 picture differences 27 4 to 27 5 questions about B 6 resolutions and font differences 27 2 to 27 4 separator character differences 27 2 printing 5 1 to 5 9 active window 5 2 alternative printing methods 5 9 configuring printouts 5 1 to 5 2 history information 5 6 options 5 3 to 5 6 programmatic 5 7 to 5 8 running 4 1 to 4 4 running repeatedly 4 5 saving 2 27 to 2 30 individual VI files 2 28 to 2 29 VI libraries LLBs 2 29 to 2 30 stopping 4 4 structure 1 2 VIs by Name option 3 25 National Instruments Corporation VIs option Select Objects menu 3 25 Visible Attribute 20 7 Visible Name option 15 34 void data type 23 5 W Warning button accessing Error List window 4 10 waveform and XY graphs 15 2 to 15 22 creating multiplot graph 15 5 to 15 11 waveform graph data types 15 5 to 15 9 XY graph data types 15 9 to 15 11 creating single plot graph 15 3 to 15 4 waveform graph data types 15 2 to 15 3 XY graph data types 15 3 to 15 4 definition 15 2 graph options 15 11 to 15 22 illustration 15 12 legend options 15 19 to 15 22 scale options 15 12 to 15 17 illustration 15 2 waveform chart 15 22 to 15 29 cursors not supported 15 25 data types 15 22 to 15 25 front panel data logging note 4 6 options 15 25 to 15 29 chart pop up menu 15 25 scope chart update mode 15 27 stacked versus overlaid plots 15 28 to 15 29 strip chart update mode 15 27 sweep cha
188. List window to see a list of hidden objects as long as the Show Warnings checkbox is selected To help avoid corruption caused 4 16 National Instruments Corporation Chapter 4 Executing and Debugging Vis and SubVIs by hidden VIs you can indicate that inputs to VIs are required for information see Required Recommended and Optional Connections for SubVIs in Chapter 3 Building SubVIs Recognizing Undefined Data There are two mnemonics that can appear in floating point digital displays to indicate faulty computations or meaningless results NaN not a number is the symbol that represents a particular floating point value that operations such as taking the square root of a negative number can produce nf is another special floating point value produced for example by dividing one by zero Undefined data can corrupt all subsequent operations Floating point operations propagate NaN and Inf which when explicitly or implicitly converted to integers or Booleans become meaningless values For example dividing one by zero produces Inf but converting that value to a word integer produces the value 32 767 which appears to be a normal value Before converting to integer types check intermediate floating point values for validity unless you are sure that this type of error does not occur in your VI Executing a For Loop zero times can produce unexpected values For example the output of an initialized shift register is the initia
189. NSTRUMENTS MAKES NO WARRANTIES EXPRESS OR IMPLIED AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE CUSTOMER S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER NATIONAL INSTRUMENTS WILL NOT BE LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA PROFITS USE OF PRODUCTS OR INCIDENTAL OR CONSEQUENTIAL DAMAGES EVEN IF ADVISED OF THE POSSIBILITY THEREOF This limitation of the liability of National Instruments will apply regardless of the form of action whether in contract or tort including negligence Any action against National Instruments must be brought within one year after the cause of action accrues National Instruments shall not be liable for any delay in performance due to causes beyond its reasonable control The warranty provided herein does not cover damages defects malfunctions or service failures caused by owner s failure to follow the National Instruments installation operation or maintenance instructions owner s modification of the product owner s abuse misuse or negligent acts and power failure or surges fire flood accident actions of third parties or other events outside reasonable control Under the copyright laws this publication may not be reproduced or transmitted in any form electronic or mechanical including photocopying recording storing in an information ret
190. Programming Reference Manual About This Manual Front Panel Objects Chapter 6 Setting up VIs and SubVIs discusses how you can use the VI Setup and SubVI Node Setup dialog boxes to customize the behavior of a subVI You can use these dialog boxes to create subVIs that show their panels when they are called and to enable and disable features of a panel such as the scrollbars the toolbar and the window resizing capability Chapter 7 Customizing Your G Environment discusses how to customize your G environment by setting preferences and by changing the contents of the Controls and Functions palettes Chapter 8 Introduction to Front Panel Objects introduces the front panel and its two components controls and indicators It also explains how to import graphics from other programs to use in your controls Chapter 9 Numeric Controls and Indicators explains how to create operate and configure the various styles of numeric controls and indicators Chapter 10 Boolean Controls and Indicators discusses how to create operate and configure Boolean controls and indicators Chapter 11 String Controls and Indicators discusses how to use string controls and indicators and the table Chapter 12 Path Controls and Indicators and Refnums describes how to use file path controls and refnums which are available from the Controls Path amp Refnum palette Chapter 13 List and Ring Controls and Indicators describes the listbox and
191. Return gt key on Macintosh and HP UX to find the next node that matches the search string To find the previous node that matches you can press the left or up arrow key or lt Shift Enter gt on Windows and Sun or lt Shift Return gt on Macintosh and HP UX Finding Vis Objects and Text When developing an application consisting of multiple subVIs or even a single large VI you might want to find occurrences of a particular object or string of text The Project Find command can help you find all instances of the following objects with the names you indicate e VIs e Built in functions e Type definitions e Global variables e Local variables e Attribute Nodes e Breakpoints e Front panel terminals e Text For information on type definitions see the Type Definitions section in Chapter 22 Custom Controls and Type Definitions For information on local and global variables see Chapter 21 Global and Local Variables For information on Attribute Nodes see Chapter 20 Attribute Nodes For information on breakpoints see the Placing Breakpoint Tools section of Chapter 4 Executing and Debugging VIs and SubVIs In addition to the Find command many objects have pop up options that help you quickly find related objects For example if you pop up on a control an option helps you find the corresponding terminal as well as any local variables or Attribute Nodes associated with it National Instruments Corporation
192. SE array 4K array C4kK for the indicator National Instruments Corporation 26 23 G Programming Reference Manual Chapter 26 Performance Issues The best solution shown in the following illustration is to convert the random number to single precision as it is created before you create an array Doing this avoids the conversion of a large data buffer from one data type to another Avoid Constantly Resizing Data If the size of an output is different from the size of an input the output does not reuse the input data buffer This is the case for functions such as Build Array String Concatenate and Array Subset which increase or decrease the size of an array or string When working with arrays and strings try to avoid constantly using these functions because your program uses more data memory and executes more slowly because it is constantly copying data Example 1 Building Arrays As an example consider the following diagram which is used to create an array of data This diagram creates an array in a loop by constantly calling Build Array to concatenate a new element The input array is not reused by Build Array Instead the VI continually resizes the output buffer to make room for the new array and copies data from the old array to the new array The resulting execution speed is very slow especially if the loop is executed many times G Programming Reference Manual 26 24 National Instruments Corporation
193. Sar Single precision Orange floating point 2 Complex Opanse extended precision floating point Complex double precision Orange floating point Complex single precision Orase floating point Unsigned 32 bit integer Blue 6 2 National Instruments Corporation Chapter 16 Introduction to the Block Diagram Table 16 1 G Control and Indicator Terminal Symbols Continued Control Indicator Description Color Unsigned 16 bit integer Blue Unsigned 8 bit integer Blue 32 bit integer long word Blue 16 bit integer word Blue 8 bit integer Blue Cluster Brown or Pink SGL Array Varied Path Aqua oa Refnum Aqua TF TF Boolean Green abc abc String Pink Constants Constants are terminals on a block diagram that supply data values directly to the block diagram User defined constants are defined prior to program execution and you cannot change their values during execution Universal constants have fixed values User Defined Constants The easiest way to create a constant is to pop up on an input or output and select Create Constant These constants are also available from various palettes in the Functions palette depending on their type Most are located at the bottom or top of the relevant palette such as the numeric enumerated and ring constants in the bottom row or the Numeric palette Three constants the color box listbox symbol ring and error ring constants are loca
194. Setup To access the VI Setup dialog box pop up on the VI icon in the upper right corner of the front panel and select VI Setup or double click on the VI icon See Chapter 6 Setting up VIs and SubVIs for more details National Instruments Corporation B 15 G Programming Reference Manual Appendix B Common Questions about G How do disable mouse interrupts to improve performance Interrupts caused by moving the mouse or clicking it on an item take CPU time In some extremely time critical applications this interrupt activity can result in a loss of data or some other problem with the application There is no known way to disable mouse interrupts while an application is running Make sure that the mouse does not move during the time critical portions of your application G Programming Reference Manual B 16 National Instruments Corporation Appendix Customer Communication For your convenience this appendix contains forms to help you gather the information necessary to help us solve your technical problems and a form you can use to comment on the product documentation When you contact us we need the information on the Technical Support Form and the configuration form if your manual contains one about your system configuration to answer your questions as quickly as possible National Instruments has technical assistance through electronic fax and telephone systems to quickly provide the information you need Our elec
195. a simple or a complex view by pressing the second button at the bottom of the Help window or by toggling the Help Simple Help option The simple view emphasizes the important connections and de emphasizes the other less critical connections In this view labels of required connections are in bold text and recommended connections are in plain text Wire stubs appear in the place of the optional inputs and outputs that are not displayed to inform you that additional connections National Instruments Corporation 1 7 G Programming Reference Manual Chapter 1 Introduction to G Programming exist and that choosing the complex view will display them The following illustration shows the simple view of a File I O VI LJ Hel format 8 2f file path dialog if empty Hiza new file path Mot 4 Path i 2D data AE 1E data H ol wire stub append to file new file F 2 transpose tno Fi ebion ia showing optional input Write To Spreadsheet File_vi Fo In the complex view the Help window shows all inputs with wires pointing to the left and outputs with wires pointing to the right Labels of optional inputs are in gray text The following illustration shows the complex view of a File I O VI format 3f file path dialog if empty i new file path Not A F 2D data 1D data append to file new file FJ optional input displayed transpose no F aid manipis PY oot Also the fil
196. a test from the ring control or to fill in information for other controls When the user selects a test the string corresponding to the numeric value of the ring control is read and then passed to a VI that executes the test select a test i H bStrings Using a Double Clicked Listbox Item The Double Click attribute is a read only attribute specific to listboxes This attribute indicates the item on the front panel on which you double clicked The value of the Double Click attribute is set when you double click on an item or type lt Enter gt Windows or UNIX or lt Return gt Macintosh and Sun after you select an item The double click value is 1 if nothing has been double clicked It is reset to 1 after it is read using the Attribute Node It also is reset to 1 if the you select a different item or if you set any of the other attributes National Instruments Corporation 20 13 G Programming Reference Manual Chapter 20 Attribute Nodes The following illustration is an example of how to use the Double Click Attribute Node to determine what test to execute Listbox 132 Listbox False z Listhoxi i Doub Double Click Fw ouble Click Execute Test Oo TF The False Case is executed when double click is 1 and the True Case is executed when the user has double clicked on a test number in the listbox
197. about to change to the scale part Control 3 Control Parts x File Edit Operate Current Part Name Label Part Position and Dimensions Top Height 20 Lett s4 width as The Control Parts window shows you the exact position and size of the current part These values are pixel values When you move or resize a part in the Control Editor the position and size in the Parts window are updated You also can enter the position and size values directly in the Control Parts window to move or resize the part in the Control Editor This is useful when you need to make two parts exactly the same size or align one part with another In the preceding illustration the Parts G Programming Reference Manual 22 8 National Instruments Corporation Chapter 22 Custom Controls and Type Definitions window displays the position and size of name label of the slide the upper left corner of the label is at the pixel coordinates 74 84 and the label is 20 pixels high by 45 pixels wide The Control Parts window disappears if you switch to some other window The Control Parts window reappears when you return to the Control Editor Customize Mode Pop Up Menus for Different Parts In customize mode the pop up menu for the control as a whole is replaced by a pop up menu for each part When you pop up on a part you see a menu with some options available in edit mode and some options available only in customize mode Differen
198. adding cosmetic parts to custom controls 22 17 to 22 18 adding to Controls palette 22 1 22 5 applying changes from custom controls 22 3 to 22 4 caveats 22 18 to 22 19 Control Editor 22 1 to 22 3 Control Editor Parts window 22 7 to 22 9 controls as parts 22 15 to 22 17 cosmetic parts 22 9 to 22 14 independent pictures 22 12 to 22 14 more than one picture 22 11 to 22 12 creating 22 1 to 22 4 current part 22 8 independence from source file 22 5 independent parts 22 6 to 22 7 making icons 22 5 opening 22 5 pop up menus for different parts 22 9 purpose and use 22 1 saving 22 4 scale parts 22 15 text parts 22 14 to 22 15 using 22 4 valid custom controls 22 3 to 22 4 National Instruments Corporation Custom format Print Documentation dialog box 5 4 Custom Print Settings dialog box 5 5 Block Diagram 5 6 Controls 5 5 to 5 6 Front Panel 5 5 Icon and Description 5 5 illustration 5 5 List of SubVis 5 6 Print Section Headers option 5 6 VI Hierarchy 5 6 VI History 5 6 Custom probe option 4 25 Custom Probe palette 4 26 Custom Save option 25 4 customer communication xxv C 1 to C 2 customize mode 22 5 to 22 19 adding cosmetic parts to custom controls 22 17 to 22 18 Control Editor Parts window 22 7 to 22 9 controls as parts 22 15 to 22 17 cosmetic parts 22 9 to 22 14 independent parts 22 6 to 22 7 pop up menus for different parts 22 9 scale parts 22 15 selecting 22 5 to 22 6
199. advantage of modularity What you can do is make a single sub VI with a mode input that specifies whether you want to read change or remove a channel or whether you want to zero out the data for all channels as shown in the following illustration mode Channel Names Found used if mode Ch Channel Info p gain used if mode Get channel name lower limit used if modes gain used if mode Change upper limit used if mode lower limit used if mode upper limit fused if modes Al Clear all Channels Get Channel Into Change Channel Into Remove Channel The subVI would contain a While Loop with two shift registers one for the channel data and one for the channel names Neither of these shift registers should be initialized Then inside the While Loop you would place a Case Structure connected to the mode input Depending on the value of the mode you could read and possibly change the data in the shift register G Programming Reference Manual 26 34 National Instruments Corporation Chapter 26 Performance Issues Following is an outline of a subVI with an interface that could handle these three different modes Only the Change Channel Info code is shown moda j Change Channel Into mode Lo J i False Channel Names not found gt add to arra abc ory Channel Info sagen Found atif i used if mode Change or Set eos ey Search 1D Arras channel name ogo g Le m gain ga
200. aeaaea OE pEr ES EEE Ea RE eE siS 2 28 VE Tabranes LEBs e stein La E 2 29 Creating VI Libraries sicessciisssesccsaevencssetbeseg buceesbes e E E T 2 30 Saving in Existing VI Libraries 0 ieee eseeececeeeeeeceeeeeeeeseeeneenee 2 30 Editing the Contents of Libraries eee ce ceseeeeceseeeeeeeeeeeeenes 2 30 Chapter 3 Building SubVIs Hierarchical Desin arreir aene de yd co tesuyeeceysed speusascsad eee diye eE aeeoea 3 1 Creating Sub VIs from VIS 000 0 eee ceesseceseeseceeceseeeeceseeeeceseeeeecseseaecaeesaecaeceaeceeeseeereeeeees 3 1 Creatine the CON vsscsecsseeseeiie vega tid voreeniebtvochentesdgnssenetday stave bineBues ickueebetaunsuaveats 3 2 Defining Connector Terminal Patterns 0 0 0 ee ee ceeeecseensecseenseceeceseeeeneeees 3 5 Selecting and Modifying Terminal Patterns 000 00 eee cess ceeeeeeeeeeeeeeenes 3 6 Assigning Terminals to Controls and Indicators eee ceeeeceeeeeeeeneeeeeenes 3 6 Required Recommended and Optional Connections for SubVIs 3 8 Deleting Terminal Connections 0 0 0 eee ee cseeecseesseceeceseeseceseeseceeeeeeeeeeeseeees 3 9 Confirming Terminal Connections 00 00 eeeceseeseceseeeeceeeeseeeeeeeeseeseaeeeaeeaee 3 10 G Programming Reference Manual vi National Instruments Corporation Table of Contents Creating SubVIs from VI Selections 00 0 0 eee ceceeeceeeeeeseeeeseeceecaeecaecsaseaecneeeseenseeseees 3 10 Rules and Recommendations 00 ce eeeeeeeeeeeeseesseceecescesecesee
201. agram Search 1D Array Any True Returns 1 if not found There are two loops in parallel One of the loops is acquiring data and needs to execute as frequently as possible The other loop is monitoring user input The loops receive equal time because of the way this program is structured The loop monitoring the user s action has a chance to run several times a second In practice it is usually acceptable if the loop monitoring the button executes only once every half second or even less often By calling the Wait ms function in the user interface loop you allot significantly more time to the other loop G Programming Reference Manual 26 8 National Instruments Corporation Chapter 26 Performance Issues Search 1D Array Any TRUE Returns 1 if SubVI Overhead When you call a subVI there is a certain amount of overhead associated with the call This overhead is fairly small on the order of tens of microseconds especially in comparison to I O overhead and display overhead which can range from milliseconds to tens of milliseconds However this overhead can add up in some cases For example if you call a subVI 10 000 times in a loop this overhead might take up a significant amount of time In this case you might want to consider whether the loop can be embedded in the subVI Another option that you might consider is turning certain subVIs into subroutines using the VI Setup Priority option
202. al Forecasting 2 9300 0 4970 3 4270 0 0244 2D Array to Table vi 0 3310 0 0000 0 3310 Month Strings vi Linear Fit vi Ramp Pattern vi Linear Fit Coefficients vi Exponential Fit vi MSE vi Exponential Fit Coefficients vi 1D Linear Evaluation vi There are several things to notice about the window First the collection of memory usage information is optional This is because the collection process can add a significant amount of overhead to the running time of your VIs You must choose whether to collect this data before starting the Profiler by checking the Profile Memory Usage checkbox appropriately This checkbox cannot be changed once a profiling session is in progress The following buttons are available on the Profile window e Start Enables the collection of performance data It is best to start a profiling session while your application is not running This way you can ensure that you measure only complete runs of VIs and not partial runs e Snapshot Views the data that is currently available This gathers data from all the VIs in memory and displays it in the tabular display e Save Saves the currently displayed data to disk as a tab delimited text spreadsheet file This data can then be viewed in a spreadsheet program or by VIs e Reset Erases all the current Profiler information from the table so that you can start a new profiling session
203. al digital displays as explained in the Format and Precision of Digital Displays section of Chapter 9 Numeric Controls and Indicators The options in this dialog box are as follows Default date format Determines whether the month day or year comes first in digital displays Default time format Determines whether time in digital displays is based on a 12 hour or 24 hour clock Date Separator Determines the character used to separate the month day and year in the order selected in the Default date format option of digital displays Time Separator Determines the character used to separate the hours and minutes past the hour in digital displays Note Changes to options in the Time and Date Preferences dialog box take effect immediately National Instruments Corporation 7 21 G Programming Reference Manual Chapter 7 Customizing Your G Environment Miscellaneous Preferences The Miscellaneous Preferences dialog box is shown in the following illustration Preferences Miscellaneous E Show tip strips Use native file dialogs lt lt Windows Macintosh only Allow drop through clicks Use hot menus C Show auto constant labels C Open Vis in run mode The options in this dialog box are as follows Open VIs in run mode Opens VIs in run mode rather than edit mode Show tip strips Toggles the display of Tip strips Windows Macintosh Use native file dialogs Uses the operating system s native
204. all corresponding locals and Attribute Nodes From a global node you can find its corresponding global definition or all other global nodes Conversely global controls have a pop up menu for finding all corresponding global references in memory If more than one result is found the Search Results window appears National Instruments Corporation 3 29 G Programming Reference Manual Executing and Debugging Vis and SubVls Executing VIs Chapter This chapter discusses how to operate and debug VIs and explains how to set up VIs and subVIs for special execution modes Running Vis Run button VI running at top level VI caller is running Run Continuously Cc zt O fa Stop button Pause button You can run a VI by selecting Operate Run or by clicking on the Run button G compiles the VI if necessary While the VI is executing the Run button changes appearance If the VI is running at its top level meaning it has no callers and therefore is not a subVI the Run button changes to look like the illustration shown to the left If the VI is executing as a subVI the Run button changes to look like the illustration shown to the left Press the Run Continuously button to run the VI over and over until you stop or pause execution Pressing the Stop button aborts execution of the top level VI If a VI is used by more than one running top level VI the button appears grayed out Pressing this bu
205. als from the icon pop up menu as shown in the following illustration to see precisely where the terminals are located National Instruments Corporation 16 9 G Programming Reference Manual Chapter 16 Introduction to the Block Diagram Description Show b Replace Create Constant Create Control Create Indicator When terminals are showing select Show Terminals again to show the icon for the function instead When you wire to a function you wire to one of its terminals Some array and cluster functions have a variable number of terminals For example if you build an array of three elements the Build Array function needs three input terminals but if you build one with 10 elements the function needs 10 terminals You can change the number of terminals of the expandable functions by resizing the icon with the Resizing cursor in the same way you resize other G objects as shown in the following illustration You can enlarge or reduce functions but you cannot shrink a function if it causes any wired terminals to disappear You also can change the number of terminals with the Add and Remove commands from the pop up menu for a terminal as shown in the illustration that follows The Remove command removes the terminal on which you popped up and disconnects the wire if the terminal is G Programming Reference Manual 16 10 National Instruments Corporation Chapter 16 Introduction to the Block Diagram wired a
206. alues 9 4 to 9 5 digital numeric pop up menu options 9 3 displaying integers in other radixes 9 4 Enter button for replacing old values 9 2 format and precision of digital displays 9 9 to 9 11 absolute time and date 9 10 to 9 11 example 9 10 Format amp Precision dialog box 9 9 illustration 9 2 incrementing and decrementing 9 2 to 9 3 G Programming Reference Manual Index numeric range checking 9 7 to 9 9 Operating tool 9 2 purpose and use 9 2 to 9 3 range options 9 6 to 9 7 Data Range dialog box 9 7 floating point numbers table 9 6 numeric range checking 9 7 to 9 9 range of extended floating point numbers note 9 6 valid values 9 2 Digital Display option Show menu 2 13 15 25 digital displays hiding 2 13 digital numeric pop up menu options 9 3 directories setting 7 3 to 7 4 7 5 Disable Indexing option 18 8 Disabled Attribute 20 7 to 20 8 Disconnect All Terminals command 3 10 Disconnect from Type Def option 22 22 Disconnect This Terminal command 3 10 discontiguous data types A 12 disk preferences setting See Performance and Disk Preferences dialog box Display Types option 11 3 to 11 5 distributing objects 2 12 distributing VIs considerations 25 2 to 25 4 using Save with Options 25 3 to 25 4 documentation printing See Print Documentation dialog box documentation National Instruments conventions used in manual xxiv xxv organization of manual xxi xxiv advanced G topics xxiii
207. am runs the VI until all nodes on the block diagram of the VI have executed at which time execution pauses National Instruments Corporation 4 19 G Programming Reference Manual Chapter 4 Executing and Debugging VIs and SubVIs Step Over button bal Step Into button e Step Out button Selecting one of the VIs on the call stack runs that VI until it is finished At that point the caller of the selected VI pauses Caller2 vi Caller3 vi Using Step Buttons The step buttons are as follows Press the Step Over button to execute a structure sequence loop etc or a subVI and then pause at the next node The keyboard shortcut is lt Ctrl gt Windows lt command gt Macintosh lt met a gt Sun or lt Alt gt HP UX followed by the right arrow key Press the Step Into button to execute the first step of a subVI or structure sequence loop etc and then pause at the next step of the subVI or structure The keyboard shortcut is lt Ct r1 gt Windows lt command gt Macintosh lt met a gt Sun or lt Alt gt HP UX followed by the down arrow key The step buttons affect execution only in a VI or subVI that is in single step mode If a VI in single step mode has one subVI that is also in single step mode and one that is in normal execution mode the first subVI single steps when called but the second executes normally when called Press the Step Out button to finish executing the current block diagram s
208. ames must be lowercase Table 19 1 shows the names of the Formula Node functions Table 19 1 Formula Node Functions Function Corresponding G Description Function Name abs x Absolute Value Returns the absolute value of x acos x Inverse Cosine Computes the inverse cosine of x in radians acosh x Inverse Hyperbolic Computes the inverse hyperbolic Cosine cosine of x in radians asin x Inverse Sine Computes the inverse sine of x in radians asinh x Inverse Hyperbolic Computes the inverse hyperbolic Sine sine of x in radians atan x Inverse Tangent Computes the inverse tangent of x in radians atanh x Inverse Hyperbolic Computes the inverse hyperbolic Tangent tangent of x in radians National Instruments Corporation 19 5 G Programming Reference Manual Table 19 1 Formula Node Functions Continued Function Corresponding G Description Function Name ceil x Round to Infinity Rounds x to the next higher integer smallest int is greater than or equal to x cos x Cosine Computes the cosine of x in radians cosh x Hyperbolic Cosine Computes the hyperbolic cosine of x in radians cot x Cotangent Computes the cotangent of x in radians 1 tan x csc x Cosecant Computes the cosecant of x in radians 1 sin x exp x Exponential Computes the value of e raised to the x power expm1 x Exponential Arg 1 Computes the value of e raised
209. an update or read headings using the Attribute Node The index display indicates which cell is visible at the upper left corner of the table You can operate these indices just as you do on an array Resizing Tables Rows and Columns You can resize the table from any corner with the Resizing tool You can resize individual rows and columns in a table by dragging one of the border lines with the Positioning tool When the tool is placed properly G Programming Reference Manual 11 6 National Instruments Corporation Chapter 11 String Controls and Indicators to drag a line one of the drag cursors shown in the following illustration appears Click on a line and drag it to resize the row or column pa ol AF You can use the lt Shift gt key while dragging a border line to size multiple rows or columns to be all the same size If the row or column you are resizing is inside an area of the table you have selected outlined in blue or bold all the rows or columns in the table also are equally sized Thus the uneven horizontal rows in the following illustration to the left become evenly spaced in the illustration to the right Entering and Selecting Data Tables You can use the keyboard to enter data into a table rapidly Click inside a cell with either the Operating tool or the Labeling tool type in your data The lt Enter gt Windows and HP UX or lt Return gt Macintosh and Sun key on the alphanumeric keyboard ente
210. and data related to the number of blocks used The execution system uses independent blocks of memory for arrays strings paths and pictures from the Picture Control Kit Large numbers of blocks in the memory heap of your application can cause an overall degradation of performance not just execution The categories of Memory Usage are the following e Average Bytes Average number of bytes used by the data space of this VI per run e Min Bytes Minimum number of bytes used by the data space of this VI for an individual run e Max Bytes Maximum number of bytes used by the data space of this VI for an individual run e Average Blocks Average number of blocks used by the data space of this VI per run e Min Blocks Minimum number of blocks used by the data space of this VI for an individual run National Instruments Corporation 26 5 G Programming Reference Manual Chapter 26 Performance Issues e Max Blocks Maximum number of blocks used by the data space of this VI for an individual run Speeding Up Your Vis The compiler compiles your VIs and produces code that generally executes very quickly When working on time critical applications you might want to do all you can to obtain the best performance out of your VIs This section discusses factors that affect execution speed and suggests some programming techniques to help you obtain the best performance possible You should examine the following items to deter
211. and max labels in the text display or on the slide itself Change to Indicator Find Terminal Show Data Operations Create Key Navigation Replace Representation Data Range Format amp Precision Add Slider Fill Options Scale G Programming Reference Manual 9 18 National Instruments Corporation Chapter 9 Numeric Controls and Indicators You can pop up on the text display and select Show Digital Display to find out what numeric values are associated with the text labels you create These values always start at zero on the bottom of vertical slides and on the left or right of horizontal slides and increase by one for each text label Use the Add Item After or Add Item Before option from the text display pop up menu to create new labels as shown in the following illustration volts DC Format amp Precision Add Item After Add Item Before Reminie pipin OOhrs Volts AC Volts AC Change to Indicator birg Show Data Operations Create Attribute Node Volts DC You also can press lt Shift Enter gt Windows and HP UX or lt Shift Return gt Macintosh and Sun to advance to a new item when you are editing the existing items National Instruments Corporation 9 19 G Programming Reference Manual Chapter 9 Numeric Controls and Indicators Filled and Multivalued Slides The Numeric palette contains four controls that are configured to fill from the minimum to the slider va
212. and reload the code Control control does not match Edit the control to match or pop up and update or its type definition disconnect the type definition VI from the control Enumeration has duplicate All the items in an enumeration control must be entries unique and distinct National Instruments Corporation 4 11 G Programming Reference Manual Chapter 4 Executing and Debugging VIs and SubVIs Table 4 1 Error Messages Continued Error Messages Descriptions More Errors G shows only 100 errors at one time Unlisted errors appear after you fix the listed errors For Loop N is unwired and there are no input indexing tunnels Unless N is wired or an array is indexed on input the loop cannot determine how many iterations to execute Global or Local Variable component doesn t exist named The name of a variable has changed since you last loaded the VI and the name in the global or local variable no longer matches Pop up on the variable and select another name Global Variable subVI is G was not able to find the global subVI when it missing loaded the calling VI perhaps because you changed the name Replace the bad global subVI with a good one Node A subroutine priority VI You cannot use an asynchronous function such as cannot contain an asynchronous node Wait in a VI that has a priority level equal to subroutine Right Shift Register undefined type
213. and replace the existing National Instruments Corporation 7 3 G Programming Reference Manual Chapter 7 Customizing Your G Environment path or browse the file dialog box to select a path This is shown in the following illustration path category current value new value Library Directory W Use default CAPROGRAM FILES a7 The Library Directory shows the absolute pathname to the directory containing vi lib and any library directories you supply The default is the directory containing your G development environment The Temporary Directory shows the absolute pathname to the directory for temporary files which varies according to platform as follows e Windows The default is the directory containing your G development environment e Macintosh In System 6 the default is the G folder Under System 7 the default is an invisible folder called Temporary Items at the top of your hard drive which is where Apple recommends that temporary files be stored If your G development environment crashes the temporary files are moved into the trash when you restart e UNIX The default is the tmp directory The Default Directory shows the absolute pathname to the default directory which is the initial directory the file dialog box displays The Default Directory function in the Functions File I O File Constants palette also returns this value The default is the current working directory Changes to the
214. another way to turn on programmatic printing If you select Print Header a header including the VI name the last modification date and the page number appears at the top of each page If you select Scale to Fit and the panel is bigger than a single page the printout scales down to as little as one fourth the original size to fit the panel on as few pages as possible If you select Surround Panel with Border G prints a box around the panel G Programming Reference Manual 5 8 National Instruments Corporation Chapter 5 Printing VIs Using Alternative Printing Methods You might find that the previously mentioned method of printing is not appropriate for your application There are some additional techniques that address various printing concerns For example the previous method of printing is geared towards printing an entire page of data In some applications you might prefer to print data on a line by line basis If you have a line based printer connected to your serial port you can use the Serial Port VIs to send text to the printer Doing this generally requires some knowledge of the command language of the printer but has worked well for a number of applications developed by G users If G cannot print data the way you want you might consider using another application to print your data by saving the data to a file and then printing from the other application National Instruments Corporation 5 9 G Programming Refere
215. any function or VI on the palette The editor then splices the node you choose into the wire on which you popped up You must be careful to check the wiring if the node has more than one input or output terminal however because the wires might not connect to the terminal you expected G Programming Reference Manual 16 12 National Instruments Corporation Chapter 16 Introduction to the Block Diagram Adding Constants Controls and Indicators Automatically Instead of creating a constant control or indicator by selecting it from a menu and then wiring it manually to a terminal you can pop up on the terminal and choose Create Constant Create Control or Create Indicator to create an object with an appropriate data type automatically Assuming it makes sense to do so the constant control or indicator created is wired automatically for you For example if you need a constant for the position mode input of a File T O function you can pop up on the input and select Create Constant The editor creates an enumerated type for you Assuming the mode input is not wired already to something else the new constant is wired automatically Online Help Description Show gt Replace gt Create Control Create Indicator Other useful places to pop up include the outputs of functions or VIs constants and terminals for front panel controls or indicators National Instruments Corporation 16 13 G Programming Reference Manual
216. any of the active three step buttons to proceed to the next step The step button you press determines where the next step executes If you idle your cursor over any of the step buttons a Tip strip appears with a description of what the next step will be if you press that button G Programming Reference Manual 4 18 National Instruments Corporation Chapter 4 Executing and Debugging VIs and SubVIs You might want to use execution highlighting as you single step through a VI so you can follow data as it flows through the nodes See the Execution Highlighting section in this chapter An Example of Single Stepping through a VI The following illustration shows an example of a VI that is single stepping Caller 1 vi This VI currently is running on behalf of the VI Caller 3 vi The subVI Fibonacci vi currently is executing you can tell this by the arrow glyph on the Run button The VI Factorial vi is the next node to be executed Clicking on the Step Into button opens its block diagram and starts single stepping Clicking on the Step Over button executes the subVI and pauses Clicking on the Step Out button finishes executing the current frame of the loop and pauses N After stepping into the subVI Fibonacci vi and stepping into the loop clicking on the Step Out button and holding down the mouse for a second a menu appears from which the user can select how far the VI should execute before pausing Selecting Block Diagr
217. appears when you select Sub VI Node Setup from the node pop up menu of a subVI on the block diagram Subli Node Setup LI Open Front Panel when loaded OI Show Front Panel when called These options are a subset of the options in the VI Setup dialog box The difference between the two sets of options is that you use the SubVI Setup dialog box to specify options that relate to a specific call to a subVI although you use the subVI execution options of VI Setup to specify the behavior of all calls to that VI G Programming Reference Manual 6 6 National Instruments Corporation Chapter Customizing Your G Environment This chapter discusses how to customize your G environment by setting preferences and by changing the contents of the Controls and Functions palettes Setting G Preferences Preferences Dialog Box Options To customize your application and configure some default parameters you use the various Preferences dialog boxes You access the Preferences dialog boxes by selecting Edit Preferences as shown in the following illustration Preferences User Name National Instruments Corporation 7 1 G Programming Reference Manual Chapter 7 Customizing Your G Environment Use the pull down menu at the top of the dialog box to select among the different categories of preferences as shown in the following illustration Paths Performance and Disk Front Panel Block Diagram Debugging C
218. apped with other objects their display rate is cut down significantly The reason for this is that if a control is partially obscured more work has to be done to redraw that area of the screen Unless you have the Smooth Updates preference on you will probably see more flicker when controls are overlapped As with other kinds of I O there is a certain amount of fixed overhead in the display of a control You can pass multiple points to an indicator at one time using some controls such as charts You can minimize the number of chart updates you need to make by passing more data to the chart each time You can see much higher data display rates if you collect your chart data into arrays so that you can display multiple points at a time instead of displaying each point as it comes in When you design subVIs whose front panels are closed during execution you do not need to worry about display overhead If the front National Instruments Corporation 26 7 G Programming Reference Manual Chapter 26 Performance Issues Other Issues panel is closed you do not have the drawing overhead for controls so graphs are no more expensive than arrays Parallel Diagrams When you have multiple diagrams running in parallel the execution system switches between them periodically If some of these loops are less important than others use the Wait function to ensure that the less important loops use less time For example consider the following di
219. array thus eliminating the need for you to wire to the count terminal explicitly If you start auto indexing for more than one tunnel or if you do set the count explicitly the count becomes the smallest of the choices So if two auto indexed arrays enter the loop with 10 and 20 components respectively and if you wire a value of 15 to the count terminal the count is 10 and the loop indexes only the first 10 components of the second array Auto indexing output arrays receive a new output element from every iteration of the loop Therefore auto indexed output arrays are always equal in size to the number of iterations 10 in the previous example If auto indexing is disabled only the value from the last iteration of the loop is passed G Programming Reference Manual 18 8 National Instruments Corporation Chapter 18 Structures Auto Indexing with While Loops When you begin auto indexing for an array entering a While Loop the While Loop indexes the array the same way as a For Loop does However the number of iterations a While Loop executes is not limited by the size of the array because the While Loop iterates as long as a certain condition is TRUE When a While Loop indexes past the end of the array the default value for the array element type passes into the loop Auto indexing output arrays receive an output element from each iteration of the While Loop They continue to grow in size as long as the While Loop executes i No
220. ary file with the 11b extension appears in the file dialog box Macintosh users using the native file dialog box need to press the Use LLBs button first before being able to select a VI library When you double click on the name of the library file or press Open the dialog box presents an option so you can save the file in the library Editing the Contents of Libraries You can remove a file from a VI library using the File Edit VI Library option With the Edit VI Library dialog box that appears you also can mark files as Top Level which has two uses First when you create an application using the application builder libraries the Top Level setting indicates which VIs are to open automatically when you run the application Second if you double click on a specific library from the file system on Windows or Macintosh or if you launch your G development environment with a library name specified on a command line under Windows or UNIX G opens all top level VIs automatically For more complex editing operations you can use the 1lbedit vi in the general examples llbedit directory This directory also contains several subVIs that can help you create your own tools for editing LLBs G Programming Reference Manual 2 30 National Instruments Corporation Chapter Building SubVls This chapter discusses the concept of hierarchical design in your G applications and explains two methods of creating subVIs The chapter also desc
221. assing the data to it to be printed out With this organization you have complete control over the appearance of the printout using G controls and tools to create very simple or complex printouts Enhancing Printouts Using transparency and the Color tool you can hide portions of controls that you do not want to be visible in your printouts For example you can use transparency to simplify the appearance of the edges of controls National Instruments Corporation 5 7 G Programming Reference Manual Chapter 5 Printing VIs Use graphical objects from the Decorations palette to highlight sections of your printout For example you might surround a section of controls with a box to set it off from the remainder of your panel You also can use bitmapped graphics to customize your printout adding elements such as company logos to your report Setting Page Layout The settings in Edit Preferences and in Printer Setup Page Setup for the Macintosh and UNIX affect the appearance of your printouts You also can use VI Setup Execution Options to implement or disable some layout options that affect the appearance of your printout These page layout options shown in the following illustration also affect the behavior of the Print Window O Print Panel when Vl Completes Execution Print Header name date page gt Scale to Fit Ee Surround Fanel with Border The Print Panel When VI Completes Execution option is
222. at generate data take care of allocating the storage for that data When data is no longer being used the associated memory is deallocated When you add new information to an array or a string enough memory is allocated automatically to manage the new information This automatic memory handling is one of the chief benefits of G However because it is automatic you have less control over when it happens If your program works with large sets of data it is important to have some understanding of when memory allocation takes place An understanding of the principles involved can result in programs with significantly smaller memory requirements Also an understanding of how to minimize memory usage can also help to increase VI execution speeds because memory allocation and copying data can take a considerable amount of time If you have a machine with a limited amount of memory you might want to consider using virtual memory to increase the amount of memory available for applications Virtual memory is a capability of your operating system by which it uses available disk space for RAM storage If you allocate a large amount of virtual memory applications perceive this as memory that is generally available for storage G Programming Reference Manual 26 12 National Instruments Corporation Chapter 26 Performance Issues For applications it does not matter if your memory is real RAM or virtual memory The operating system hides the fact tha
223. ata cluster of sods and array of cluster of Notice that the arrays are bundled into clusters using the Bundle function and the resulting clusters built into an array with the Build Array function You can use the Build Cluster Array which creates arrays of clusters of specified inputs instead The fifth data type is an array of clusters of an x value a Ax value and an array of y data This is the most general of the waveform graph multiplot data types because you can specify a unique starting point G Programming Reference Manual 15 8 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators and increment for the x axis of each plot The following diagram illustrates how you can create this kind of data array of cluster of xo dx and u Build array Waveform Graph XY Graph Data Types The XY graph accepts two multiplot data types as described in the following paragraphs Both of these data types are arrays of clusters of the single plot data types described previously The first data type is an array of clusters of plots where a plot is an array of points A point is defined as a cluster containing an x and y value The following diagram illustrates how you can create this kind of data National Instruments Corporation 15 9 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators array of cluster of array of cluster of x amp G Programming R
224. ata Range submenu of the Boolean pop up menu Boolean Data Range Checking You might want to detect errors in Boolean values If you expect a Boolean to always be TRUE you can select Data Range Suspend If False from the submenu of the Boolean pop up menu If you expect the Boolean to always be FALSE you can select Data Range Suspend If True to catch errors If the unexpected Boolean value occurs the VI suspends before or after it executes as described for the Suspend option of numeric range Configuring the Mechanical Action of Boolean Controls Boolean controls have six types of mechanical action Select the appropriate action for your application from the pop up menu Mechanical Action palette shown in the following illustration In these palette symbols M stands for the motion of the mouse button G Programming Reference Manual 10 4 National Instruments Corporation Chapter 10 Boolean Controls and Indicators when you operate the control V stands for the output value of the control and RD stands for the point in time that the VI reads the control Change to Indicator Find Terminal show Data Operations Create Key Navigation Replace Mechanical Action gt ie ee ee vJ p a A C a E m o a MF Oe Hye oD C g O jet a E kp t t ro tt rott The Switch When Pressed action changes the control value each time you click on it with the Operating tool in a manner similar to that of a Soe light swit
225. ate Indicator Data Operations P Replace a Size to Text Normal Display Y Codes Display Password Display Hex Display Limit to Single Line Create Constant Create Control Create Indicator You can use the arrow keys to increment or decrement a new numeric constant or one with its value selected This is particularly useful when programming control parameters with low values like 1 2 or 3 National Instruments Corporation 16 5 G Programming Reference Manual Chapter 16 Introduction to the Block Diagram The enumerated constant is similar to the ring constant except that the mnemonics strings associated with an integer value are considered part of the type When an enumeration is wired to the selection terminal of a Case Structure cases are named according to the mnemonics of the enumeration rather than traditional numeric values The numeric representation of an enumeration is always an unsigned byte word or long The ring constant associates text with a number the same way a ring control on the front panel does The value of the ring constant is an unsigned 16 bit integer Although you can change the representation of a ring constant to any numeric type except complex the value is still always an integer from zero ton 1 You can select colors from the color box constant to use with the color box control a control whose values correlate to specific colors Set the color box by clicking on it with the Co
226. ately e PostScript facilitates high resolution graphs e PostScript reproduces patterns and line styles more accurately You use the Preferences dialog box to indicate if you want to use PostScript printing If you select PostScript printing you have the option to select PostScript level 2 or Color Grayscale which supports color printing See Chapter 7 Customizing Your G Environment for information on the Preferences dialog box Printing the Active Window You can use the Print Window option to print out the contents of the currently active window front panel or block diagram Using this option you can make a quick printout with the minimum number of prompts For more comprehensive printouts of VIs use the Print Documentation menu option Print Window formats the printout so that it looks the same as it does when you set the VI to print programmatically The Execution Options section of the VI Setup dialog box contains a few options which give you more control over the way your VI looks when you print programmatically or when you print using Print Window See the Setting Page Layout section later in this chapter for information on these options G Programming Reference Manual 5 2 National Instruments Corporation Chapter 5 Printing VIs Selecting Print Options If you want a more detailed printout of the contents of a VI use the Print Documentation option shown in the following illustration This option
227. ation and you can click on the Run button to continue execution Run button Return to Caller button If the value of an indicator or control becomes invalid while a subVI is running execution pauses as if there were a breakpoint The front panel of the VI opens or becomes the active window The indicator s and control s that are currently invalid are outlined in red or a thick black line on a black and white monitor When a suspended VI finishes execution if there are any invalid values the Return to Caller button is disabled as shown in the following illustration You must set indicators to valid values before you can return to the calling VI You also can change the control values to produce valid outputs and run the subVI again by clicking on the Run button When G Programming Reference Manual 9 8 National Instruments Corporation Chapter 9 Numeric Controls and Indicators all indicator values are valid the toolbar looks like the following illustration and you can click on the Return to Caller button to continue execution Format and Precision of Digital Displays You can select the format of your digital displays for numerics or for time and date If numeric you can choose if the notation is floating point scientific engineering or relative time in seconds and you can select their precision that is how many digits to the right of the decimal point they display from 0 through 20 The precision you sele
228. ave to wait until Snooze woke up at noon which would be two hours late Using a Storage VI Not Meant to Share Its Data Another situation that requires reentrancy is when you make multiple calls to a subVI that stores data Suppose you create a subVI ExpAvg which calculates a running exponential average of four data points To remember the past values ExpAvg uses an uninitialized shift register with three left terminals If you are a LabVIEW user see Chapter 3 Loops and Charts of your LabVIEW Tutorial Manual for more information on uninitialized shift registers If you are a Bridge VIEW user refer to Chapter 10 Loops and Charts of the Bridge VIEW User Manual Next suppose you have a VI that uses ExpAvg to calculate the running average of two data acquisition channels For example you are monitoring the voltages at two points in a process and want to view the exponential running average on a strip chart The diagram contains two ExpAvg nodes The calls alternate one for Channel 0 then one for Channel 1 Assume Channel 0 executes first If ExpAvg is not reentrant the call for Channel 1 uses the average computed by the call for National Instruments Corporation 24 7 G Programming Reference Manual Chapter 24 Understanding the G Execution System Channel 0 and the call for Channel 0 uses the average computed by the call for Channel 1 By making ExpAvg reentrant each call can execute independently without danger of sharing
229. ay Cells ss ssesseesseesseeeeeeee 14 14 G Arrays and Arrays in Other SystemS eeeseeesseeesesreersresreresreerssrerrsessesrsse 14 16 CUUSTOIS iano ra oseas r A skesbeseaseea nesta E tines E EEr E EE E EE a 14 19 Creating Clusters neser eeso Ses each Se o es E E E Ee eed 14 20 Operating and Configuring Cluster Elements s sseseseeeesseeesesresrserserersrrerseees 14 20 Cluster Elements inoen e an uo nE E E EE E a cio 14 21 Cluster Default Values siisii air a rasar 14 21 Cluster Element Order 0 eee ceeseecseceseeseceseeseceseeseeseeesesenseseeeneeaes 14 21 Moving or Resizing Clusters tees ceseeeeceseeeeeeeeeeeeeeeeseeeneeaes 14 22 Cluster Assembly cocci eine oes E E o E suelo 14 23 Bundle PUN CHM sssini eisene ee i a 14 24 Bundle By Name Function ce eessceeeceeeeceseeceececeeeeneeeeeeesseeeeeeens 14 24 Array To Cluster Function isise iisisti isinsi rinos ni sieis oE 14 28 Cluster Disassemblyni os einen eee eree E r e E eel sine e Ta 14 29 Unbundle Function siessen a senses 14 29 Unbundle By Name Function ssssessseesseeesseeesesssserrrsrerrsreererenreresreersee 14 30 Cluster To Array FUn ction cece cee csesseceseeeceeceseeseeeseeseeeeeeeesenes 14 32 Replacing Cluster Elements 000 00 ee ecesceeeecseecsececeenecneceseeeceseeeeeeeeeeeseneesaeena 14 33 G Programming Reference Manual xii National Instruments Corporation Table of Contents Chapter 15 Graph and Chart Controls and Indicators Creatin
230. bdiagrams seesssesesseeessseeseeresesteserresrersreersrenterrneenerneeens 18 18 Adding S bdiagraM Sis sinsero sh sscetsessdss tessa ti aana ca sssdaa oskr EEEE aoao S Eoi pisike 18 19 Deleting Subdiagrams nenese seneseceeeseesnecsseesecesenssensesssonsesssonsesevenessee sees 18 20 Reordering Subdiagrams 00 0 eee eeeceeceeeeeseeeeeeseessecaecseaecseeseceeeeeseeeeeeseneeage 18 21 Structure Wiring Problems 0 eee ee eeeseeeeeceeeecaeceaeeeeceaeeeceeceeeseaeeeeseneeaee 18 22 Assigning More Than One Value to a Sequence Local 18 22 Failing to Wire a Tunnel in All Cases of a Case Structure 18 22 Overlapping Pummels siiin reia ri E i ee 18 23 Wiring from Multiple Frames of a Sequence Structure 18 24 Wiring underneath Rather than through a Structure 0 0 ee 18 25 Removing Structures without Deleting Items in a Structure 18 26 Chapter 19 Formula Nodes Using Formula Nodes 2 csccccecesiviecscassche eee sensi ene ndvebeye ERT aa i ae 19 2 Formula Node Functions and Operators sssseeseseeeesssresesrssrsrestrrtsrertsreeresreresrnserreseeerere 19 5 Formula Node Syntax ois ccisccsssvstssssasceesseasoes sas ioesbesspsdebsten dss ESTE ries Eies tk TSERE kao TREES 19 8 Formula Nod FITOLS iiei E E E E TEENE alee Ea TE iak 19 9 Chapter 20 Attribute Nodes Creating Attribute Nodes tinen sce e E er eee eee 20 1 Using Attrib te Node Hel pss cciicc orrcatarecsonteseousen cheers e n i 20 6 Base At
231. bit format signed or unsigned You can store arrays through the size of each dimension of any array in long integers followed by the data Because of alignment constraints of certain platforms the dimension size might be followed by a few bytes of padding so that the first element of the data is correctly aligned If you are a LabVIEW user see the Alignment Considerations section of Chapter 2 CIN Parameter Passing of the LabVIEW Code Interface Reference Manual for further information The example that follows shows a one dimensional array of single precision floating point National Instruments Corporation A 3 G Programming Reference Manual Appendix A Data Storage Formats numbers The decimal numbers to the left represent the offsets of locations in memory from which the array begins dimsize n O floai_3 0 floal_3z2 1 float_32 n 2 float_32 n 1 This illustration shows a four dimensional array of word integers O meen O O raams OO ee o 4th dimSize 1 menoon O meoo Int_1 i 1 j 1 k 1 1 2 Int_i id j 1 k 1 141 You store Boolean arrays differently from Boolean scalars An array of Booleans is stored as packed bits The dimension size for Boolean arrays is expressed in bits instead of bytes You store the Oth bit in the highest order bit of its memory word 2 gt and the 15th bit in the lowest order bit of its memory word 2 as shown in the following illustration G Pr
232. bute Node the Find Control and Find Terminal options of the terminal and control pop up menus change to submenus that help you find Attribute Nodes In the same way the Attribute Node has options to find the control and the terminal it is associated with See general attribute 11b for an example of how to use an Attribute Node Using Attribute Node Help The Help Window and Online Reference Help menu are invaluable tools for implementing Attribute Nodes You can use them to find descriptions data types and acceptable values for attributes For more information refer to the Attribute Node Help section in Chapter 1 Introduction to G Programming G Programming Reference Manual 20 6 National Instruments Corporation Chapter 20 Attribute Nodes Base Attributes There are many attributes available for modifying the various front panel objects in your application This section discusses Visible Disable Key Focus Blinking Position and Bounds attributes which are common to nearly all front panel objects Visible Attribute You can set or read the visibility of a front panel object with the Visible Attribute The associated object is visible when TRUE hidden when FALSE In the following illustration the digital control is set to an invisible state A Boolean TRUE value makes the control visible again as shown Block Diagram Front Panel digital contral Visible TRUE digital control
233. cDisk and TransferPro available for the PC that transfer Macintosh disks to the PC format and vice versa On the Macintosh DOS Mounter and Apple File Exchange are two utilities that convert files on DOS formatted disks to the Macintosh format and vice versa For the Sun and HP there is PC File System PCFS that helps SunOS and HP UX to read and write DOS formatted disks To ease porting between platforms you can save your VIs into a VI library To facilitate saving all your VIs into a library you can select the Development Distribution option from the Save with Options dialog box In this way you can save all non vi lib VIs controls and external subroutines to a single library G Programming Reference Manual B 6 National Instruments Corporation Appendix B Common Questions about G Printing When using automatic programmatic printing while executing a VI why is the information not printed until the VI stops executing Programmatic printing by design does not print a VI or subVI until it stops execution For printing during execution use a File Print Window to print the front panel manually or b a call to a subVI that accepts the input data to its controls the front panel might be identical to that of the executing VI and prints its results with programmatic printing For more details see the section Programmatic Printing in Chapter 5 Printing VIs How do I print a single control from the front panel for examp
234. cales to reflect the array of points you wire to them You can turn this G Programming Reference Manual 15 12 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators autoscaling feature on or off using the Autoscale X and Autoscale Y options from the Data Operations or the X Scale Y Scale submenus of the pop up menu for the graph You also can control these autoscaling features from the palette for the graph as described later in this chapter Autoscaling on is the default setting for graphs However autoscaling can cause the graph to run more slowly You can change the horizontal or vertical scale directly using the Operating or Labeling tool just as you can with any other control or indicator The graph point density is set automatically The Data Operations submenu of the graph pop up menu includes a Smooth Updates option that uses an offscreen buffer to minimize flashing This feature can cause the graph to run more slowly depending on the computer and video system you use The X and Y scales each have a submenu of options as shown in the following illustration Change to Control Find Terminal Show Data Operations P Create Kou Regine tip Replace H Scale s Marker Spacing gt Scale Hild Marker PRGEYEG Gap itea HEE ER pagida daa Bed aie ay Formatting lt AutoScale H Loose Fit Marker Spacing By default marker values for x and y scales are uniformly distributed
235. calling VI you manually have to find that directory only once for that load You also can remove a path using the Remove button which places the removed path into the string box in case you decide to re insert it elsewhere in the list cz Note Changes to the VI Search Path option take effect immediately Performance and Disk Preferences While it executes G maintains temporary files on disk For example when you save a VI G first saves it into a temporary file If the save is successful the original is replaced with the new file G needs a fair amount of disk space for these operations To avoid problems G normally checks for available disk space in the temporary directory at launch time If you have less than 500 KB of disk space free G alerts you and quits If you have less than 2 MB available G warns you but continues You can turn these warnings off or change the levels at which they alert you using the Performance and Disk dialog box accessed from the Preferences pull down menu G Programming Reference Manual 7 6 National Instruments Corporation Chapter 7 Customizing Your G Environment The Performance and Disk Preferences dialog box is shown in the following illustration Notice that one option is only available on Windows 3 1 and some other options are only available on the Macintosh Preferences Performance and Disk v C Deallocate memory as soon as possible C Use default timer Check available disk space
236. can use the Wait function to make less important tasks execute less frequently For example if you have several loops in parallel and you want some to execute more frequently put the Wait functions in the lower priority tasks This causes them to execute less frequently relinquishing more time to other tasks National Instruments Corporation 24 3 G Programming Reference Manual Chapter 24 Understanding the G Execution System In many cases doing this is sufficient You probably do not need to change the priorities using the VI Setup options VI Setup Priority Setting If you decide to use priorities and you do not want high priority VIs to push aside lower priority VIs make sure to put Wait functions in lower priority sections of the high priority VIs You change the priority of a VI using the Priority option in the VI Setup dialog box There are five levels of priority 0 1 2 3 and subroutine with 0 the lowest and subroutine the highest priority Higher priority VIs execute before lower priority VIs That is if the execution queue contains two VIs of each priority level the level 3 VIs share execution time exclusively until both of them finish Then the level 2 VIs share execution time exclusively until both of them finish and so on The exception to this occurs if the higher priority VIs call a Wait function or a Device I O function which are used by GPIB and Serial Port VIs In this case the higher priority VIs are
237. cators that simulate LEDs and lights are shown in the following illustration f L Clicking on a Boolean control with the Operating tool toggles it between its TRUE on and FALSE off states In run mode clicking on an indicator has no effect because indicators are for output only In edit mode you can operate both controls and indicators G Programming Reference Manual 10 2 National Instruments Corporation Chapter 10 Boolean Controls and Indicators Configuring Boolean Controls and Indicators Each Boolean control or indicator has several options available in its pop up menu The pop up menu for a Boolean object is shown in the following illustration Vertical Toggle Switch IF Change to Indicator Find Terminal Show Data Operations Create Key Navigation Replace Data Range Mechanical Action P The options above the dotted line in the pop up menu are common to all controls and indicators and are described in the Front Panel Control and Indicator Options section of Chapter 8 Introduction to Front Panel Objects The Data Range and Mechanical Action options are discussed later in this chapter Changing Boolean Labels Several controls in the Boolean palette display text and are called labeled Booleans Initially the buttons display the word ON in their TRUE state and the word OFF in their FALSE state as shown in the following illustration Then when you click on the button with the Ope
238. ced behind all s items compiled as subroutines and other priority 3 items A potential danger in using VI priority is that low priority items never execute if higher level tasks are always available to run Also priority does not indicate which of two items in parallel is executed first If something with high priority is put on the queue it executes as soon as the currently executing lower priority node checks the queue G Programming Reference Manual B 12 National Instruments Corporation Appendix B Common Questions about G How can G service interrupts without using polling Occurrences are a method for G to make a section of code wait for a particular event For example you can write a CIN that spawns a process in Windows through a DLL for example that generates an occurrence when an event takes place in the DLL A particular section of diagram code is executing and another section or VI is waiting for the event When the event happens it logs the occurrence in LabVIEW or Bridge VIEW and the appropriate code begins to execute as soon as its turn on the queue comes up Internally LabVIEW and Bridge VIEW look at the queue when it finishes a block of atomic code This means that if something else is executing it must complete before the occurrence and hence the interrupt is handled Note There is no definite time limit on how long this might be particularly if the VI contains CINs which may take a very long time to
239. cel The Options button brings up the following dialog box Conversion Options VWI Generation Options CJ Leave VI Front Panels Open EJ Create Library Call on Block Diagram EJ Assume 16 bit DLL INT type passed as INT16 EJ Add Instrument Error 170 Checking EJ Use Subil for Cv Error Conversion CJ Include C I Class Names in Vl Names O Use C Function Names for Wla EJ Convert All Control Names to Lowercase Eg Assign Instrument Driver loons Based on Name 2048 Default Size for Array Parameters The conversion options are as follows Leave VI Front Panels Open Causes the converter to leave VIs in memory with their front panels open when conversion is complete rather than disposing of each VI after it is saved to disk Off by default Create Library Call on Block Diagram Causes the converter to place a Call Library Function node on the block diagram of each VI G Programming Reference Manual 23 10 National Instruments Corporation National Instruments Corporation Chapter 23 Calling Code from Other Languages and wire up all front panel terminals appropriately If this option is not on only the front panel is created nothing is dropped on the block diagram On by default Assume 16 bit DLL Windows 3 1 Causes the converter to treat the Integer type from the LabWindows CVI function panel as an INT16 rather than an INT32 when creating the type descriptor describing the argument
240. ch The action is not affected by how often the VI reads the control mF The Switch When Released action changes the control value only after ur you release the mouse button during a mouse click within the graphical res boundary of the control The action is not affected by how often the VI reads the control a The Switch Until Released action changes the control value when you uP L click on it and retains the new value until you release the mouse button sade At this time the control reverts to its original value similar to the operation of a door buzzer The action is not affected by how often the VI reads the control mF With Latch When Pressed action the control changes its value when u TL you click on it and retains the new value until the VI reads it once At Fo tt this point the control reverts to its default value whether or not you keep pressing the mouse button This action is similar to that of a circuit breaker and is useful for stopping While Loops or for getting the VI to do something only once each time you set the control National Instruments Corporation 10 5 G Programming Reference Manual Chapter 10 Boolean Controls and Indicators The Latch When Released action changes the control value only after oa you release the mouse button within the controls graphical boundary ro tt When your VI reads it once the control reverts to the old value This guarantees at least one new value mF The Latch Until Rel
241. ch are available from the Controls Path amp Refnum palette shown in the following illustration d h d List HEE le b EA O Path amp Refnum D b la l la EO Los Path Controls and Indicators A path control and path indicator are shown in the following illustration Indicator National Instruments Corporation 12 1 G Programming Reference Manual Chapter 12 Path Controls and Indicators and Refnums Path Symbol Not a Path Symbol Refnums You can use path controls and indicators to enter and display respectively the location of a file or directory in a file system using the standard syntax for a given platform If a function that is supposed to return a path fails it returns an invalid path When an invalid path is displayed by a path control or indicator the Path symbol changes to the Not a Path symbol and lt Not A Path gt appears in the text field to indicate that the path is invalid You can change the value of a path control from a valid path to an invalid path by clicking on the Path symbol and selecting the Not a Path option from the menu This is shown in the following illustration In the same way you can change the value of a path control or indicator from an invalid path to a valid empty path by clicking on the Not a Path symbol and selecting the Valid Path option from the menu Nota Path agen 4 lt Not A Path gt You might use this Not a Path value as the default value
242. cimal Byte Integer 01 0004 xx01 Word Integer 02 0004 xx02 Long Integer 03 0004 xx03 Unsigned Byte Integer 05 0004 xx05 Unsigned Word Integer 06 0004 xx06 Unsigned Long Integer 07 0004 xx07 Single Precision 09 0004 xx09 Floating Point Number Double Precision OA 0004 xx0A Floating Point Number G Programming Reference Manual A 8 National Instruments Corporation Appendix A Table A 1 Scalar Numeric Data Types Continued Data Type Type Code Type Descriptor numbers in numbers in hexadecimal hexadecimal Extended Precision OB 0004 xx0B Floating Point Number Single Precision Complex 0C 0004 xx0C Floating Point Number Double Precision Complex OD 0004 xx0D Floating Point Number Extended Precision Complex OE 0004 xx0E Floating Point Number Enumerated Byte Integer 15 lt nn gt xx15 lt k gt lt k pstrs gt Enumerated Word Integer 16 lt nn gt xx16 lt k gt lt k pstrs gt Enumerated Long Integer 17 lt nn gt xx17 lt k gt lt k pstrs gt Single Precision Physical 19 lt nn gt xx19 lt k gt lt k base exp gt Quantity Double Precision Physical 1A lt nn gt xxlA lt k gt lt k base exp gt Quantity Extended Precision Physical 1B lt nn gt xx1B lt k gt lt k base exp gt Quantity Single Precision Complex 1C lt nn gt xx1C lt k gt lt k base exp gt Physical Quantity Double Precision Complex 1D lt nn gt xx1D lt k gt lt k base exp gt Physical Quan
243. continuously zooms out until you release the mouse button For the last two modes zoom in and zoom out about a point lt Shift gt clicking on zooms in the other direction Legend Options The graph uses a default style for each new plot unless you have created a custom plot style for it If you want a multiplot graph to use certain characteristics for specific plots for instance to make the third plot blue you can set these characteristics using the legend which can be shown or hidden using the Show submenu of the graph pop up menu You also can indicate a name for each plot using the legend National Instruments Corporation 15 19 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators When you select Legend only one plot appears You can create more plots by dragging down a corner of the legend with the Resizing tool After you set plot characteristics the graph assigns those characteristics to the plot regardless of if the legend is visible If the graph receives more plots than are defined in the legend the graph draws them in default style When you move the graph body the legend moves with it You can change the position of the legend relative to the graph by dragging the legend to a new location Resize the legend on the left to make more room on the labels or on the right to make more room on the plot samples By default each plot is labeled with a number beginning with zero You can
244. control or from the terminal of the control Find Terminal Show Data Operations Create Attribute Node Key Navigation Local Variable Replace Representation gt Data Range Format amp Precision Change to Indicator Hide Control Find Control Show Data Operations Cr Attribute E Local Variable Representation Create Constant Create Control Create Indicator National Instruments Corporation 20 1 G Programming Reference Manual Chapter 20 Attribute Nodes Selecting this option creates a new node on the diagram located near the terminal for the control as shown in the following illustration If the control has a label associated with it the label for the control is used for the initial label of the Attribute Node You can change the label after the node has been created temp terp DEE If you pop up on an attribute terminal and then choose Select Item you see a menu of attributes that you can set for or read from the control as shown in the following illustration You can use a shortcut to the list of attributes by clicking on the Attribute Node with the Operating tool Change All To Read Find gt Online Help Description Show Replace Change To Read Select ltem ag Visible Add Element Disabled Remove Element Key Focus Create Constant Blinking Create Control Position Create Indicator Bounds Show Full Names Text Width Format amp Precision Numeric Text Colors gt You ch
245. creen in black and white shades of gray or color depending on the capability of your monitor You can change the color of many G objects but not all of them For example block diagram terminals of front panel objects and wires use color codes for the type and representation of data they carry so you cannot change them You cannot change colors in black and white mode To change the color of an object or the background of a window pop up on it with the Color tool from the Tools palette as shown at the left The following palette appears in color LET ETT Te eae at Le ee LET TTT tet te ee E LT ttt yt yy E OOOOOOOOOOOOROoOo00000 aa Background More More All for both Other keys oe As you move through the palette while pressing the mouse button the object or background you are coloring redraws with the color the cursor currently is touching This gives you a preview of the object in the new color If you release the mouse button on a color the object retains the selected color To cancel the coloring operation move the cursor out of the palette before releasing the mouse button If you select the box with a T in it your application makes the object transparent With this feature you can layer objects For example you can place invisible controls on top of indicators or you can create numeric controls without the standard three dimensional container G Programming Reference Manual 2 24 Na
246. cription Replace Show Case Add Case After Add Case Before Duplicate Case Make This Case Remove Case National Instruments Corporation 18 21 G Programming Reference Manual Chapter 18 Structures Structure Wiring Problems The following sections discuss faulty connections with structures Assigning More Than One Value to a Sequence Local You can assign a value to the local variable of a Sequence Structure in only one frame although you can use the value in all subsequent frames The illustration to the left below shows the value pi assigned to the sequence local in frame 0 If you try to assign another value to this same local variable in frame 1 you produce a bad wire This error is a variation of the multiple sources error Failing to Wire a Tunnel in All Cases of a Case Structure Wiring from a Case Structure to an object outside the structure results in a bad tunnel if you do not connect a source in all cases to the object as shown in part 1 of the following example This is a variation of the no source error because at least one case does not show a data value if it executed Wiring to the tunnel in all cases as shown in part 2 of this example corrects the problem This is not a multiple sources violation because only one case executes and produces only one output value per execution of the Case Structure G Programming Reference Manual 18 22 National Instruments Corporation Chapter 18 Structures
247. ct affects only the display of the value the internal accuracy still depends on the representation To change any of these parameters of the digital display select Format amp Precision option from the display pop up menu The dialog box opens in numeric format as shown in the following illustration Format amp Precision Format Example Digits of Precision Floating Point Notation Scientific Notation Engineering Notation Relative Time seconds National Instruments Corporation 9 9 G Programming Reference Manual Chapter 9 Numeric Controls and Indicators You can see an example at the top of the dialog box as you make selections Examples of format and precision settings on a digital control are shown in the following illustration Ales 7123 floating point notation 4 digits of precision 6o 710E 0 engineering notation mile 571251640 scientific notation 6 digits of precision relative time 3 digits of precision seconds To format absolute time and or date select Time amp Date from the Format ring at the top of the dialog box The dialog box changes as shown in the following illustration Format amp Precision Example 06 23 39 PM 02717 1995 Format Time t Date w x Time AM PM O HH MM D 24 hour HH MM SS Seconds Precision og Don t Show Year 2 Digit Year 4 Digit Year Cancel MDY O D M Y Dymo You can format for either ti
248. cting Broken VI Range Errors 00 0 0 eee ceeesceceseeeeceeeeeeceseeeeecneeseeeaeenaes 4 14 Debugging Executable VIs oe ec ceeeecseessecneceseeeceseeseceseeseseeeeeeseaeeaeeeaeeaee 4 15 Recognizing Undefined Data eee ceeceseeseceseeeeeeeeeeeseeeeeeeens 4 17 Understanding Warning 0 eee cseceseeseceseeseceseeseeeeeeeeeeaeeseeeaeeaes 4 18 Debugging Feature seccsnciscessssissnsessctassctesstsaevencbvechegep ri r er EEEE E ERES 4 18 Single Stepping through VIS oo eee eee ceeeeeeeeeeeseecneesaecaeenaeenees 4 18 An Example of Single Stepping through a VI 4 19 Using Step Buttons seis ccocseveutcisncestelaees Seabee csaened oes csacnentebnaseneveoes 4 20 Reading Call Chains i csscosscscss sseedarseessettactseseabasaapiaseshsvsgebsseseneseesees 4 21 Execution Highlighting ce escescecsseeesceeeeeesseceseeceeeenaeeeeeeseeeeeeens 4 21 Using the Probe Tool sc os scis esccc sesh ch es sceehcsscnas ced ssedess above icaeassseescbnees 4 23 Creating Probes oono ee en dd asians actin ies 4 25 Placing Breakpoint Tools 0 0 0 eee ceceseeseceseeseceseeseeeeeeeeeeaeeseeeaeenee 4 26 Suspending Execution eee cece ceseeeeceeeeeeceseeeeeeneeseecseesaecseesaeenees 4 29 Recognizing Automatic Suspension cee eeeeeeeeeeeee 4 29 Using Toolbar Buttons When SubVIs Are Suspended 4 30 Viewing Hierarchy Windows During Suspension 4 30 Disabling Debugging Features 20 0 cesceseeeeceeeeeeeeneeeneenes 4 31 Commenting out S
249. ctions for subVIs connectors accessing 1 6 overview 1 6 terminal patterns for subVIs See also terminal connections for subVIs changing spatial arrangement 3 6 defining 3 5 selecting and modifying 3 6 National Instruments Corporation constants 16 3 to 16 8 creating automatically 16 13 definition 16 3 pop up menus 16 5 representation 16 7 resizing 16 7 universal string constants 16 7 definition 16 3 numeric constants 16 7 user defined 16 3 to 16 7 availability in palettes 16 3 to 16 4 color box constant 16 6 creating 16 3 to 16 4 enumerated constants 16 6 error ring 16 6 to 16 7 incrementing and decrementing 16 5 list box symbol ring 16 6 numeric constant pop up menu 16 5 numeric constants 16 4 path constant 16 7 ring constants 16 6 setting values 16 4 string 16 4 string constant pop up menu 16 5 Control Editor illustration 22 2 opening with double click 7 9 Parts window 22 7 to 22 9 purpose and use 22 1 to 22 3 Index controls and indicators See also specific types assigning terminals 3 6 to 3 8 changing indicators to controls 17 13 controls as parts 22 15 to 22 17 creating automatically 16 13 customizing dialog box controls 8 9 to 8 10 front panel control and indicator pop up menu options 8 2 to 8 4 Change to Control 8 3 Change to Indicator 8 3 Create Attribute Node 8 3 Data Operations submenu 8 3 Find Terminal 8 3 Key Navigation 8 5 to 8 8 pop up menu
250. ctures without Deleting Items in a Structure You can remove a structure For Loop While Loop Case Structure or Sequence Structure without losing the contents of the structure If you pop up on any of these objects you see an option for deleting the structure In the case of For Loops and While Loops the contents of the loop are copied to the underlying diagram In addition any wires that were connected by tunnels are connected together automatically In the case of a Case Structure or Sequence Structure removing the structure only preserves the current frame or case All other frames or cases are deleted and you are warned that you will lose hidden frames or cases and are given a chance to cancel the operation G Programming Reference Manual 18 26 National Instruments Corporation Chapter Formula Nodes This chapter describes how to use the Formula Node to execute mathematical formulas on the block diagram The Formula Node is a E available from Functions Structures Functions x Ga Gl Structures Formula Node ia National Instruments Corporation 19 1 G Programming Reference Manual Chapter 19 Formula Nodes Using Formula Nodes The Formula Node is a resizable box similar to the four structures For Loop While Loop Case Structure and Sequence Structure Instead of containing a subdiagram however the Formula Node contains one or more formula statements delimited by a semicolon as in
251. d with the exception of characters created with special keys such as the lt Tab gt or lt Esc gt key which are nondisplayable Backslash Codes Display Option By choosing the option Codes Display from the string pop up menu you instruct G to interpret characters immediately following a National Instruments Corporation 11 3 G Programming Reference Manual Chapter 11 String Controls and Indicators backslash as a code for nondisplayable characters The following table shows how G interprets these codes Table 11 1 G Codes Code G Interpretation 00 FF Hex value of an 8 bit character must be uppercase b Backspace ASCII BS equivalent to 08 Form feed ASCII FF equivalent to OC n Linefeed ASCII LF equivalent to OA Carriage return ASCII CR equivalent to OD t Tab ASCII HT equivalent to 09 s Space equivalent 20 Backslash ASCII equivalent to 5C Use uppercase letters for hexadecimal characters and lowercase letters for the special characters such as form feed and backspace Thus G interprets the sequence BFare as hex BF followed by the word are whereas G interprets bFare and bfare as a backspace followed by the words Fare and fare In the sequence Bfare B is not the backspace code and Bf is not a valid hex code In a case like this when a backslash is followed by only part of a valid hex character G assumes a
252. d SubVIs You can cut copy or paste the contents of the control set the control to its default value and read the description of the control with options in this menu Some of the more complex controls have additional options For example an array has options you can use to copy a range of values or go to the last element of the array Reinitialize to Default Cut Data Copy Data Pesia aia Description Epiipp Heir When editing a VI the pop up menu of an object contains an editing menu and a Data Operations submenu as shown in the following illustration This submenu contains the same options you see when National Instruments Corporation 4 3 G Programming Reference Manual Chapter 4 Executing and Debugging VIs and SubVIs running a VI plus an additional option the Make Current Value Default option SIn ran Se nd Change to Indicator Find Terminal Show Data Operations Reinitialize to Default Create Make Current Value Default Key Navigation Cut Data Replace Copy Data Paste Data Representation Description Data Range Online Help Format amp Precision The Operate menu on the menu bar contains commands for executing the current VI The following sections discuss several fundamental execution related tasks Stopping Vis Normally you should let the VI run until it completes However if you need to halt execution immediately click on the Stop button or select Operate Stop The S
253. d by one 20 array of y rows are graphs If you select the Transpose Array option from the graph pop up menu each column of data is handled as a plot This is particularly useful when sampling multiple channels from a data acquisition board because that data is returned as 2D arrays with each channel stored as a separate column The following example shows how you use a graph to display two signals where each signal is a separate row of a two dimensional array READ SIGMAL ce waveform Graph READ SIGMAL Arg The second data type is a cluster of an x value a Ax value and a two dimensional array of y data The y data is interpreted as described for the previous data type This data type is useful for displaying National Instruments Corporation 15 5 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators multiple signals that were all sampled at the same regular rate The following diagram illustrates how you can create this kind of data cluster of xo de and 2D array of Waveform Graph o_o The third data type is an array of clusters of an array of y data The graph interprets this data as points with the points starting at x 0 and incremented by one array of cluster of Use this data structure instead of a two dimensional array if the number of elements in each plot is different For example if you need to sample data from several channels but not for the same
254. d or suspended For more information about the Hierarchy Window see the Using the Hierarchy Window section of Chapter 3 Building SubVIs The arrow in the following illustration indicates a subVI that is running regularly or single stepping The pause glyph indicates a subVI that is paused and or suspended A green pause glyph or a hollow glyph if displayed in black and white indicates that this subVI pauses when called A red pause glyph or a solid glyph if displayed in black and white indicates that this subVI currently is paused Fibini paused Hierarchy Window Using the Probe Tool You can use the Probe tool to check intermediate values in a VI that executes but produces questionable or unexpected results For example you might have a complicated block diagram with a series of operations any one of which might be returning incorrect data One way to look for the source of the questionable results is to wire an indicator to the output wire from one of the operations to display the intermediate results But placing an indicator on the front panel and wiring its terminal to the block diagram is not a convenient debugging mechanism It is time consuming and creates unwanted items on your front panel and block diagram that you later must delete Probe tool selected National Instruments Corporation 4 23 G Programming Reference Manual Chapter 4 Executing and Debugging VIs and SubVIs Select the Probe tool and place its c
255. datalogging See data logging on front panel date formatting absolute digital displays 9 10 to 9 11 graph indicators 15 16 to 15 17 date preferences See Time and Date Preferences dialog box debugging commenting out sections of diagrams 4 31 disabling debugging features 4 31 execution highlighting 4 21 to 4 23 placing breakpoints 4 26 to 4 29 Breakpoint tool 4 26 Clear Breakpoint cursor 4 26 display of breakpoints table 4 27 example 4 28 to 4 29 setting breakpoint 4 27 Probe tool creating probes 4 25 to 4 26 using 4 23 to 4 25 reading call chains 4 21 suspending execution 4 29 to 4 30 options 4 29 recognizing automatic suspension 4 29 to 4 30 Return to caller button 4 30 Run button 4 30 Skip to beginning button 4 30 using toolbar buttons during suspension 4 30 viewing Hierarchy windows during suspension 4 30 National Instruments Corporation Debugging Preferences dialog box 7 12 to 7 13 Auto probe during execution highlighting 7 12 Show data bubbles during execution highlighting 7 12 Show warnings in error box by default 7 12 Warn about objects unavailable in student edition 7 12 debugging VIs 4 10 to 4 31 broken VIs common reasons for broken VIs 4 11 correcting broken VI range errors 4 14 to 4 15 error messages table 4 11 to 4 14 fixing broken VIs 4 10 to 4 11 locating errors 4 10 executable VIs 4 15 to 4 18 problem solving steps 4 15 to 4 17 recognizing undefined data 4 1
256. de scale pop up menu 9 14 marquee 2 7 Mechanical Action palette 10 4 to 10 5 memory preferences See Performance and Disk Preferences dialog box National Instruments Corporation memory usage 26 12 to 26 36 basic concepts 26 12 consistent data types 26 22 to 26 28 building arrays example 26 24 to 26 26 searching through strings example 26 27 to 26 28 dataflow programming and data buffers 26 14 to 26 17 deallocation 26 21 to 26 22 front panels 26 19 to 26 20 general rules for improving 26 18 to 26 19 global variables 26 21 input buffer reuse by output 26 22 local variables 26 20 to 26 21 Macintosh memory 26 13 monitoring 26 17 to 26 18 overview 26 12 questions about B 4 to B 5 showing 2 27 subVI reuse of data memory 26 20 VI components 26 13 to 26 14 virtual memory 26 12 to 26 13 menu bar definition 2 6 hiding 6 6 B 15 menu setup ring 7 26 menus color settings 7 13 to 7 14 hot menus 7 23 pop up menus 2 6 pull down menus 2 6 using 2 6 lt meta gt key bringing subVI block diagram to front 4 21 changing Icon Editor tools to dropper 3 4 cloning Attribute Nodes 20 4 cloning objects 2 13 creating new scale marker 9 17 to 9 18 cutting copying and pasting icons note 3 4 National Instruments Corporation 1 39 Index moving between array elements 14 13 moving between cluster elements 14 21 Step Into button shortcut 4 20 Step Out button shortcut 4 20 Step Over button sh
257. decimal digital control octal F d 3275Z aftr red digital control hexadecimal digital control binar x TFF bi111111111110001 Changing the Representation of Numeric Values You can choose from 12 representations for a digital numeric control or indicator Use the Representation option from the control or indicator pop up menu to change to 32 bit single precision SGL 64 bit double precision DBL extended precision EXT floating point numbers or one of the six integer representations signed 18 or unsigned U8 byte 8 bit signed 116 or unsigned U16 word 16 bit or signed 132 or unsigned U32 long 32 bit integers You also can choose complex extended precision CXT complex double precision CDB or G Programming Reference Manual 9 4 National Instruments Corporation complex single precision CSG floating point numbers These choices Chapter 9 are shown in the following illustration National Instruments Corporation Change to Indicator Find Terminal Show gt Data Operations gt Create gt Key Navigation Replace Representation d Data Range Format amp Precision m p m CXT CDB CSG E E 9 5 G Programming Reference Manual Numeric Controls and Indicators Chapter 9 Numeric Controls and Indicators Range Options of Numeric Controls and Indicators Each representation has natural minimum and maximum range limits For example signed byt
258. ded objects Selecting Change To Control or Change To Indicator from the pop up menu of any cluster element changes the cluster and all its elements from indicators to controls or from controls to indicators Operating and Configuring Cluster Elements With the exception of setting default values and the Change to Control and Change To Indicator options you configure controls and G Programming Reference Manual 14 20 National Instruments Corporation Chapter 14 Array and Cluster Controls and Indicators indicators the same way you configure controls and indicators that are not in a cluster Cluster Elements When in run mode you can use the lt Tab gt key either to move the key focus between front panel controls or between elements within a single cluster Initially the lt Tab gt key moves the key focus between front panel controls To have it move between the elements within a specific cluster first lt Tab gt to that cluster Then use the lt Ctr1 gt Windows lt command gt Macintosh lt met a gt Sun or lt Alt gt HP UX key and the down arrow which you can use you to move between the cluster elements If you want to return to tabbing between controls use the lt Ctrl gt Windows lt command gt Macintosh lt met a gt Sun or lt Al1t gt HP UX key and the up arrow Cluster Default Values To set the default value of the entire cluster to the current value of each individual element pop up on the fra
259. des If a focus node exists the window is scrolled to make that node visible If no focus node exists the window is scrolled to make the first root showing subVIs visible Show All VIs Displays all hidden VIs There is no focus node after this option has been selected The option does not affect other settings in the View menu In other words VIs in vi Lib global variables and type definitions that are not included in the hierarchy still are hidden Vertical Hierarchy Arranges the nodes from top to bottom with the calling VIs above their subVIs Horizontal Hierarchy Arranges the nodes from left to right with the calling VIs to the left of their subVIs Include VIs in vi l1ib Toggles the Hierarchy window to include or exclude VIs in vi lib Include Globals Toggles the Hierarchy window to include or exclude globals 3 18 National Instruments Corporation Chapter 3 Building SubVis e Include Type Defs Toggles the Hierarchy window to include or exclude type definitions e Full VI Path in Label Toggles the Hierarchy window to display either the full VI path or simply the name of the VI in the Tip strip for each hierarchy node Hierarchy Toolbar Buttons A toolbar in the Hierarchy window contains buttons that affect the display of the window The buttons which perform some of the same actions as items in the View menu are described as follows Redo Layout Redraws the window layout to minimize line crossi
260. development system because the other development system has its own vi lib Application Distribution Saves all VIs controls and external subroutines including the ones in vi 1ib to a single location and removes the diagrams from all of the VIs If you want to create a run time application that has an embedded library you can use this option to create the library to embed To actually create a run time application you need the Application Builder libraries which are sold separately Custom Save Selects the specific options you want from the Selected Options area of the dialog box if none of the predefined options fit your needs 25 4 National Instruments Corporation Chapter 25 Managing Your Applications Designing Applications with Multiple Developers If you have multiple developers working on the same project you need to spend some design time defining responsibilities to ensure that the project works well Start by considering the top level design of your application and create an outline You should create stub VIs for the major components of your application A stub VI is a prototype of a subVI It has inputs and outputs but is incomplete It serves as a place holder for future VI development at which time you add functionality Creating stub VIs for LabVIEW users is described in Chapter 10 Program Design in your LabVIEW Tutorial Manual Bridge VIEW users should refer to Chapter 15 Program Design of your BridgeVI
261. dicators bottom left terminal and the array element value is wired to the right terminal The following example shows the fundamental operation of replacing an array element The fragment of FORTRAN code generates a histogram of random numbers the random number generator produces values between 0 and 1 and so does the G version You can disregard the 1 in the FORTRAN computation of J the addition is needed because FORTRAN arrays are one based DO 10 I 1 10000 100 0 RAND 1 H J 1 10 CONTINUE G Direct Translation The indexing operation for inserting or replacing an element is represented in FORTRAN by parentheses on the left side of the equal sign following the array name and enclosing the index In G this operation is represented by the Replace Array Element function icon shown at left The array is wired to the top left terminal the replacement value is wired to the middle left terminal the index is wired to the bottom left terminal and the updated array is wired from Replace Array the right terminal Element function r f Before you can use an array in most programming languages you first must declare it and in some cases initialize it In G building an array control or indicator on the front panel is equivalent to declaring an G Programming Reference Manual 14 18 National Instruments Corporation Chapter 14 Array and Cluster Controls and Indicators array Defining a default value fo
262. displays a dialog box you can use to select from several VI formats You also can create your own custom format Print Documentation Select a format Icon Description Panel and Diagram oO y Complete Documentation Using the Panel Using as a Sub Layout Options E Seale Front Panel to Fit Ee Print Header name date page EJ Scale Block Diagram to Fit O Fage Breaks between Sections rm Prene Save Text Info Setting Printout Formats The Print Documentation dialog box has five different print formats The icon for each of these formats is shown to the left of the description The Icon Description Panel and Diagram format the default prints the icon VI description front panel and block diagram The Using the Panel format prints the front panel VI description and the control names and their descriptions The Using as a SubVI format prints the icon connector VI description and the terminals data types names and descriptions of the connected controls This format is similar to the G function reference format National Instruments Corporation 5 3 G Programming Reference Manual Chapter 5 Printing VIs Te The Complete Documentation format prints everything including the icon connector description front panel information about all front panel controls the block diagram and a list of the names of the subVIs The Custom format prints using the current custom settings
263. dows to ms If you increase the timer resolution your software timing loops are more accurate Under certain circumstances you might not want to increase the timer resolution from 55 ms Changing the resolution increases the number of timer tick interrupts from 18 interrupts per second to 1000 interrupts per second If you are performing other interrupt intensive operations you might exceed the capacity of your PC to handle the interrupt load which might lock up or crash your PC DAQ operations that use programmed I O instead of DMA to transfer data between the DAQ board and PC memory are interrupt intensive Do not change the timer tick resolution to 1 ms if you plan to perform any of the following operations at high transfer rates e Buffered analog input using the PC LPM 16 e Buffered analog output using the AT MIO 16 MC MIO 16 or Lab series boards e Buffered digital I O using the DIO 24 DIO 96 or Lab series boards e Buffered analog input or output with DMA disabled in WOAQCONF using any DAQ board Transfer rates of approximately 30 ksamples sec or higher on a 386 25 MHz machine causes interrupt load problems with the 1 ms timer resolution Transfer rates of approximately 75 to 80 ksamples sec or higher on a 486 33 MHz machine or 100 ksamples sec or higher on a 486 50 MHz machine might cause interrupt load problems The timing functions in G for Windows 95 NT have a timer resolution of 1 ms the maximum resolution possibl
264. during the change intermediate values might pass to the program depending on how often the VI reads the control You also can click on a point on the housing and the slider snaps to that location as shown in the following illustration Intermediate values do not pass to the program OH I ON io ee a eee o 00 5 00 1 o 00 0 00 5 bo o oo If you use a slide that has increment buttons you can click on an increment button as shown in the following illustration and the slider moves slowly in the direction of the arrow Hold down the lt Shift gt key to move the slider faster Intermediate values might pass to the program Just like the digital numerics slides have Representation Data Range and Format amp Precision options in their pop up menus These options work the same as they do for digital displays except that National Instruments Corporation 9 13 G Programming Reference Manual Chapter 9 Numeric Controls and Indicators Slide Scale G Programming Reference Manual slides cannot represent complex numbers Slides also have other options The following illustration shows a slide pop up menu Change to Control Find Terminal Show b Data Operations d Create Attribute Node kou Menippe tip Replace Representation Data Range Format Precision Add Slider Fill Options Text Labels The Show Digital Display option of the pop up menu controls the visibility of the digital display of the slide
265. e Distributing Vis When you are ready to distribute your VIs consider whether you want to distribute the VIs with or without the block diagrams Using the Save with Options dialog box you can remove diagrams from your VIs If you save your VIs without a diagram the VI cannot be modified by other users If you save your VIs without diagrams be careful not to overwrite your original versions iz Note VIs without diagrams cannot be converted to future versions of the application or to other platforms During conversion you need to recompile your VIs Without a block diagram a VI cannot be recompiled You also should consider what environment users need to use to run your VIs Do you want end users to have a development system or a run time application A run time application is appropriate when you do not expect your users to make modifications to your VIs A run time application contains simplified menus and users cannot edit VIs or view block diagrams G Programming Reference Manual 25 2 National Instruments Corporation Chapter 25 Managing Your Applications Run time applications are built using the LabVIEW Application Builder libraries When you build a run time application with these libraries you must answer these three questions e Do I want to embed a VI library in the application e DoI want the application to have an Open menu item e DoI want the application to have a Quit menu item If you choose to embed a
266. e 23 3 AESend Print Document VI 5 1 aligning objects 2 11 to 2 12 Bottom Edges 2 12 example 2 11 Horizontal Centers 2 12 National Instruments Corporation Left Edges 2 12 Right Edges 2 12 Top Edges 2 12 Vertical Centers 2 12 All Elements option 20 5 Allow Drag option 15 36 Allow Run Time Pop Up Menu option 6 5 Allow User to Close Window option 6 5 lt Alt gt key bringing subVI block diagram to front 4 21 changing Icon Editor tools to dropper 3 4 cloning Attribute Nodes 20 4 cloning objects 2 13 creating new scale marker 9 17 to 9 18 cutting copying and pasting icons note 3 4 moving between array elements 14 13 moving between cluster elements 14 21 Step Into button shortcut 4 20 Step Out button shortcut 4 20 Step Over button shortcut 4 20 lt Alt b gt removing bad wires 4 10 lt Alt click gt copying and transferring colors 2 26 executing Show VI Hierarchy action 3 21 untacking last tack point note 17 3 lt Alt f gt bringing up Find dialog box 3 24 lt Alt h gt help key 1 7 lt Alt m gt switching from run mode to edit mode note 6 6 lt Alt Return gt embedding newlines 7 10 lt Alt Shift gt bringing up temporary Tools palette 2 4 Apple Event VIs executing other applications from within VIs 23 1 G Programming Reference Manual Index AppleEvent option Communications menu 5 1 Application Distribution option 25 4 Application font 2 18 applications managing
267. e connector terminals act like parameters Each terminal corresponds to a particular control or indicator on the front panel A connector receives data at its input terminals and passes the data to the subVI code through the subVI controls or receives the results at its output terminals from the subVI indicators Every VI has a default icon which is displayed in the icon pane in the upper right corner of the front panel and block diagram windows This VI icon is shown in the following illustration Untitled 3 Diagram Cema Vee Every VI also has a connector which you access by choosing Show Connector from the icon pane pop up menu on the front panel When you bring up the connector for the first time you see a connector pattern You can select a different pattern if you want The connector generally has one terminal for each control or indicator on the front panel You can assign up to 28 terminals If you anticipate future changes to the VI that would require a new input or output leave some extra terminals unconnected With the extra terminals any new inputs or outputs will not affect other VIs that use this VI as a subVI For more information see Chapter 3 Building SubVIs G Programming Reference Manual 1 6 National Instruments Corporation Chapter 1 Introduction to G Programming Help in G The G Help window contains help information for functions constants subVIs controls and indicators
268. e Info Color Array attribute This attribute consists of an array of clusters in which each cluster contains a numeric limit value along with the corresponding color to display for that value When you specify the color table in this manner you can specify an upper out of range color using the Z Scale Info High Color attribute and a lower out of range color using the Z Scale Info Low Color The total number of colors is limited to 254 colors with the lower and upper out of range colors bringing the total to 256 colors If you specify more colors then the 254 color table is created by interpolating between the specified colors Another way to set the colors programmatically is to specify a color table using the Color Table attribute With this method you can specify an array of up to 256 colors Data passed to the chart is mapped to indices in this color table based upon the color scale If the color scale ranges from zero to 100 a value of zero in the data is mapped to index G Programming Reference Manual 15 40 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators one and a value of 100 is mapped to index 254 with interior values interpolated between one and 254 Anything below zero is mapped to the out of range below color index zero and anything above 100 is mapped to the out of range above color index 255 Note The colors you want your intensity chart or graph to display are limited to t
269. e Structure Show Case Add Case After Add Case Before Duplicate Case Make This Case Remove Case National Instruments Corporation 18 19 G Programming Reference Manual Chapter 18 Structures If you select Duplicate Case from either the structure border pop up menu or the diagram identifier pop up menu as shown below a copy of the visible subdiagram is inserted after itself Show d Description Replace d Remove Case Structure Show Case Add Case After Add Case Before Duplicate Case Make This Case Remove Case When you add or remove subdiagrams the editor automatically adjusts the diagram identifiers to accommodate the inserted or deleted subdiagrams Deleting Subdiagrams To delete the visible subdiagram choose Remove Case from the structure border pop up menu shown below The values of higher numbered subdiagrams adjust automatically This command is not available if only one subdiagram exists G Programming Reference Manual 18 20 National Instruments Corporation Chapter 18 Structures Show Description Replace Show Case Add Case After Add Case Before Duplicate Case Make This Case Remove Case Reordering Subdiagrams To move a subdiagram to another location select Make This Case from the structure border pop up menu as shown below and choose a new value from the hierarchical menu that appears The editor automatically adjusts the diagram identifiers of other subdiagrams Show Des
270. e Y Update Mode The three options strip chart scope chart and sweep chart are illustrated in the following pictures and described in the subsequent paragraphs The default mode is strip chart G Programming Reference Manual 15 26 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators The strip chart mode has a scrolling display similar to a paper tape strip chart recorder As each new value is received it is plotted at the right margin and old values shift to the left Strip Chart The scope chart mode has a retracing display similar to an oscilloscope As each new value is received it is plotted to the right of the last value When the plot reaches the right border of the plotting area the plot is erased and plotting begins again from the left border The scope chart is significantly faster than the strip chart because it is free of the processing overhead involved in scrolling Scope Chart The sweep chart mode acts much like the scope chart but it does not blank when the data hits the right border Instead a moving vertical line marks the beginning of new data and moves across the display as new data is added National Instruments Corporation 15 27 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators Sweep Chart Stacked Versus Overlaid Plots By default the chart displays multiple plots by overlaying one on top of the other like graph
271. e available in For Loops and While Loops are local variables that feed back or transfer values from the completion of one iteration to the beginning of the next By selecting Add Shift Register from the loop border pop up menu you can create a register anywhere along the vertical boundary as shown in the following illustration This menu item is not available from the top or bottom edge of the structure You can reposition a shift register along the vertical boundary by dragging it Online Help Description Show Replace Remove For Loop Add Shift Register A shift register has a pair of terminals directly opposite each other on the vertical sides of the loop border The right terminal the rectangle with the up arrow stores the data at the completion of an iteration G shifts that data at the end of the iteration and it appears in the left terminal the rectangle with the down arrow in time for the next iteration You can use shift registers for any type of data but the data you wire to the terminals of each registers must be of the same type You can create multiple shift registers on a particular structure To initialize a shift register wire a value from outside the loop to the left terminal If you do not initialize the register the loop uses as the initial value the last value inserted in the register when the loop last executed or the default value for its data type if the loop has never before executed Use initialized s
272. e becomes a front panel terminal and the rest remain as local variables in the subVI Only one instance of the local variable is retained on the caller VI the rest of the selected instances are removed from the caller and moved to the subVI e Because local variables can either read or write from a front panel terminal when instances of both read and write local variables are selected two front panel objects are created in the subVI one to pass the value of the local variable into the subVI and another to pass the value out of the subVI The front panel terminal created to represent the read local variables has the suffix read added to its name and the front panel terminal created to represent the write locals has the suffix write added to its name Note Currently there is no Undo option to undo the creation of a subVI However selecting File Revert can undo the creation of a subVI by reverting to the VI as it existed before the last save that you have made Rules and Recommendations The ability to create a subVI from a selection can be a great convenience but might not be as simple as it seems Careful planning still is required to create a logical hierarchy of VIs Moreover you must consider which objects should be included in the selection so that you can avoid situations where the functionality of a resulting VI is affected adversely In cases where a problem definitely occurs G does not make a subVI out of the select
273. e elements than the cluster the function ignores the remaining elements If the array contains fewer elements than the cluster the function assigns the extra cluster elements the default value for the element data type The illustration that follows shows how to display an array of data in a front panel cluster indicator With this technique you can organize the array elements on the front panel to suit your application You might use a tabular array indicator instead but that limits you to a fixed display format horizontal with the lowest element at left and an attached index display G Programming Reference Manual 14 28 National Instruments Corporation Chapter 14 Array and Cluster Controls and Indicators Cluster Disassembly FH Unbundle function G has three functions for disassembling clusters The Unbundle and Unbundle By Name functions disassemble a cluster into individual elements and the Cluster To Array function converts a cluster of identically typed elements into an array of elements of that type Unbundle Function The Unbundle function which you obtain from the Array amp Cluster palette of the Functions palette has two element output terminals on the right side You adjust the number of terminals with the Resizing tool the same way you adjust the Bundle function Element 0 in the cluster order passes to the top output terminal element passes to the second terminal and so on The cluster wire remains bro
274. e illustrations of a waveform graph and an intensity graph with the Cursor palette displayed euro leoo eoo lee HHE kwi Foo IFoo ea HHA Intensity Graph National Instruments Corporation 15 31 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators Each cursor for a graph has the following parts e A label e Xand Y coordinates and Z coordinate if applicable e A button that marks the plot for movement with the plot cursor pad e A button that controls the look of the cursor e A button that determines if the cursor is locked to a plot or can be moved freely These parts are shown in the following illustration Cursor movement control oS Select button for cursor movement Cursor name Y position Cursor display X position Z position xK control Lock ro Jeo em eo EA A The Cursor palette behaves like an array You can stretch it to display multiple cursors and you can use the index control to view other cursors in the palette Use the Show options on the pop up menu to display the index control G Programming Reference Manual 15 32 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators To delete a cursor you must select it using the Start Selection and End Selection options on the Data Operations pop up menu and then cut the cursor with the Cut option on the same menu See the Selecting Array Cells section of Chapter 14 Array and Cluster Co
275. e in G Numeric values are written in hexadecimal unless otherwise noted The generic format of a type descriptor is lt length gt lt typecode gt Some type descriptors have additional information following the type code Arrays and clusters are structured or aggregate data types because National Instruments Corporation A 7 G Programming Reference Manual Appendix A Data Storage Formats Data Types they include other types For example the cluster type contains additional information about the type of each of its elements The first word 16 bits in any type descriptor is the length in bytes of that type descriptor including the length word You can reserve the high order byte of the type code for internal use When comparing two type descriptors for equality it is a good idea to ignore this byte two descriptors are equal even if the high order bytes of the type codes are not The type code encodes the actual type information such as single precision or extended precision floating point number as listed in the following table These type code values might change in future versions The xx in the type descriptor columns represent reserved values and should be ignored The following tables list scalar numeric and non numeric data types the type codes and type descriptors Table A 1 Scalar Numeric Data Types Data Type Type Code Type Descriptor numbers in numbers in hexadecimal hexade
276. e integers are limited to values from 128 through 127 although floating point numbers have the ranges shown in the following table Table 9 1 Range Options of Floating Point Numbers Precision Single Double Extended platform dependent Minimum 1 5E 45 5 0E 324 1 9E 4951 Positive Number Maximum 3 4E38 1 7E308 1 1E4932 Positive Number Minimum 1 5E 45 5 0E 324 1 9E 4951 Negative Number Maximum 3 4E38 1 7E308 1 1E4932 Negative Number i Note Although G can process in the range shown in Table 9 1 the range of extended floating point numbers it can represent and display in text format is 9 999D9DDI9IIDIDIDIDE 999 You can choose other limits within these natural bounds with the Data Range option from the pop up menu The following dialog box appears G Programming Reference Manual 9 6 National Instruments Corporation Chapter 9 Numeric Controls and Indicators Data Range Representation Manimum Increment 0 00E 0 Double Precision If Ualue is Out of Range Use Default Values Numeric Range Checking You also can limit intermediate values to certain increments For example you might limit word integers to increments of 10 or single precision floating point numbers to increments of 0 25 If you change either the limits or the increment you need to decide what to do if a VI or the operator attempts to set a value outside the range or
277. e path of the location of the path of the node is displayed If a function input does not need to be wired the default value is usually indicated in parentheses next to the name If the function can accept multiple data types the Help window shows the most common type The terminal names for subVI nodes are the labels of the corresponding front panel controls and indicators The default value of a subVI does not automatically appear in the wiring diagram It is a good idea however to include the default value in parentheses in the name of controls when you create a subVI When you place the Wiring tool over a wire the Help window displays the data type carried by that wire Also when you move the Wiring tool G Programming Reference Manual 1 8 National Instruments Corporation Chapter 1 Introduction to G Programming over different areas of the VI icon the corresponding connector terminal is highlighted in the Help window Attribute Node Help If you do not know the meaning of a particular attribute you can use the Help window to find out about the meaning of the attribute its data type and acceptable values If the attribute is a more complicated type such as a cluster then the Help window displays a hierarchical description of the data structure The following illustrations show an Attribute Node and the corresponding help information that is displayed as you move the cursor over different attribute names temp Is cont
278. e precision floating point numbers 000E 0040 0001 FFFF FFFF 0004 000A 0008 is the length of the entire type descriptor including the element type descriptor The array is variable sized so the dimension size is FFFFFFFF Notice that the element type descriptor 0004 000A appears exactly as it does for a scalar of the same type The following is an example of a type descriptor for a two dimensional array of Booleans 0012 0040 0002 FFFF FFFF FFFF FFFF 0004 0020 Cluster The type code for a cluster is 0x50 Immediately after the type code is a word containing the number of items in the cluster After this word is the type descriptor for each element in cluster order For example consider a cluster of two integers a signed word integer and an unsigned long integer 000E 0050 0002 0004 0002 0004 0007 000E is the length of the type descriptor including the element type descriptors National Instruments Corporation A 11 G Programming Reference Manual Appendix A Data Storage Formats The following is a type descriptor for a multiplot graph the numeric types can vary 0028 0040 0001 FFFF FFFF1D array of 001E 0050 0001 1 component cluster of 0018 0040 0001 FFFF FFFF 1D array of 000E 0050 0002 2 component cluster of 0004 000A double precision floating point number 0004 0003 long integer Flattened Data Two internal functions convert data from the format in memory to a form more suitable for writ
279. e procedure outlined in the Adding Subdiagrams section of this chapter If you wire a floating point number to the selector G rounds it to the nearest integer value G coerces negative numbers to zero and values higher than the highest numbered case to the last case i Note Case statements in other programming languages generally do not execute any case if a case value is out of range If you do not want out of range values to activate the highest or lowest cases you either must pretest the selector data for out of range numbers or include a trap case that does nothing for out of range values You can position the selector anywhere along the left border but you must wire the selector The selector automatically adjusts to the data type If you change the value wired to the selector from a numeric to a Boolean cases 0 and 1 change to FALSE and TRUE If other cases exist 2 through n G does not discard them in case the change in data types is accidental However you must delete these extra cases before the structure can execute G Programming Reference Manual 18 14 National Instruments Corporation Chapter 18 Structures The same principle applies if you wire an enumeration to the selector and there are more cases than items in the enumeration The diagram identifier for such cases is displayed as a grayed out numeric identifier to indicate that these cases must be deleted before the structure can execute The data at all input
280. e range If you wire 0 to the count terminal the loop does fi not execute iteration terminal National Instruments Corporation 18 3 G Programming Reference Manual Chapter 18 Structures While Loop c conditional terminal i iteration terminal The For Loop is equivalent to the following pseudocode for i 0 toN 1 Execute subdiagram A While Loop executes its subdiagram until a Boolean value you wire to the conditional terminalis FALSE G checks the conditional terminal value at the end of each iteration and if the value is TRUE another iteration occurs so the loop always executes at least once The default value of the conditional terminal is FALSE so if it is unwired the loop iterates only once The iteration terminal behaves exactly as it does in the For Loop The While Loop is equivalent to the following pseudocode Do Execute subdiagram which sets condition While condition is TRUE Both loop structures can have terminals called shift registers that you use for passing data from the current iteration to the next iteration See the Shift Registers section of this chapter for more information Placing Objects inside Structures You can place an object inside a structure by dragging it inside or by building the structure around the object You cannot put an object inside a structure by dragging the structure over the object If you move a structure and it overlaps another object
281. e the Browse button to specify the destination using a file dialog box in the usual way The Instrument Prefix text box shows the instrument prefix as shown by the function panel file This prefix is prepended by CVI to all C function names in the Function Panel tree The converter likewise prepends this prefix to the names of VIs it generates The suggested prefix is shown based on the DLL but you can change or delete this string as you want The remainder of the dialog box is devoted to the selection of function panels items to convert A list box lists all items in the function panel tree indented hierarchically by class as in LabWindows CVI The class names are listed as well but are grayed out and not selectable Initially all nodes found in the Function Panel file are selected Selected items are indicated by a checkmark symbol W non selected items by no symbol and class names by a rectangle National Instruments Corporation 23 9 G Programming Reference Manual Chapter 23 Calling Code from Other Languages Double clicking on an item toggles selection The Select All and Deselect All buttons can be used for convenience You also can click on an item once to move the highlighted bar to that item and click on Rename This pops up the following simple dialog box for renaming an FP item Rename FP Item Enter a new name for the Function Panel item This name will be used for the generated YI Initialize OK Can
282. e the X Scale Formatting or Y Scale Formatting pop up option to set the x axis or y axis scale format to Relative Time How do make the x axis of a chart display real time See the example VI called Real Time Chart vi located in general graphs charts 11b It unbundles the date time cluster from the Seconds to Date Time function into hours minutes and seconds It then converts these numbers into the number of seconds that have elapsed since midnight Finally this number is used as an input to the Xo and delta X attribute of a chart that has its x scale formatting set to Relative Time Or you can use the Absolute Time Format amp Precision option How do clear a chart programmatically Wire an empty array to the History Data attribute The data type of this empty array is the same as the data type wired to the chart There is an excellent example which illustrates this technique in general graphs charts 1llb How to Clear Charts amp Graphs vi How do avoid the flashing from the graph each time it is updated Use the Smooth Updates option to keep graphs from flashing This option is located in the Data Operations submenu of the graph pop up menu Using Smooth Updates means that panels first redraws the graphs to an off screen buffer before copying the image to the display While producing a smoother update to the indicators this option is generally slower and requires more memory Smooth Updates can be set globally thro
283. e under Windows 95 NT Slower machines might have lower resolution Macintosh Compact memory during execution Directs G to compact memory approximately once every 30 seconds Compaction reduces fragmentation by moving allocated memory to a single location A disadvantage to this option is that compaction takes time and might cause a short lull in performance while G is compacting memory G Programming Reference Manual 7 8 National Instruments Corporation Chapter 7 Customizing Your G Environment Macintosh Cooperation level With this option you can control how cooperative G is with other background applications If you set it to Low G does not share time very frequently with other applications Setting it low improves the performance of G but it causes the performance of any other applications that run in parallel to decrease If you set it to High G performance suffers but other applications have more time to execute Check available disk space during launch Checks amount of disk space available in the temporary directory as G launches You can check whether you want G to use the default in two cases abort if less than 500 KB or warn if less than 2 000 KB Note Changes to the Check available disk space during launch option take effect when you relaunch G Changes to the Use default timer Compact memory during execution and Cooperation level options take effect immediately Front Panel Preferences The Front Panel Pr
284. eased action changes the control value when you uJ l click on it and retains it until your VI reads it once or you release the kitt mouse button depending on which one occurs last For an example of Boolean controls and indicators see general controls booleans 1llb Customizing Booleans with Imported Pictures You can design your own Boolean style by importing pictures for the TRUE and FALSE state of any of the Boolean controls or indicators This process is explained in the Using the Control Editor section of Chapter 22 Custom Controls and Type Definitions G Programming Reference Manual 10 6 National Instruments Corporation String Controls and Indicators This chapter discusses how to use string controls and indicators and the table You can access these objects through the Controls String amp Table palette shown in the following illustration Using String Controls and Indicators A string control and string indicator are shown in illustration Indicator the following You enter or change text in the string control using the Operating tool or the Labeling tool As with the digital control new or changed text does not pass to the diagram until you press the lt Enter gt key on the numeric keypad click on the Enter button in the Tools palette or click outside the control to terminate the edit session Pressing the lt Enter gt Windows and HP UX or lt Return gt Macintosh and Sun key o
285. ecause the execution system can reclaim subVI data memory when the subVI is not executing Do not worry too much about copies of scalar values it takes a lot of scalars to make a dent in memory usage Do not overuse global and local variables when working with arrays or strings reading a global or local variable causes a copy of the data of the variable to be generated On open front panels do not display large arrays and strings unless it is necessary Indicators on open front panels retain a copy of the data that they display If the front panel of a subVI is not going to be displayed do not leave unused Attribute Nodes on the subVI Attribute Nodes cause the front panel of a subVI to remain in memory which can cause unnecessary memory usage Do not use suspend data range on time memory critical VIs The front panel for the subVI needs to be loaded to check range checking and extra copies of data are made for the subVIs controls and indicators In designing diagrams watch for places where the size of an input is different from the size of an output For example if you see places where you are increasing the size of an array or string frequently using the Build Array or Concatenate Strings functions you are generating copies of data Use consistent data types for arrays and watch for coercion dots when passing data to subVIs and functions when you change data types the output is a new buffer 26 18 National Instruments
286. ecause you use both frequently The String palette also contains both a string control and a string indicator The Find Terminal option on the control and indicator pop up menus highlights the block diagram terminal for the control or indicator This option is useful for identifying a particular object on a crowded block diagram The Create Attribute Node option creates an Attribute Node for the object You can use Attribute Nodes to control various properties of the object programmatically The Show submenu shows a list of the parts of a control that you can choose to hide or show such as the name label When editing a VI the pop up menu for a control contains a Data Operations submenu Using items from this menu you can cut copy or paste the contents of the control set the control to its default value make the current value of the control its new default and read or change the control s description When editing a VI you can paste data into an indicator Some of the more complex controls have additional options for example the array has options you can use to copy a range of values and to show the last element of the array The following illustration shows the edit mode Data Operations submenu for a numeric control This submenu is the only part of the pop up menu of a control available while the VI is running Reinitialize to Default Make Current Value Default Cut Data Copy Data Paste Data Description Online Help
287. eceseeeeseeeeeeseneeaee 3 11 Number of Connections 2 0 0 0 cece ceseeeecesceseeeeceseeeeeeseeeeecaeesaeceesaeenees 3 12 CY CIES EE E AE aeiinues Beet Meares kes 3 12 Attribute Nodes within Loops cee ceeeeeeeeeeseeeeeeeeeeenee 3 12 Tlogical Selections i is pis aana 3 13 Locals and Front Panel Terminals within Loops 3 13 Case Structures Containing Attribute Nodes Locals or Front Panel Terminals 0 00 cece eseeceeeeeeeeeeeeeeneeaee 3 13 Using the Hierarchy Window s sscsis sscecsossessceecves coves sctescossesvacoeseeasvenosnnscbeesssenscsvacesees 3 15 Opening the Hierarchy Window ee ceceseeeeceseeeeceeeeeeeeseeeeecaeesaecaeenaerae 3 15 Hierarchy Window Options ce ceceseeseeseceeceseeseceseeseceseeseeeneeseeeseesaecaeesaesaes 3 17 View Menu Options eee cece eseeesecssessecsecsseeeceseeseeeeeesevenseeeseneeaes 3 18 Hierarchy Toolbar Buttons eee ce ceeeeceneeeeceseeeeecaeesaeeseesaeenees 3 19 Hierarchy Node Pop Up Menu cece eeeeceseeeeseeeeeeeeseeseecneenaeeaes 3 20 Hierarchy Node Mouse Click Sequences 00 0 0 eee eeeeeeseeseeeeeneeeaee 3 21 Finding Hierarchy Node Mechanism ou ce ceceesececeseeeeceseeeeceeeeeeeeneeeeseneeaee 3 22 Finding VIs Objects and Text aisin eisers ssis eiere tes setesi asiat pepin sE e risi TESSE 3 23 Find Dialog Box rosene eene a ea E ctv EE EEA EEEE SEE 3 24 Finding VIs and Other Objects eee ceseeeeceseeeeceeeeseseeeeeeeeneeaes 3 24 Finding Tekt
288. ecting from the type definition removes the restrictions on the data type of the control and appearance making it into an ordinary control You cannot re establish that connection unless you find the type definition and replace the control with it Cluster Type Definitions If you use a type definition or strict type definition that is a cluster it is a good idea to use the Bundle By Name and Unbundle By Name functions on the block diagram to access the elements of the cluster instead of the Bundle and Unbundle functions These functions reference elements of the cluster by name instead of by cluster order and are not affected when you reorder the elements or add new elements to the cluster type definition If you delete an element that you are referencing in Bundle by Name or Unbundle By Name you have to change your block diagram Refer to the description of these functions in Chapter 14 Array and Cluster Controls and Indicators for more information G Programming Reference Manual 22 22 National Instruments Corporation Calling Code from Other Languages Chapter This chapter explains various methods of calling code written in other languages These methods include using platform specific protocols creating a Code Interface Node to call code written specifically to link to VIs and using a Call Library Function node to call Dynamic Link Libraries DLLs in Windows Code Fragments on the Macintosh and Shared Libraries on UNIX
289. ecting the global variable from the Functions Structures palette Global Yariabl GLOBE LOCAL global node A node for the global variable appears on the block diagram National Instruments Corporation 21 1 G Programming Reference Manual Chapter 21 Global and Local Variables Double click on the node to open a front panel You use this panel to define the data type for one or more global variables Note Assign a name to each control because you must refer to a specific global variable by name After you have defined the data types for the global variables save the global VI The following illustration is an example front panel describing three global types a number a string and a cluster containing two values Global 4 ee After you place a global variable on a block diagram and define a front panel for it the node is associated with the front panel Because a global variable can define multiple globals you must select which global you want to access from a particular node Select a global variable by popping up on the node and selecting the item by name from the Select Item menu as shown in the following illustration Or you can click on the node with the Operating tool and select the item you want G Programming Reference Manual 21 2 National Instruments Corporation Chapter 21 Global and Local Variables Change To Read Global Select item number Find string Online Help Description
290. ections of Diagrams 000 0 cece eeeceseeeeceseeeseeeeeeeeeeeeeeeens 4 31 Chapter 5 Printing Vis Printing in Gi so E E EE Dude wind des ae ued Hadise 5 1 Printing Configuration lt sesiscicesccegis cd eiser erari pe E E cape EEE Eat 5 1 PostScript Printing osios eoir Ses chs cosia on ieo e ei 5 2 Printing the Active Window sisisisessiriisssecstsiis nierstene iisen is sorpa seste eiei 5 2 Selecting Print Options 0 ee eee cseeeecseessecseceseeseceseeseceeeeseseeeeeseaseaeeeaeeaee 5 3 Setting Printout Formats sissies erresis skiresi 5 3 Choosing Layout Options 0 eee eeceeceeeeeeceseseeeeseeeeecaeesaessaeeaes 5 4 Creating Custom Print Settings eee ceeeeecseeesecneceseceeceseeeeeeeeees 5 4 Printing Section Headers ee eeeececeeeeeeeeeeseeeeseeeseenes 5 6 Programmatic Prnting ccccs y cssccvseescsveseestscheesveptanes ie Erre aov ees Er Ee aieas 5 7 Controlling When Printouts Occur oo ee eee ceceeeeeeeeeeeeeeeaeeeneeaee 5 7 Enhancing Printouts i s isei ss secsbes pegs scseedssceaseevasents stesso scadesseenscs sees 5 7 Setting Page Layout es aeee ne E o EEEE KE EEEa KEES 5 8 Using Alternative Printing Methods sseesssseseeseesrsreererreerrsseerssrerrsreresreseeres 5 9 G Programming Reference Manual viii National Instruments Corporation Table of Contents Chapter 6 Setting up Vis and SubVIs Creating Pop Up Panels iseci nineties neiere sen irene e E sue TE RE E e ates 6 1 VISetup Options i
291. ed option 6 4 pull down menus 2 6 Purge Data option 4 6 Q questions about G charts and graphs B 1 to B 4 error messages and crashes B 4 to B 5 miscellaneous questions B 9 to B 16 platform issues and compatibilities B 6 printing B 7 to B 9 R radix for integers selecting 9 4 Range Error indicator 4 14 range options for digital controls and indicators 9 6 to 9 7 Data Range dialog box 9 7 floating point numbers table 9 6 numeric range checking 9 7 to 9 9 Coerce option 9 7 correcting invalid values 9 8 to 9 9 Ignore option 9 7 Suspend option 9 8 range of extended floating point numbers note 9 6 Record marked for deletion button 4 6 rectangle tool Icon Editor 3 3 Redo Layout button 3 19 National Instruments Corporation Redraw option 3 18 reentrant execution enabling 24 5 examples storage VI not meant to share data 24 7 to 24 8 VIs that wait 24 5 to 24 7 purpose and use 24 5 refnum controls 12 2 to 12 5 Byte Stream File RefNum 12 5 Data Log File RefNum 12 3 to 12 5 Device RefNum 12 4 Network Connection RefNum 12 4 12 5 Occurrence RefNum 12 4 purpose and use 12 3 types 12 3 Reinitialize to Default option arrays 14 12 14 13 Probe tool 4 25 Reinitialize to Default Values option 14 21 Remove All command 18 12 Remove Bad Wires option 4 10 17 11 17 14 Remove Case option 18 20 Remove command 16 10 18 17 Remove Dimension option 14 7 Remove Element command 18 11 to 18 1
292. ee Chapter 13 List and Ring Controls and Indicators National Instruments Corporation 9 23 G Programming Reference Manual Chapter 9 Numeric Controls and Indicators Color Box The color box displays a color corresponding to a specified value The color value is expressed as a hexadecimal number with the form RRGGBB in which the first two numbers control the red color value the second two numbers control the green color value and the last two numbers control the blue color value An example is shown in the following illustration L You can set the color of the color box by clicking on it with either the Operating or Color tool to display a Color palette as shown in the following illustration Releasing your mouse button on the color you want selects that color EE E E ENHA ri OOOOOOOOOOOoOoOooooooo0o000 Color boxes typically are used on the front panel as indicators The easiest way to set the color of a color box is to use the color box constant from the Functions Numeric Additional Numeric Constants palette in the block diagram window Wire the color box constant to the color box terminal on the block diagram Clicking on the color box constant with either the Operating tool or the Color tool displays the same Color palette that you use to set the color box If you want to change the color box indicator on the front panel to various colors which indicate different conditions you can use a series of color box co
293. ee Code Interface Node To make a copy of a control or some other G object by clicking the mouse button on it while pressing the lt Ct r1 gt Windows lt option gt Macintosh lt meta gt Sun or lt Alt gt HP UX key and dragging the copy to its new location UNIX You also can clone an object by clicking on the object with the middle mouse button and then dragging the copy to its new location A set of ordered unindexed data elements of any data type including numeric Boolean string array or cluster The elements must be all controls or all indicators Front panel object that contains the elements of a cluster G 3 G Programming Reference Manual Glossary Code Interface Node CIN coercion coercion dot Color tool Color Copy tool compile conditional terminal connector connector pane constant continuous run control control flow Controls palette conversion count terminal G Programming Reference Manual Special block diagram node through which you can link conventional text based code to a VI The automatic conversion G performs to change the numeric representation of a data element Glyph on a node or terminal indicating that the numeric representation of the data element changes at that point Tool you use to set foreground and background colors Copies colors for pasting with the Color tool Process that converts high level code to machine executable code VIs are c
294. ee cee ceseeseceseeseceseeeeeeeeeeeseneeaeeeaeeaee 9 33 Polymorphic Units innana retoer rea a AE E E indie 9 35 G Programming Reference Manual X National Instruments Corporation Table of Contents Chapter 10 Boolean Controls and Indicators Creating and Operating Boolean Controls and Indicators 0 0 0 ee ee eeceeeeeeeeeeeeeeeeeee 10 1 Configuring Boolean Controls and Indicators 000 eee ese ceeceseeeeceseeeeceeeeeeseeeeeeseneeaee 10 3 Changing Boolean Labels ccc c cccsscescsseetssasivesivstescscvecssnsvceesecvasbusessteivensacts 10 3 Stopping on a Boolean Valle eee ceeeecse cee cneceseeseceseeseeeseeeeees 10 4 Boolean Data Range Checking 0 eee cesses ceseeeeceeeeseeeeeeeeeeeeenes 10 4 Configuring the Mechanical Action of Boolean Controls 10 4 Customizing Booleans with Imported Pictures elec eee ceeceseeeeeeeeeeeeees 10 6 Chapter 11 String Controls and Indicators Using String Controls and Indicators eee seesecseceseeseceseeeeceeeeeeseeeesesesesseecaeesaeeaes 11 1 String Control and Indicator Options eee ee eeeeseceeceeeseceseeeeceeceeeeeseeseseneesaecaecnaeraes 11 2 Scrollbar Opto ss sree ext evens Ris eed Saree sivccesnens a E E N A A R 11 3 Display Types 3 iene he Sead pein its ABER Ree AOR Bee 11 3 Normal Display Option e a ee cseeeceeceseeseceeeeceeeeseseeeeneseneaee 11 3 Backslash Codes Display Option eee eeeeeeeeseeseeeseeneeeaes 11 3 Password Display O
295. eeds to be reentrant z2 National Instruments Corporation 24 5 G Programming Reference Manual Chapter 24 Understanding the G Execution System Time To Wake Mel Time Seconds 27076998 Get Time Seconds In Seconds to Date The Get Time In Seconds function reads the current time in seconds and the Seconds to Date Time and converts this value to a cluster of time values year month day hour minute second and day of week A Bundle function replaces the current hour and minute with values representing a later time on the same day in the front panel Time To Wake Me cluster control The adjusted record then is converted back to seconds and the difference between the current time in seconds and the future time is multiplied by 1 000 to obtain milliseconds The result passes to a Wait function Lunch and Break are two VIs that use Snooze as a subVI The Lunch VI whose front panel and block diagram are shown in the following illustration waits until noon and pops up a front panel reminding the operator to go to lunch The Break VI pops up a panel reminding the operator to go on break at 10 00 a m The Break VI is identical to the Lunch VI except that the pop up subVIs are different G Programming Reference Manual 24 6 National Instruments Corporation Chapter 24 Understanding the G Execution System For Lunch and Break to execute in parallel Snooze must be reentrant Otherwise if you started Lunch first Break would h
296. eeeaeeaee 22 1 Applying Changes from a Custom Control ce eeeeeeeeseeeeceeeeeeeeeeeseeeeeeneees 22 3 Valid Custom Controls oc eeeeceeceeeecnseseecseceseesecesceseseeseeseaeeeneeaes 22 3 Savin Custom Controls sssi E E A S E E E 22 4 Using CustomCo trolS s spi e E E E RS 22 4 Making Icons e aree eenaa ne aa Se i Oe ATE AONE E nenie 22 5 Independent Instances of Custom Controls sseseesseeesesesessseereseeersreererrseeeesee 22 5 Customize Mode Optio D e E comers Ea E E R E R N E ENE 22 5 Independent Parts nioni EE A ei E E ERSS 22 6 Control Editor Parts WINdOW s s issssersssissiserseviiseeoikoroivseriheetsnsdrshesssiooseseseipose 22 7 Customize Mode Pop Up Menus for Different Parts ssseeeeneeereeerreresrerseees 22 9 Cosmetic Paitsi enre i e R E E E AE ET 22 9 Cosmetic Parts with More than One Picture s 22 11 Cosmetic Parts with Independent Pictures 00 0 eee eee eeteeeeeeeeees 22 12 Text Par S 8s teeta Se ei tn de Re a O 22 14 Scale Parts ve sc520 irks sees Shee E E ES A A uavbaen abbas suns eeeesneeeads 22 15 Controls as Parts 2 8s eee Rae tha Ae ae a 22 15 Adding Cosmetic Parts to Custom Controls 0 cee ceceseeseceseeeeceeeeeeeeeeeeeeees 22 17 Custom Control Caveat 0 0 eeeceeseesseseecsseseecsecsseesecssessecesceseeeeeeseeeeseaeeeesenes 22 18 Type DELMILNONS suie re a e e nina sv seoeeee E A E EEE E teen abet 22 19 General Type Definition Matching Data Types esssesseseesesseresssrrrrsreersrrsrrees 22 19
297. efault font It is used in the Controls palette the Functions palette and for new controls G Programming Reference Manual 27 2 National Instruments Corporation Chapter 27 Portability Issues Windows The U S version of Windows usually uses the Arial font The size depends on the settings of the video driver because you frequently can set up higher resolution video drivers to use Large Fonts or Small Fonts In the Japanese version of Windows the application uses the font that Windows uses for file names in the program manager Macintosh The application uses the same font used in the Finder for file names for the Application font For example on the U S Macintosh system the application uses Geneva although on the Japanese Macintosh system the application uses Osaka UNIX The application uses Helvetica by default e The System font is the font used for menus Windows The application uses Helvetica with the size dependent upon the video driver Macintosh The application normally uses Chicago in the U S system software Osaka in the Japanese system software and so on UNIX The application normally uses Helvetica for this font e The Dialog font is the font G uses for text in dialog boxes Windows In the U S version of Windows this font is a bold version of the Application font In the Japanese version of Windows this font is the same as the System font Macintosh The ap
298. eference Manual 15 10 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators The second data type is an array of plots where a plot is a cluster of an x array and a y array The following diagram illustrates how you can create this kind of data array of cluster of x and Es a a aa e Setting Custom Options on a Graph Both graphs have optional parts that can be shown or hidden using the Show submenu of the graph pop up menu These options include a legend from which you can define the color and style for a particular plot a palette that you use to change scaling and format options while the VI is running and a Cursor palette that you use to display multiple cursors Following is a picture of a graph showing all of these optional components except for the Cursor palette which is illustrated in the Graph Cursors section National Instruments Corporation 15 11 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators major grids minor grids legend Graphs have many options you can use to customize your data display The graph pop up menu is shown in the following illustration Transpose Array is available with the waveform graph only Change to Control Find Terminal Show gt Data Operations P Create gt kou Mispisiea tipi Replace H Scale Y Scale PTRAYEG iG et Hae age Scale Options Graphs automatically adjust their horizontal and vertical s
299. eferences dialog box is shown in the following illustration Front Panel Ei Use smooth updates during drawing C Open the control editor with double click C End text entry with Return key same as Enter key Override system default function key settings Use localized decimal point C Use transparent name labels Blink speed milliseconds 1000 Ml Use default The options in this dialog box are as follows Open the control editor with double click Makes easy access available to the Control Editor window where you can customize the appearance of a front panel control or indicator National Instruments Corporation 7 9 G Programming Reference Manual Chapter 7 Customizing Your G Environment End text entry with Return key same as Enter key Makes the lt Enter gt Windows lt return gt Macintosh lt Return gt Sun or lt Enter gt HP UX on the alphanumeric keyboard function like the lt Enter gt key on the numeric keypad ending text entry If you select this option you can embed new lines by pressing lt Ctrl Enter gt Windows lt option return gt Macintosh lt meta Return gt Sun or lt Alt Return gt HP UX Windows Macintosh Override system default function key settings By default your operating system might use some function keys for system purposes For example on the PC pressing F10 is the same as pressing the lt Break gt key On the Macintosh F1 to F4 usually are treated as
300. efinitions Only the background picture for the text part is shown in the Parts window not the text itself The background picture can be customized not the text Scale Parts A scale is a special kind of text part with markers for the text A picture of the scale is the background for each of its markers This background is usually a transparent rectangle and therefore not visible but you can see it if you color one of the scale markers A scale has the same options on its pop up menu as a text part along with other options relating only to scales This menu is shown in the following illustration Copy to Clipboard Import Picture Import at Same Size Revert Original Size Format amp Precision Style Mapping Reverse Ticks Reverse Ticks changes the tick marks on a vertical scale from the right side to the left or from left to right On a horizontal scale it changes the tick marks from the top to the bottom or from bottom to top On a rotary scale such as the scale on a knob dial gauge or meter it changes the tick marks from the outside to the inside or from the inside to the outside Reverse Ticks does not move the scale You can position the scale by dragging it when you are in customize mode Hold the lt Shift gt key down when dragging the scale of the slide to restrict the movement to one direction only Controls as Parts A control can include other controls as parts A common example of this is the digital
301. eive your comments on our products and manuals We are interested in the applications you develop with our products and we want to help if you have problems with them To make it easy for you to contact us this manual contains comment and configuration forms for you to complete These forms are in Appendix C Customer Communication at the end of this manual National Instruments Corporation XXV G Programming Reference Manual Chapter Introduction to G Programming This chapter discusses the unique G approach to programming It also explains how to start using G to develop programs What Is G G is the programming language that has been at the heart of LabVIEW for several years Currently it is integral to two of National Instruments application development environments LabVIEW and BridgeVIEW G like C or BASIC is a general purpose programming language with extensive libraries of functions for any programming task G includes libraries for data acquisition GPIB and serial instrument control data analysis data presentation and data storage G also includes conventional program debugging tools so you can set breakpoints animate the execution to see how data passes through the program and single step through the program to make debugging and program development easier G differs from those programming languages in one important respect Other programming systems use fext based languages to create lines of code
302. en A custom control always opens in the Control Editor window Changes you make to a custom control when you open it do not affect VIs that are using that control When you use a custom control on a front panel there is no connection between that instance of the custom control and the file or VI library where it is saved each instance is a separate independent copy You can however create a connection between control instances on various VI front panels and the master copy of the control To do this you must save the custom control as a type definition or a strict type definition Then any changes you make to the master copy affect all instances of the control in all the VIs that use it See the Type Definitions section later in this chapter for more information Customize Mode Option You can make more extensive changes to a control in the customize mode of the Control Editor Change between edit and customize mode by clicking on the mode button in the toolbar belonging to the Control Editor or by selecting Change to Customize Mode or Change to Edit National Instruments Corporation 22 5 G Programming Reference Manual Chapter 22 Custom Controls and Type Definitions Mode from the Operate menu while the Control Editor is the active window as shown in the following illustrations roject Windows Help Print at Completion Log at Completion Data Logging suspend when Called Make Current Values Default Reinitialize All To De
303. ent pictures 22 12 to 22 14 more than one picture 22 11 to 22 12 options 22 10 to 22 11 Copy to Clipboard 22 10 Import at Same Size 22 11 Import Picture 22 10 to 22 11 Original Size 22 11 Revert 22 11 pop up menu 22 10 count terminal 18 3 crashes questions about B 4 to B 5 Create Attribute Node option 8 3 20 1 20 4 Create Constant option 16 13 Create Control option 16 13 Create Indicator option 16 13 creating VIs See building VIs lt Ctrl gt key bringing subVI block diagram to front 4 21 changing Icon Editor tools to dropper 3 4 cloning Attribute Nodes 20 4 cloning objects 2 13 creating new scale marker 9 17 to 9 18 cutting copying and pasting icons note 3 4 moving between array elements 14 13 moving between cluster elements 14 21 Step Into button shortcut 4 20 Step Out button shortcut 4 20 Step Over button shortcut 4 20 lt Ctrl b gt removing bad wires 4 10 G Programming Reference Manual lt Ctrl click gt copying and transferring colors 2 26 executing Show VI Hierarchy action 3 21 resizing working space 2 24 untacking last tack point note 17 3 lt Ctrl Enter gt embedding newlines 7 10 lt Ctrl f gt bringing up Find dialog box 3 24 lt Ctrl h gt help key 1 7 lt Ctrl m gt switching from run mode to edit mode note 6 6 lt Ctrl Shift gt bringing up temporary Tools palette 2 4 lt Ctrl y gt calling History window 14 6 cursors See graph cursors custom controls
304. ents Corporation 18 11 G Programming Reference Manual Chapter 18 Structures terminals is to choose Remove Element from the shift register pop up menu Selecting Remove All deletes the shift register Hempyp Eierne Remove All The left topmost terminal holds the value from the previous iteration i 1 The terminal immediately under the uppermost terminal contains the value from iteration i 2 and so on with each successive terminal If you initialize one left terminal of a shift register you must initialize all of them The following pseudocode shows a three value running average routine equivalent to the G block diagram a b 0 for i 0 toN 1 avg x i a b 3 b a a x i G Programming Reference Manual 18 12 National Instruments Corporation Chapter 18 Structures For an example of how a shift register is set up see general structs 1lb Random Average vi Case and Sequence Structures Both Case and Sequence structures can have multiple subdiagrams configured like a deck of cards of which only one is visible at a time At the top of each structure border is the subdiagram display window which contains a diagram identifier in the center and decrement and increment buttons at each side The diagram identifier indicates which subdiagram is currently displayed If the diagram identifier is numeric it is followed by a diagram identifier range which shows the minimum and maximum values for whic
305. eplace Normal Display Codes Display Password Display Hex Display Limit to Single Line G Programming Reference Manual 11 2 National Instruments Corporation Scrollbar Option Display Types Chapter 11 String Controls and Indicators The Scrollbar option from the string pop up Show submenu is disabled unless you have increased the size of your string enough for a scrollbar to fit If you select this option a vertical scrollbar appears on the string control or indicator as shown in the following illustration so that you can display text not visible in the string control You can use this option to minimize the space taken up on the front panel by string controls that contain a large amount of text If the menu item is dimmed you must make the string taller to accommodate the scrollbar before choosing this option While you can make the scrollbar in a string control or indicator appear after enlarging the object up and down arrows and the scrollbar slide do not appear until text actually rolls over the size of the window available for text Options in the middle section of the string pop up menu let you select whether a string displays data as it normally does displays backslash codes in place of nonprintable characters displays in password mode using an in place of each character or displays hexadecimal characters Normal Display Option The Normal Display option displays all characters as type
306. er VI comparable to a subroutine Similar to scope chart except a line sweeps across the display to separate old data from new data A method of execution in which individual tasks are separate cases in a Case Structure that is embedded in a While Loop Sequences are specified as arrays of case numbers Object or region on a node through which data passes G 12 National Instruments Corporation Tip strip tool toolbar Tools palette top level VI two dimensional tunnel type descriptor U universal constant user defined constant UUT V VI VI library virtual instrument National Instruments Corporation Glossary Small yellow text banners that identify the terminal name and make it easier to identify function and node terminals for wiring Special cursor you can use to perform specific operations Bar containing command buttons that you can use to run and debug VIs Palette containing tools you can use to edit and debug front panel and block diagram objects VI at the top of the VI hierarchy This term distinguishes the VI from its subVIs Having two dimensions such an array having both rows and columns Data entry or exit terminal on a structure See data type descriptor Uneditable block diagram object that emits a particular ASCII character or standard numeric constant for example pi Block diagram object that emits a value you set Unit under test See virtual i
307. er also can assign mouse and key events to the user interface code before rerunning a VI 4 If there is nothing of equal or higher priority the VI continues to execute When a VI wait completes or the I O finishes the VI is put back on the queue in order of its priority Synchronous Nodes As mentioned previously a few nodes are synchronous meaning they do not multitask with other nodes Code Interface Nodes CINs and all computation functions execute synchronously Most analysis VIs contain CINs and therefore execute synchronously For example an FFT executes to completion without assigning other tasks to execute in parallel regardless of how long the FFT executes Almost all other nodes are asynchronous Structures I O functions timing functions and subVIs that you build all execute asynchronously Prioritizing Tasks of the Same Priority Level There are two methods for prioritizing parallel tasks One is to change a VI s priority using the priority setting of VI Setup The other is to make strategic use of Wait functions In most cases you probably should not change the priority of a VI from the default priority Using priorities to control execution order might not produce the results you expect If used incorrectly using priorities to control execution order can result in completely pushing aside the lower priority tasks Wait Functions for Prioritizing Tasks Instead of using the priority setting in VI Setup you
308. er objects in the Hierarchy window and your cursor becomes idle over a node G displays the name of the node below the icon of the node If you prefer you can use an option in the View menu to show the full path instead of the name You can double click on any icon in the Hierarchy window to open the associated VI If you show the Help window and move the cursor over an icon G displays the Help window information for that VI Hierarchy Window Options Several options let you control the display of the Hierarchy window others let you perform actions on nodes displayed in the window Options are available in the View menu in buttons near the top of the Hierarchy window in the pop up menu of a node and through mouse clicks You also can access the View menu by popping up on an empty space in the Hierarchy window National Instruments Corporation 3 17 G Programming Reference Manual Chapter 3 Building SubVis View Menu Options The View menu contains the following options related to the display of the Hierarchy window Many of the options are also available from buttons near the top of the window G Programming Reference Manual Redraw Show All Vis Vertical Hierarchy Horizontal Hierarchy Include Uls in vi lib lt Include Globals Include Type Defs Full UI Path in Label Redraw Redraws the window layout to minimize line crossings and maximize symmetry which is useful after successive operations on hierarchy no
309. es the Performance Profiler a feature that shows you data about execution time of your VIs The second section discusses factors that affect run time speed The third section discusses factors that affect memory usage Performance Profiling The VI Performance Profiler is a powerful tool for determining where your application is spending its time as well as how it is using memory This information is invaluable in finding the hot spots of your application so that you can make the best use of the VIs that take up the most time It has an interactive tabular display of time and memory usage for each VI in your system Each row of the table contains information for a specific VI The time spent by each VI is broken down into several categories as well as summarized in a few statistics The Profile window calculates the minimum maximum and average time spent per run of a VI You can use the interactive tabular display to view all or parts of this information sort it by different categories and look at the performance data of subVIs when called from a specific VI National Instruments Corporation 26 1 G Programming Reference Manual Chapter 26 Performance Issues Select Project Show Profile Window to access the Profile window The following illustration shows an example of the window already in use Profiling Display Options BJ Timing Statistics EJ Timing Details Vi Time Sub Vis Time Total Time Average Financi
310. es not prompt you to enter a comment when you save or close a VI if the only changes you made were changes to the history Window Options The options to the right of the VI Setup Documentation dialog box create access to online help files that you have created Put your cursor in the Help Tag box and type in a topic to display for this VI Then type in the path to the help file in the Help Path box or click the Browse button and find the file The filename and path of the file appears in the Help Path box After you have set these options clicking on the online help icon at the bottom of the Help dialog box accesses the help file you selected See Chapter 1 Introduction to G Programming for information on creating your own help files The window options apply to the VI when it is in run mode but not in edit mode You can use these options to control the ability of a user to interact with the program by restricting access to G features and by changing the way the window looks and behaves You can make your VI look and act like a dialog box in that the user cannot interact with other windows while this window is open You also can remove the scrollbars and the toolbar and set a window to be centered or sized automatically to fit the screen G Programming Reference Manual 6 4 National Instruments Corporation Chapter 6 Setting up Vis and SubVIs The window options are shown in the following illustration Ul Setup Window Option
311. espond to a dialog box or time spent in a Wait function on a block diagram or time spent to check for mouse clicks The basic information that is always visible in the first three columns of the performance data consists of the following items e VI Time Total time spent actually executing the code of this VI and displaying its data as well as time spent by the user interacting with its front panel controls if any This summary is broken down into sub categories in the Timing Details described below For Global VIs this time is the total amount of time spent copying data to or from all of its controls To see timing information on individual controls in a Global VI you can double click on the name of the Global VI e SubVIs Time Total time spent by all subVIs of this VI This is the sum of the VI time described above for all callees of this VI as well as their callees etc National Instruments Corporation 26 3 G Programming Reference Manual Chapter 26 Performance Issues Total Time Sum of the above two categories calculating the total amount of time Timing Information When the Timing Statistics checkbox is checked the following columns become visible in the tabular display Runs Number of times that this VI completed a run For Global VIs this time is the total number of times all of its controls were accessed Average A verage amount of time spent by this VI per run This is simply the VI time div
312. ete decoration parts when you are in the Control Editor National Instruments Corporation 22 17 G Programming Reference Manual Chapter 22 Custom Controls and Type Definitions The following illustration shows a custom graph that has some decoration parts including the Title of Graph label the Legend label and the box around the legend parts Title of Graph Legend Signal my Baseline ee When you use a custom control on other front panels you can change the size of any decoration parts that you added but you cannot move them Custom Control Caveats There are some things you need to be aware of when you make custom controls e Pictures created on one platform look slightly different when loaded on another platform this applies to pictures imported into a Pict Ring or used as background on any front panel as well For example a picture with an irregular shape or a transparent background might have a solid white background on another platform See the Picture Differences section in Chapter 27 Portability Issues e Control Editor can change only the appearance of a control it cannot change the behavior of a control This has two implications You cannot change the way a control displays its data You cannot change the way a control behaves when you edit it especially when you resize it For example when you make a ring control taller the increment and decrement arrows also increase in height If
313. ete it An additional index National Instruments Corporation 14 7 G Programming Reference Manual Chapter 14 Array and Cluster Controls and Indicators display appears for each dimension you add Two methods for resizing are shown in the following illustrations Change to Control Find Terminal Show Data Operations Create Key Navigation Replace Add Dimension Remove Dimension Add Element Gap The dimension of an array is a choice you make when you decide how many identifiers it takes to locate an item of data For example to locate a word in a book you might need to go to the sixth word on the twenty eighth line on page 192 You need three indices 6 28 and 192 to specify the word so one possible representation for this book is a three dimensional array of words To locate a book in a library you indicate the position on the shelf which shelf which bookcase which aisle and which floor so if you represented this as an array it uses five dimensions To locate a word in a library then requires eight indices Array Index Display If you think of a two dimensional array as rows of columns the top display is the row index and the bottom display is the column index The combined display at the right shows the value at the specified position as shown in the illustration that follows G Programming Reference Manual 14 8 National Instruments Corporation Chapter 14 Array and Cluster Controls and Indicators row
314. ex display element display A new array shell has one index display an empty element display and an optional label National Instruments Corporation 14 5 G Programming Reference Manual Chapter 14 Array and Cluster Controls and Indicators There are two ways to define an array type You can drag a valid control or indicator into the element display window or you can deposit the control or indicator directly by popping up in the element display area of the array and selecting a control Either way the control or indicator you insert fills the empty display For example if you want to define an array of Booleans you either can drag a Boolean into the element display area or you can pop up in the empty element area and select a Boolean control Both methods are shown in the following illustrations Controls Boolean G Programming Reference Manual 14 6 National Instruments Corporation Chapter 14 Array and Cluster Controls and Indicators The pop up menu of the index display is shown in the following illustration Change to Indicator Find Terminal Show Data Operations Create Key Navigation Replace Add Dimension eros Dinner shar Add Element Gap Array Dimensions A new array has one dimension and one index display You resize the index vertically or select the Add Dimension option from the index display pop up menu to add a dimension You shrink the index vertically or select Remove Dimension to del
315. fault Change to Customize Mode Ctrl M Independent Parts All G controls are built from smaller parts For example a slide control consists of a scale a housing a slider the increment and decrement arrows a digital display and a name label The parts of a slide are pictured in the following illustration G Programming Reference Manual 22 6 National Instruments Corporation Chapter 22 Custom Controls and Type Definitions increment arrow Y name label digital display scale slider housing amp unit label decrement arrow A Slide Control When you switch to customize mode in the Control Editor the parts of your control become independent You can make changes to each part without affecting any other part For example when you click and drag on the scale of the slide with the Positioning tool only the scale moves You can select parts and align or distribute them using the Alignment or Distribution rings from the toolbar or change their layering order by selecting Move Forward or Move Backward from the Edit menu Customize mode shows all parts of the control including any that were hidden in edit mode such as a name label or the radix on a digital control Because the parts of a control are detached from each other you cannot operate or change the value of the control while in customize mode Notice that the Operating tool is disabled The Wiring tool is always disabled in a Contr
316. feature described in the Using the Probe Tool section of this chapter to observe intermediate data values Also check the error output of functions and subVIs especially those performing T O e Observe the behavior of the VI or subVI with various input values For floating point numeric controls you can enter the values NaN and Inf in addition to normal values e Check to make certain that execution highlighting is turned off in subVIs if your VI runs more slowly than expected Also close subVI windows when you are not using them National Instruments Corporation 4 15 G Programming Reference Manual Chapter 4 Executing and Debugging VIs and SubVIs G Programming Reference Manual Check the representation of your controls and indicators to see if you are receiving overflow because you have converted a floating point number to an integer or an integer to a smaller integer Also refer to the Recognizing Undefined Data section of this chapter Check the data range and range error action of controls and indicators They might not be taking the error action you want Check for For Loops that inadvertently might execute zero iterations and produce empty arrays Also refer to the Execution Highlighting and Recognizing Undefined Data sections of this chapter Verify that you initialized shift registers properly unless you specifically intend them to save data from one execution of the loop to another Check the order of cluster ele
317. ferences dialog box take effect immediately Color Preferences The Color Preferences dialog box is shown in the following illustration Colors do Sa Front Panel Use default colors LC Block Diagram E Scrollbar GE Coercion Dots ME Menu Text SS Menu Background Windows CNIX only N Bink Foreground E Blink Background This dialog box lets you change the colors used by G for various items If you do not select the Use default colors checkbox you can click on any rectangle to change the color The options are the following Front Panel You can select a color for the front panel of new VIs Changing the color does not affect old VIs Block Diagram You can select a color for the block diagram of new VIs Changing the color does not affect old VIs Scrollbar You can select a color for scrollbars This option affects only the VIs that are currently open Coercion Dots Y ou can select a color for the dots indicating coercion of numerical data This option affects only the VIs that are currently open Windows UNIX Menu Text You can select a color for text used in menus National Instruments Corporation 7 13 G Programming Reference Manual Chapter 7 i Note Customizing Your G Environment Windows UNIX Menu Background Lets you select a color for the background used in menus Blink Foreground Lets you select the foreground color for a blinking object Affects only a blinking object
318. g pseudocode pull down menus R reentrant execution representation resizing handles ring control scalar scale scope chart Scroll tool sequence local National Instruments Corporation Glossary Tool used to create probes on wires Automatic printing of a VI front panel after execution Simplified language independent representation of programming code Menus accessed from a menu bar Pull down menu options are usually general in nature Mode in which calls to multiple instances of a subVI can execute in parallel with distinct and separate data storage Subtype of the numeric data type of which there are signed and unsigned byte word and long integers as well as single precision double precision and extended precision floating point numbers both real and complex Angled handles on the corner of objects that indicate resizing points Special numeric control that associates 32 bit integers starting at 0 and increasing sequentially with a series of text labels or graphics Number capable of being represented by a point on a scale A single value as opposed to an array Scalar Booleans and clusters are explicitly singular instances of their respective data types Part of mechanical action chart and graph controls and indicators that contains a series of marks or points at known intervals to denote units of measure Numeric indicator modeled on the operation of an oscilloscope Tool used
319. g auto indexing If you use this technique you need to be careful that the array in which you are replacing values is large enough to hold the resulting data because Replace Array Element does not resize arrays for you An example of this process is shown in the following illustration Conditionally replace a value using Use Initialize Array Repl to create an array of Use Array Subset 1000 elements to set array to correct size G Programming Reference Manual 26 26 National Instruments Corporation Chapter 26 Performance Issues Example 2 Searching through Strings You can use the Match Pattern function to search a string for a pattern Depending on how you use it you might slow down performance by unnecessarily creating string data buffers The following illustration shows the Help window for Match Pattern regular expression m before substring string e EJ match substring offset 0 nan after substring offset past match Match Pattern Searches for a pattern Returns 1 if not found Assuming you want to match an integer in a string you can use 0 9 as the regular expression input to this function To create an array of all integers in a string you need to use a loop and call Match Pattern repeatedly until the offset value returned is 1 The following diagram is one method for scanning for all occurrences of integers in a string It initially creates an empty array and then each time through the loop
320. g File Open Revert is disabled e Original Size Sets the picture of a part to its original size This is useful for pictures that you imported from other applications and then resized Some of these pictures do not look as good as the original when resized and you might want to restore their original size to fix them If you have not imported a picture Original Size is disabled Cosmetic Parts with More than One Picture Some cosmetic parts have more than one picture which they display at different times These different pictures are all the same size and use the same colors For example the increment arrow of the slide is a picture of a triangle normally raised slightly from the background It also has another picture a recessed triangle that appears while you are clicking on it with the Operating tool to increment the value of the slide The National Instruments Corporation 22 11 G Programming Reference Manual Chapter 22 Custom Controls and Type Definitions illustration that follows shows the two pictures of an increment arrow in action A cosmetic part with more than one picture has the Picture Item option on its pop up menu as shown in the following illustration Copy to Clipboard ifieer f Pin dap a ppggri gf Seme Siva Revert dirien Sire Picture Item Picture Item displays all the pictures belonging to a cosmetic part The picture item that is currently displayed has a dark border around it When you imp
321. g Waveform and XY Graphs 000 0 ee eceeeeecseeesecseesseceecseesecseesecnseeeseeeeeeseneeaee 15 2 Plotting Single Plot Graphs 0 eee eee eseesee cee ceee cee ceaeeaeceeeseceseeeeeeeeaeeeeeeaa 15 2 Waveform Graph Data Types 00 eee ee ceseeesceeceeeeeeeeeeeeneeseecaeenaeraes 15 2 XY Graph Data Types cc ici ek tbieeneetibteees nendes donaseecseehetoetcots 15 3 Plotting Multiplot Graphs 00 eee eee ceee cee cneessececseeeeceseeeceeeeseseneseeseneeags 15 5 Waveform Graph Data Types 00 eee ceseeeceeceeeeeeeeeeeeneeseecaeenaeraes 15 5 XY Graph Data Types siscciscc scisesedcesscuesonsechsse ioetesbeeschescpugessdes seeds osaes es 15 9 Setting Custom Options on a Graph cece ceseeeeceeceeeeeeeeseseseeseesaeenaenes 15 11 Scale Opttons s scee sis ss csessscs cases acs ce sehen EEEE E EE E eevee es 15 12 Marker Spacing eon enoe eenei aeee a 15 13 Form ttin g ess ereire sereia TE a Ea a Eii 15 15 A toscales Aer chk ae E EE eE EE EE e E 15 17 Loose Fits eiiean nare erer E E E E E 15 17 Panning and Zooming Options s e ssssseesseeesesssesssrrrrsreersreererreseressenees 15 17 Legend Options einioes scents neh sscte sb vacsates shes sss enasesasepshssgoescedvss DESETE ERE 15 19 Waveform Charts visi ois ree n ting oes bison bianca ie Gh nein 15 22 Waveform Chart Data Types cece ceceeseceeceseeesceseeeeceeeeeseneeseecsessaecaeenaesaes 15 22 Waveform Chart Options oo eee eeeesecsseeseceeceseeseceseeeeceeeeeseseeseeeaeesaecaeesae
322. g box which changes the selected objects to the selected font and set of attributes When working with objects like slides which have multiple pieces of text remember that text selections affect the objects or text currently selected For example if you select the entire slide while selecting Bold the scale digital display and label all change to a bold font If you select only the label while selecting Bold only the label changes to bold If you select text from a scale marker while selecting Bold all the National Instruments Corporation 2 21 G Programming Reference Manual Chapter 2 Building Vis markers change to bold These three types of changes are shown in the following illustration Style PHS tify Bold Italic Underline AGaramond Outline AGaramond Bold Strikeout G Programming Reference Manual 2 22 National Instruments Corporation Chapter 2 Building VIs Resizing Objects You can change the size of most objects When you move the Positioning tool over a resizable object resizing handles appear at the corners of the object as shown in the following illustration When you pass the tool over a resizing handle the Positioning tool changes to the Resizing cursor Click on and drag this cursor until the dashed border outlines the size you want as shown in the following Resizing cursor illustration command string command string ATT TRI F440 PlaTT TRI FRA 40 To cancel a resizing opera
323. ges connecting its immediate callers and subVIs Show Immediate Sub VIs TIf the node is hiding all or some subVIs this option expands the node to show all of its immediate subVIs The edges connecting the node to its subVIs are highlighted in red The option is toggled with Hide All SubVIs Hide All SubVIs TIf a node is showing all immediate subVIs this option collapses the node to hide its entire subVI chain The option is toggled with Show Immediate SubVIs Show VI Hierarchy Makes the selected node the focus node and displays the nodes belonging to its call chain and subVI chain Unrelated roots are also visible but all of their sub VIs are hidden The edges connecting the call chain of a node and subVI chain are highlighted in red 3 20 National Instruments Corporation Chapter 3 Building SubVis Show All SubVIs Makes the selected node the focus node and expands its entire subVI chain The edges connecting the subVI chain of the node are highlighted in red Show All Callers Makes the selected node the focus node and expands its entire call chain The edges connecting the call chain are highlighted in red Edit Icon Displays the Icon Editor for editing of the icon of the node VI Setup Displays the VI Setup dialog box for the node Get Info Displays the Get Info dialog box for the node Open Front Panel Opens the front panel of the VI global or type definition Print Documentation Brings
324. h calling conventions you should use In Windows 3 1 almost all DLLs use Pascal calling conventions In Windows 95 NT almost all DLLs use standard C calling conventions Parameter Lists Initially the Call Library Function has no parameters and has a return value of void You can click on the Add a Parameter Before and Add a Parameter After buttons to add parameters to the function You can click on the Delete this Parameter button to remove a parameter You can use the parameter ring to select different parameters or the return value When selected you can change the parameter name to something more descriptive The parameter name does not affect the call but it is propagated to output wires Descriptive names make it easier to switch between parameters Indicate the type of each parameter using the type ring The return type is limited to either Void meaning the function does not return a value or Numeric shown in the following illustration Void Mumeric For parameters you can select Numeric String or Array data types as shown in the following illustration Numeric Array String When you select an option from the type ring you see more options you can use to indicate details about the data type and how to pass the data to the library function The Call Library Node has a number of different options for data types because of the variety of data types required by different libraries Refer to the documentati
325. h the structure contains a subdiagram nam Case Structure Case Structures Oooo Single frame Multiframe Sequence Structure Sequence Structure Sequence Siructures National Instruments Corporation 18 13 G Programming Reference Manual Chapter 18 Structures Case Structures fi selector Clicking on the decrement left or increment right button displays the previous or next subdiagram respectively Decrementing from the first subdiagram displays the last and incrementing from the last subdiagram displays the first subdiagram Other uses of the display window are explained in the Case Structures and Sequence Structures sections of this chapter See general structs 1lb SquareRoot vi for anexample of a Case Structure The Case Structure has one or more subdiagrams or cases exactly one of which executes when the structure executes This depends on the value of the Boolean or numeric scalar you wire to the external side of the selection terminal or selector If a Boolean is wired to the selector the structure must have two cases True and False If a numeric is wired to the selector the structure can have from 0 to 2 5_1 cases If you wire an enumeration to the selector there must be one subdiagram for each enumeration item The case identifiers are the same as the enumeration item names If the structure does not have the appropriate number of cases the VI in which it appears is broken To add more cases follow th
326. hange the size of the history and comment boxes by resizing the window Revision Numbers The revision number is also a part of the history of the VI and is an easy way to see if the VI has changed and how it changed if you commented on your changes The revision number starts at zero and is incremented every time you save the VI The current revision number the one on disk is displayed in the Get Info dialog box It is also displayed in the titlebar of the VI if the option to do so is checked in the dialog box of Edit Preferences History National Instruments Corporation 25 7 G Programming Reference Manual Chapter 25 Note Managing Your Applications The number displayed in the History window or VI window is the next revision number that is the number that is saved on disk if you save the VI It is the current revision number plus one When you add a comment to the history the next revision number is included in the header of the comment For example if you were to click on the Add button in the example your comment would be added to the history with the revision number 4 Then if you save the VI the current revision number would be 4 and the comment that applies to the changes you just made would be labeled with the same number The revision number is not incremented when you save the VI if the only changes you made were changes to the VI History In many cases there are gaps in revision numbers between comments
327. hanges you add the comment to the history by clicking on the Add button If there is a comment in the Comment box when you save the VI it is added to the history automatically Once you add a comment it is a permanent part of the history You cannot rewrite the history so be sure to check your comments before adding them G Programming Reference Manual 25 6 National Instruments Corporation Chapter 25 Managing Your Applications The box at the bottom of the window displays the history of the VI The dialog box shows a header for each comment in the history that includes the revision number of the VI the date and time and the name of the person who made the change You can see that three comments have been added to this history and each is displayed with a header Because the preceding illustration is only an example the comments are short you can make them as long as you want when editing your own VIs The History window is fairly large with the history showing but you can hide the history by clicking on the History arrow the small black triangle to the left of the word This makes the window small enough that it stays out of your way while you are editing the VI When you want to see the history again click on the same arrow and the history reappears An example is shown in the following illustration Widget Calculator vi History User Mame johann Hext Revision 4 Comment Added code for the new widgets You can also c
328. hat G only prompts you when you close a VI rather than every time you save You are prompted if the VI changed any time since you loaded it even if you have already saved the changes Note G does not prompt you to enter a comment when you save or close a VI if the only changes you made were changes to the history Record comments generated by the editor Causes the editor to insert comments into the History window when certain events occur The events that cause automatic comments are conversion to a new version of LabVIEW or Bridge VIEW subVI changes and changes to the name or path of the VI Show revision number in titlebar Adds the revision number to the header of the History window The revision number starts at zero and is incremented every time you save the VI It will not be incremented however if the only changes you made were changes to the VI history The login options are as follows Windows and Macintosh only Login automatically with the registration name Uses the name of the registered user of the application Show the login prompt at startup time Prompts you for a user name when your application is started The user name can be changed any time by selecting Edit User Name the prompt displays a menu of all user names so far entered into LabVIEW with this option National Instruments Corporation 7 19 G Programming Reference Manual Chapter 7 Customizing Your G Environment cP Note This option is a LabVIEW
329. he Documentation menu the Use History Defaults In Preferences Dialog option must be deselected If you select the option G uses the history preferences instead The history preferences are identical except that they set up the defaults used when you create any new VI although the VI Setup documentation options apply only to the current VI National Instruments Corporation 6 3 G Programming Reference Manual Chapter 6 Setting up Vis and SubVIs If you check the Add an entry every time this VI is saved option G adds an entry to the VI history every time you save the VI If you have not entered a comment in the Comment box of the History window only a header is added to the history The header contains the revision number if that option is checked in the Preferences History dialog box the date and time and the name of the VI If you check the Prompt for comment when this VI is closed option the History window appears so that you can enter a comment when you close a VI that has changed since you loaded it even if you already have saved the changes If you check the Prompt for comment when this VI is saved option the History window appears when you save so that you can enter a comment This is useful if you prefer to comment on your changes when you finish making them instead of as you are editing If you do not set this option you cannot change the history of the VI after you select Save until the save is finished i Note G do
330. he Operate Log at Completion option Selecting Operate Log at Completion enables automatic data logging for a VI if it is disabled and disables it if it is enabled To interactively log front panel data for a VI select Operate Data Logging Log ip Note A waveform chart returns only one data point at a time with front panel data logging If you wire an array into the chart indicator the data log contains the array subset that was displayed on the chart for that record Enter button Delete button Record marked for deletion button You can change the log file binding of a VI with the Operate Data Logging Change Log File Binding option You can select a specific record by typing the record number and then clicking on the Enter button or pressing the lt Enter gt key on the numeric keypad You can mark the selected record for deletion by clicking on the Delete button When the selected record is marked for deletion the Delete button changes to a full trash can Clicking on the full trash can unmarks the selected record for deletion Selected records are not deleted until you select Operate Data Logging Purge Data or until you switch out of data retrieval mode either by clicking on the OK button or selecting Retrieve again If any records still are marked for deletion when you switch out of data retrieval mode you are asked if you want to delete the marked records Click on the OK button to return to the VI who
331. he exact colors and number of colors that your video card has You are also limited by the number of colors that G allocates for your display National Instruments Corporation 15 41 G Programming Reference Manual Introduction to the Block Diagram Chapter This chapter describes terminals and nodes two of the three elements you use to build a block diagram the third consists of wires Terminals and Nodes Terminals You create block diagrams with terminals nodes and wires Terminals are ports through which data passes between the block diagram and front panel as well as between nodes on the block diagram Terminals underlie the icons of functions and VIs The following illustration shows an example of a terminal pattern on the left and its corresponding icon on the right To display the terminals for a function or VI pop up on the icon and select Show Terminals Nodes are program execution elements They are analogous to statements operators functions and subroutines in conventional programming languages Wires are the data paths between input and output terminals G has many types of terminals In general a terminal is any point to which you can attach a wire G has control and indicator terminals node terminals constants and specialized terminals on structures Terminals that supply data such as front panel control terminals node output terminals and constants also are called source terminals Node i
332. he following examples show only the Case Structure and its pop up menus For Sequence Structures replace the word case with the word frame A new Case Structure has two cases but can be edited to have one case as well A new Sequence Structure has one frame Moving between Subdiagrams The fastest way to view the next lower or higher subdiagram is to click on the decrement or increment button in the display window If you want to jump over several subdiagrams click on the subdiagram identifier and select the destination subdiagram from the pop up menu as shown in the following illustration You also can use the Show Case command from the border pop up menu G Programming Reference Manual 18 18 National Instruments Corporation Chapter 18 Structures Show Description Replace Remove Case Structure Show Case True Add Case After Add Case Before Duplicate Case Make This Case True Remove Case Adding Subdiagrams You can add subdiagrams several ways If you select the Add Case After command from the structure border pop up menu as shown in the illustration that follows G inserts an empty subdiagram after the currently visible one For example an empty subdiagram at position 3 is created from subdiagram 2 using Add Case After A complementary command Add Case Before appears in the same pop up menu These commands also appear in the diagram identifier pop up menu Show Description Replace gt Remove Cas
333. he following illustration shows how to resize a one dimensional array either vertically or horizontally to show more elements simultaneously The index display contains the index of the element in the left or upper left corner of the table By changing the index you can display different sections of a large or multidimensional array For one dimensional 1D arrays the index identifies the column of the left most visible element For two dimensional 2D or higher arrays the bottom two indices identify the coordinates of the upper left visible element In the left portion of the following illustration this element is 3 4 G Programming Reference Manual 14 10 National Instruments Corporation Chapter 14 Array and Cluster Controls and Indicators If you view a three dimensional 3D array as a book of pages that are composed of lines rows of characters columns the table displays part or all of one page The figure at the right in the following illustration shows the first four columns of the first two rows of page three of the array element 8 4 element 0 0 of page 3 pag Ta row T column If you want to hide the array indices pop up on the outer frame and turn off the Show Index Display option from the array pop up menu The following illustration shows an example of what a tabular array looks like without the index display If you want to display an array in an orientation different from the tabular array fo
334. he left to select the outline of a circle triangle or a more complicated shape like a musical note Other platforms might have to draw these irregular shapes on a rectangular white background In Windows 95 NT look for applications that support enhanced metafiles if you want pictures with irregular shapes and pictures that scale well e 9 National Instruments Corporation 27 5 G Programming Reference Manual Data Storage Formats Appendix This appendix discusses the formats in which you can save data This information is most useful to advanced users such as those using code interface nodes CINs and those reading from or writing to files used by the file I O functions This appendix explains how data is stored in memory the relationship of type descriptors to data storage and the method by which data is flattened for file storage on disk Data Formats for Front Panel Controls and Indicators Booleans Numerics Booleans are 16 bit integers The most significant bit contains the Boolean value If bit 15 is set to 1 the value of the control is TRUE if it is set to 0 the value is FALSE 15 o a Extended When extended precision numbers are saved to disk they are stored in a platform independent 16 bit format In memory the size and precision varies depending on the platform Windows Extended precision floating point numbers have 80 bit format 80287 extended precision format Ta 64 0 fs 15 exp O 6
335. he same locations in which you previously closed them G Programming Reference Manual 2 2 National Instruments Corporation Chapter 2 Building Vis If you pop up in an empty space in a front panel or block diagram window a temporary copy of the Controls and Functions palettes appear If you are using a small monitor you can close the floating Controls and Functions palettes and create objects with these pop up palettes instead You can position the front panel and block diagram side by side or above and below one another by selecting the Tile options from the Windows menu When you create front panel objects they appear with a blank label ready for you to enter the name of the new object If you want to give the object a name type in the name When you are finished entering the name end text entry by pressing the lt Enter gt key on the numeric keypad If you do not have a keypad you can press the lt Enter gt Windows and HP UX or lt Return gt Macintosh and Sun key click on the Enter button in the toolbar or click anywhere outside the label Note If you do not enter text into the label of a control when you first create it the label disappears when you click elsewhere You can show the label again by popping up on the control and selecting Show Label The following illustration shows an example of the result of popping up on the control and selecting Show Label Voltage Input 40 6 0 When you create an
336. he source cluster After you select a name you can wire a new value to National Instruments Corporation 14 25 G Programming Reference Manual Chapter 14 Array and Cluster Controls and Indicators that terminal to assign a new value to that element of the cluster An example of this is shown in the following illustrations You can resize the Bundle By Name function to show as many or as few elements as you need This is different from the Bundle function which requires you to size it to have the same number of elements as are in the resulting cluster G Programming Reference Manual 14 26 National Instruments Corporation Chapter 14 Array and Cluster Controls and Indicators If you pop up on the Bundle By Name function when the cluster contains a cluster you find a pull to the side submenu that you can use to access individual elements of the subcluster by name or select all elements The Bundle By Name function is useful when you are working with data structures that might change during the development process If your modification involves the addition of a new element or a reordering of the cluster the change does not require changes to the Bundle By Name function because the names are still valid For example if you modified the previous example by adding the new element and weight to the source and destination clusters the VI is still correct This example is shown in the following illustration Bundle By Name is
337. he terminals G Programming Reference Manual 17 12 National Instruments Corporation Chapter 17 Wiring the Block Diagram Multiple Wire Sources You can wire a single data source to multiple destinations but you cannot wire multiple data sources to a single destination In the example that follows you must disconnect one source During front panel construction you might have dropped a control when you meant to drop an indicator If you try to wire an output value to the terminal of a front panel control you see a multiple sources error Pop up on the terminal and select the Change To Indicator command to correct this error No Wire Source Two examples of wires with no sources are shown in the following illustration In one case a tunnel supplies data to the Reciprocal function but nothing supplies data to the tunnel In the other case two function inputs are wired together but there is no data source for them The solution to the problems is to wire a data source to the tunnel and to the Add and Increment functions respectively You also see this error if you wire together two front panel indicator terminals when one should be a control In this case pop up on one terminal and select the Change To Control command National Instruments Corporation 17 13 G Programming Reference Manual Chapter 17 Wiring the Block Diagram Loose Ends Loose ends shown in the illustration that follows are wire branches that do
338. hese ranges might be up to a few days wider depending on your time zone and if daylight saving time is in effect National Instruments Corporation 9 11 G Programming Reference Manual Chapter 9 Numeric Controls and Indicators Slide Numeric Controls and Indicators The slide controls and indicators are shown in the following illustration a Vertical Slide Mertical Pointer Slide 5 00 8 00 6 00 6 00 4 00 4 00 2 00 2 00 A 10 00 aE el T 7 0 00 0 00 Simple Horizontal Slide Horizontal Slide Horizontal Fointer Slide Each slide has a digital display You can use the digital displays to enter data into slide controls as explained in the Digital Controls and Indicators section of this chapter You can use the Operating tool on such parts as the slider the slide housing the scale and increment buttons to enter data or change values The slider is the part that moves to show the value of the control The housing is the stationary part that the slider moves on or over The scale indicates the value of the slider and the increment buttons are small triangles at either end of the housing An example of a slider is shown in the following illustration G Programming Reference Manual 9 12 National Instruments Corporation Chapter 9 Numeric Controls and Indicators You can drag the slider with the Operating tool to a new position If the VI is running
339. hift registers to ensure consistent behavior LabVIEW users should see Chapter 3 Loops and Charts of the LabVIEW Tutorial Manual for further information on using G Programming Reference Manual 18 10 National Instruments Corporation Chapter 18 Structures uninitialized shift registers Bridge VIEW users can refer to Chapter 10 Loops and Charts of the BridgeVIEW User Manual When the loop finishes executing the last value stored in the shift register remains at the right terminal If the right terminal is wired outside of the loop this last value passes out when the loop completes This property is shown in the following illustration Untitled 6 Diagram File Edit Operate File Edit Operate Project Windows Help Ea EREI JSE en o A Le initial value initial value number of iterations number of iterations output 132 To add or remove terminals to a particular shift register use the lL Resizing cursor to resize the left terminals Alternatively you can use Resizing cursor the Add Element command from the shift register pop up menu to add more left terminals to the shift register Added terminals appear directly below the one on which you pop up Use the Remove Element command to remove the terminal on which you pop up The following illustration shows both methods The only way to remove extra wired National Instrum
340. his figure applies only to the amount of memory the VI is using and does not reflect the memory used by any of its subVIs The memory usage is divided into space required for the front panel and the block diagram VI code and data space The memory usage can vary widely especially as you edit and execute the VI The block diagram usually requires the most memory When you are not editing the diagram save the VI and close the block diagram to free space for more VIs Saving and closing subVI front panels also frees memory You can save VIs as individual files or you can group several VIs together and save them in a VI library National Instruments Corporation 2 27 G Programming Reference Manual Chapter 2 Building Vis Individual VI Files Five options in the File menu concern saving your VIs as individual files Select the Save option to save a new VI choose a name for the VI and indicate its destination in the disk hierarchy Also use this option to save changes to an existing VI in a location previously indicated If you want to save a VI with a new name you can use Save As Save a Copy As or Save with Options from the File menu When you select the Save As option G saves a copy of the VI in memory to disk with the name you direct After the save is finished the VI in memory points to the new version In addition all callers to the old VI that are in memory now refer to the new VI If you enter a new
341. hose parts of the Custom Probe palette that might match the data type of the wire are enabled If you choose a control that cannot have the same data type as the wire G signals this mismatch with a beep For example with arrays and clusters you cannot use the array and cluster shells from the Array amp Cluster palette because they are not completed data types You can add your own palettes to the end of the Custom Probe palette just as you can add them to the Controls palette See Chapter 7 Customizing Your G Environment for more information on how to do this Placing Breakpoint Tools Breakpoint tool You can place a breakpoint on a VI node or wire to set a pause to occur during execution Nodes include subVIs functions structures Code Interface Nodes CINs Formula Nodes and Attribute Nodes When a block diagram has a breakpoint execution pauses after all nodes on the Clear Breakpoint cursor G Programming Reference Manual 4 26 National Instruments Corporation Chapter 4 Executing and Debugging Vis and SubVIs diagram have executed When a wire has a breakpoint execution pauses after data has passed through the wire When you reach a breakpoint during execution you can single step through execution probe wires to see their data change values of front panel controls or continue running to the next breakpoint or until execution is completed depending on which one occurs first To set a breakpoint select the Brea
342. i Numeric controls and indicators are either digital slide rotary ring enumerated color box or color ramp controls o 0 National Instruments Corporation 9 1 G Programming Reference Manual Chapter 9 Numeric Controls and Indicators Digital Controls and Indicators A digital numeric control and indicator are shown in the following illustration digital control digital indicator Digital numerics are the simplest way to enter and display numeric data alhy Use the Operating tool and any of the following methods to increase or decrease the displayed value Operating tool e Click inside the digital display window and enter numbers from the keyboard e Click on the increment or decrement arrow of the digital control or indicator e Place the cursor to the right of the digit you want to change and press the up or down keyboard arrow The Enter button appears on the Tools palette to remind you that the ente new value replaces the old only when you press the lt Enter gt key on Enter button the numeric keypad click outside the display window or click on the Enter button While the VI is running any of these actions prevent G from interpreting intermediate values as input For example while changing a value in the digital display to 135 you do not want the VI to receive the values 1 and 13 before getting 135 This rule does not apply to values you change using the increment decrement arrows Numeric con
343. i Basic G Concepts nenepn inoen e Sain cee Re A eaten xxi Front Panel ODEO S r a a reap na Ee E Mei eE EEEO STEE EAER xxii Block Diagram Programming sseeesssereesseeerereeerreesreserresreresrenrerenrerrnenenneeens xxii Advanced G Topi CS rnanan i i naa e eE S A EE E E SRS xxiii Appendices Glossary and Index esssesseseeesseseeesseeersrestsreererrsserrrsreresrererrreere xxiii Conventions Used in This Manual cece eee eceeeeeeeseeeseceecaecaesaeceeeesecesenseseeeeeeeeneees XXiV Related Documentation sesinin a ee s ii eae eee eE EE Ti oeie XXV Customer ComMUN Caton nesoni enS e E E RA E E E ES XXV Basic G Concepts Chapters 1 through 7 Chapter 1 Introduction to G Programming What ISG ispuni onres RRE E REE E E EEEE E ERER 1 1 Components ofa VI isto Bee a See a Gh ee eis oe 1 1 BrOnt Panne nse 2 ah EEEN ETNE EE EEEE ETE EE ESTES 1 3 Block Diagram innin a E TAE eet 1 4 Icon and Connector issees mienne e te anaes A ni 1 6 alioa K E conceit ga E te hae EE E ABR Sie E ie RE a 1 7 Front Panel Hel piisces deicesecsetlocstessuaecs bases thant ed bnneste gestae eta 1 7 Block Diagram Help eee n erR E S 1 7 Atteibute Node Helps oissserronvarecioots o a e E 1 9 Online Reference 46 enn ais SAA AR Be A eR Ae 1 9 Creating Your Own Help Files sverre ccvaecsev ests tipeer aeae E IEE SES SEAE isisi 1 9 National Instruments Corporation v G Programming Reference Manual Table of Contents Chapter 2 Building Vis G EnvirOnment
344. icators I Allow Drag Snap to point Lock to plot lt Plot 0 The Allow Drag option determines if you can move the cursor with the mouse If Allow Drag is selected you can move or drag the cursor If Allow Drag is deselected you cannot move the cursor around on the plot If you have Allow Drag selected the options below the dotted line of the menu determine how you can move the cursor with the mouse Select Free if you want to place or move the cursor anywhere on the graph Select Snap to Point if you want the cursor to always attach itself to the nearest point on any plot Select Lock to Plot to attach the cursor to a specific point The first time you select Lock to Plot the cursor attaches itself to the first point on the plot After freeing the locked cursor and moving it to any new position selecting Lock to Plot moves the cursor to the last location of the locked cursor Below the second dotted line of this menu is a list of the plots you can lock to for example Plot 0 Plot 1 Plot 2 and so on A large number of options are available for creating controlling and reading cursors or markers programmatically using the Attribute Node for a graph See Chapter 20 Attribute Nodes for further information Intensity Charts The intensity chart is a way of displaying three dimensions of data on a two dimensional plot by placing blocks of color on a Cartesian plane The intensity chart accepts a two dimensional array of
345. icons called nodes and wires that carry data between the nodes is the source code for the VI The block diagram resides in the block diagram window of the VI Backus Naur Form A common representation for language grammars in computer science Front panel objects used to manipulate and display or input and output Boolean TRUE or FALSE data Several styles are available such as switches buttons and LEDs G 2 National Instruments Corporation breakpoint Breakpoint tool broken VI Bundle node byte stream file C case Case Structure cast chart CIN cloning cluster cluster shell National Instruments Corporation Glossary A pause in execution You set a breakpoint by clicking on a VI node or wire with the Breakpoint tool from the Tools palette Tool used to set a breakpoint on a VI node or wire VI that cannot be compiled or run signified by a broken arrow in the run button Function that creates clusters from various types of elements File that stores data as a sequence of ASCII characters or bytes One subdiagram of a Case Structure Conditional branching control structure which executes one and only one of its subdiagrams based on its input It is the combination of the IF THEN ELSE and CASE statements in control flow languages To change the type descriptor of a data element without altering the memory image of the data See scope chart strip chart and sweep chart S
346. ided by the number of runs Shortest Minimum amount of time the VI spent in a run Longest Maximum amount of time the VI spent in a run When the Timing Details checkbox is checked you can view a breakdown of several timing categories that sum up to the time spent by the VI For VIs that have a lot of user interface these categories can help you see what operations are taking the most time G Programming Reference Manual Diagram Time spent only executing the code that was generated for the diagram of this VI Display Time spent updating front panel controls of this VI with new values from the diagram Draw Time spent drawing the front panel of this VI Draw time includes the following The time it takes simply to draw a front panel when its window just has been opened or when it is being revealed after being obscured by another window The time that is conceptually Display time because it is caused by new values coming in from the diagram but occurs because the control is transparent and or overlapped These controls must invalidate their area of the screen when they receive new data from the diagram so everything in that area can redraw in the correct order Other controls can draw immediately on the front panel when they receive new data from the diagram More overhead is involved in invalidating and redrawing most but not all of which shows up in the Draw timings Tracking Time spent tracking the mo
347. iform mode 9 17 National Instruments Corporation Scale pop up menu 9 14 to 9 15 slide pop up menu options 9 14 slide scale 9 14 to 9 19 text scale 9 18 to 9 19 smooth updates during drawing setting 7 10 Smooth Updates option 15 12 Snap to Point option 15 35 source terminals 16 1 space character backslash V code table 11 4 spacing distributing objects 2 12 speeding up VI performance See performance issues Stack Plots option 15 28 to 15 29 stacked plots 15 28 Start Selection option 14 14 to 16 15 32 Step Into button 4 20 Step Out button 4 20 Step Over button 4 18 4 20 stepping through VIs See single stepping through VIs Stop button hiding 4 4 purpose and use 4 1 4 4 Stop command 4 4 stopping VIs 4 4 strict type checking of units 9 33 to 9 34 strict type definitions attribute nodes available note 22 20 definition 22 19 purpose and use 22 19 to 22 20 saving 22 20 String amp Table palette 11 1 string constants pop up menu 16 5 user defined 16 4 string controls and indicators 11 1 to 11 9 attribute examples Boolean controls 20 11 to 20 12 list controls 20 13 to 20 14 ring controls 20 12 to 20 13 entering or changing text 11 1 to 11 2 illustration 11 1 National Instruments Corporation l 51 Index pop up menu options 11 2 to 11 6 Backslash V Codes Display 11 3 to 11 5 Display Types 11 3 to 11 5 Hex Display 11 5 illustration 11 2 Limit to Single Line 11 6
348. illustrated does not work for expanding functions like the Array Bundle function for example Wire Stretching You can move wired objects individually or in groups by dragging the selected objects to the new location using the Positioning tool The National Instruments Corporation 17 5 G Programming Reference Manual Chapter 17 Wiring the Block Diagram wires connected to the selected objects stretch automatically The wire stretching capability is demonstrated in the following illustration If you duplicate the selected objects or move them from one diagram into another for example from the block diagram into a structure subdiagram the connecting wires remain behind unless you select them as well C7 Note Wire stretching occasionally creates wire stubs or loose ends discussed in the Wire Stubs and Loose Ends subsections of the Solving Wiring Problems section of this chapter You must remove the stubs or loose wires for the VI to execute The easiest way to do this is to select the Edit gt Remove Bad Wires command Selecting Moving and Deleting Wires A wire segment is a single horizontal or vertical piece of wire The point at which three or four wire segments join is ajunction A bend in a wire is where two segments join A wire branch contains all the wire segments from junction to junction terminal to junction or terminal to terminal if there are no junctions in between One mouse click with the Positioning tool o
349. imes referred to as points have a special wire pattern Common Cluster Wire Pattern Cluster of Numbers Wire Pattern You can connect terminals only if they have the same type For clusters this means that both clusters must have the same number of elements and corresponding elements determined by the cluster order must match in type G coerces numbers of different representations to the same type National Instruments Corporation 14 19 G Programming Reference Manual Chapter 14 Array and Cluster Controls and Indicators For information on functions that manipulate clusters see the Online Reference Function and VI Reference Cluster Functions topic Creating Clusters You create a cluster control or indicator by installing any combination of Booleans strings charts graph scalars arrays or even other clusters into a cluster shell You access the cluster shell from the Controls palette as shown in the following illustration Controls x Array amp Cluster A new cluster shell has a resizable border and an optional label When you pop up in the empty element area the Controls palette appears You can place any element from the Controls palette in a cluster You can drag existing objects into the cluster shell or deposit them directly inside by selecting them from the cluster pop up menu The cluster takes on the data direction control or indicator of the first element you place in the cluster as do subsequently ad
350. in used if mode Change 232 used if mode Get lower limit lower limit used if mode Change DBL used if mode Get upper limit lupper limit used if mode Change ps1 used if mode Get For 1 000 elements this implementation is twice as fast as the previous implementation and four times faster than the original implementation Case Study 3 A Static Global Table of Strings The previous example looked at an application in which the table contained mixed data types and the table might change frequently In many applications you have a table of information that is fairly static once created The table might be read from a spreadsheet file Once read into memory you mainly use it to look up information National Instruments Corporation 26 35 G Programming Reference Manual Chapter 26 Performance Issues In this case your implementation might consist of the following two functions Initialize Table From File and Get Record From Table spreadsheet file i number of records error Initialize Table From File wi record number record Get Record error Get Record From Table vi One way to implement the table would be to use a two dimensional array of strings Notice that the compiler stores each string in an array of strings in a separate block of memory If there are a large number of strings for example more than 5 000 strings you might put a load on the memory manager This l
351. in Object s Data amp Parts 3 27 fonts Search in Object s Label 3 27 Application font 2 18 Search in VIs 3 27 changing fonts 2 16 to 2 22 VIs and other objects 3 24 to 3 25 applying changes to selected objects Find Hierarchy Node mechanism example 2 21 to 2 22 3 22 to 3 23 example 2 19 to 2 20 Find Next command 3 29 Dialog font 2 18 Find pop up menu differences when porting VIs between Attribute Nodes 3 29 platforms 27 2 to 27 4 global and local variables 3 29 predefined fonts 2 18 27 2 to 27 3 Find Terminal option 8 3 20 6 System font 2 18 Find Wire option 4 24 to 4 25 For Loops flattened data auto indexing arrays A 13 to A 14 overview 18 7 to 18 8 clusters A 14 setting the count 18 8 handles A 13 avoiding cycles in subVIs 3 13 overview A 12 to A 13 avoiding unnecessary computations paths A 13 26 9 to 26 11 scalars A 13 executing zero times 18 9 strings A 13 icon for 18 2 18 3 Flip Horizontal command 3 6 placing objects inside structures Flip Vertical command 3 6 18 4 to 18 5 floating point operations and undefined data purpose and use 16 11 18 3 to 18 4 4 17 to 4 18 shift registers 18 10 to 18 13 floating point representation 9 4 terminals inside loops 18 6 to 18 7 Font dialog foreground and background colors 2 25 Diagram Default checkbox 2 18 foreground background tool Icon Editor 3 4 illustration 2 17 form feed backslash V code table 11 4 Panel Default checkbox 2 18 Format amp Precisi
352. in its blink state Blinking is a basic attribute turned on with Attribute Nodes See Chapter 20 Attribute Nodes for more information Blink Background Lets you select the background color for a blinking object Affects only a blinking object in its blink state Use default colors Uses the default choice of colors for all items listed in this dialog box You must turn this off if you wish to change any of these colors UNIX Provide extra colors Toggles between a 216 color palette and a 125 color palette A larger palette can cause a noticeable flash when you switch between windows Changes to options in the Color Preferences dialog box take effect immediately Font Preferences The Font Preferences dialog box lets you change three categories of predefined fonts the Application font System font and Dialog font You select the category of font you wish to change from the pop up menu above the text box The dialog box with Application Font selected is shown in the following illustration G Programming Reference Manual 7 14 National Instruments Corporation Chapter 7 Customizing Your G Environment Preferences Application Font The quick brown fox jumps over the lazy dog Use default font Custom fon G uses the three categories of fonts for specific portions of its interface The fonts are predefined according to the platform as follows Use default font Uses the default font as defined by G in
353. in the Controls Graph palette A graph indicator is a two dimensional display of one or more plots The graph receives and plots data as a block A chart also displays plots but it receives the data and updates the display point by point or array by array retaining a certain number of past points in a buffer for display purposes In addition to the information in this chapter you might find it helpful to study the graph and chart examples These examples are located in general examples general graphs G has three kinds of graphs and two kinds of charts These are shown in the following illustration starting at the top from left to right waveform chart waveform graph XY graph intensity chart and intensity graph F z RTS Al ke LS ool oe Foy Con To 25 1 National Instruments Corporation 15 1 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators Creating Waveform and XY Graphs You can obtain a waveform graph and XY graph from the Controls Graph palette Examples of these graphs are shown in the following illustration xand Y arrays Multi Plot 1 0 0 20 40 60 2000 The waveform graph plots only single valued functions with points that are evenly distributed with respect to the x axis such as acquired time varying waveforms The XY graph is a general purpose Cartesian graphing object you can use to plot multivalued functions such as circular shapes o
354. indicators It also explains how to import graphics from other programs to use in your controls Building the Front Panel Controls and indicators on the front panel are the interactive input and output terminals of the VI You use controls to supply data to a VI and indicators display the data generated by the VI This section explains a few editing options common to all controls and indicators The Controls palette on the front panel is shown in the following illustration If you idle your cursor over any square of the panel the name of the collection of controls is displayed The types of controls in the palette from left to right top to bottom are as follows e Numeric controls For entering and displaying numeric quantities e Boolean controls For entering and displaying TRUE FALSE values National Instruments Corporation 8 1 G Programming Reference Manual Chapter 8 Introduction to Front Panel Objects String amp Table controls For entering and displaying text List amp Ring controls For displaying and or selecting from a list of options Array amp Cluster controls For grouping sets of data Graph controls For plotting numeric data in chart or graph form Path amp Refnum controls For entering and displaying file paths and for passing refnums from one VI to another Decorations For adding graphics to customize front panels These objects are for decoration only and do not display da
355. ing 24 1 to 24 8 cooperative definition 24 1 execution system activities 24 2 mechanism of 24 1 to 24 2 task switching 24 2 to 24 3 preemptive 24 1 prioritizing tasks of same priority level 24 3 reentrant execution 24 5 examples 24 5 to 24 8 subroutine priority level 24 4 synchronous nodes 24 3 VI Setup priority setting 24 4 Wait functions for prioritizing tasks 24 3 multivalued slides 9 20 NaN not a number propagation by floating point operations 4 17 range errors note 4 18 native file dialogs using 7 22 Network Connection RefNum 12 4 12 5 node pop up menu See Hierarchy Node Pop Up menu nodes See also structures definition 16 1 functions 16 8 to 16 11 G Programming Reference Manual mouse click sequences for hierarchy node selection 3 21 to 3 22 overview 1 5 16 8 structures 16 11 to 16 12 nondisplayable characters See Backslash V Codes Display option non numeric data types table A 10 nonuniform scale markers See scale markers Normal Display option 11 3 not a number See NaN not a number Not a Path option 12 2 Not a Path symbol 12 2 Not OK button 22 3 numeric constants pop up menu 16 5 universal 16 7 user defined 16 4 numeric controls and indicators color box 9 24 color ramp 9 25 to 9 26 digital controls and indicators 9 2 to 9 11 changing representation of numeric values 9 4 to 9 5 digital numeric pop up menu options 9 3 displaying integers in other radixes
356. ing Reference Manual Chapter 15 Graph and Chart Controls and Indicators If you want to pass multiple points for plots in a single update you can wire an array of clusters of numerics to the chart Each numeric represents a single point for each of the plots An example of this is shown in the following illustration of points Waveform Chart If the number of plots you want to display cannot be determined until runtime or you want to pass multiple points for plots in a single update you can wire a two dimensional array of data to the chart As with the waveform graph rows are normally handled as new data for each plot G Programming Reference Manual 15 24 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators You can use the Transpose Array option of the waveform chart pop up menu to handle columns as new data for each plot Waveform Chart Options Number of Channels The chart has most of the same features as the graph including the legend and palette and they work the same way See the Scale Options and Legend Options sections of this chapter for more information The waveform chart does not have support for cursors The following illustration shows the chart pop up menu National Instruments Corporation Change to Control Find Show Data Operations Create kou Menige tipi Replace H Scale Y Scale TPEGBOSe Hiya Stack Plots Chart History Length 15 2
357. ing and transferring colors 2 26 customizing colors 2 25 to 2 26 foreground and background colors 2 25 limitations 2 24 transparent objects 2 24 to 2 25 columns headers 11 6 resizing 11 6 to 11 7 lt command gt key cutting copying and pasting icons note 3 4 moving between array elements 14 13 moving between cluster elements 14 21 G Programming Reference Manual l 22 Step Into button shortcut 4 20 Step Out button shortcut 4 20 Step Over button shortcut 4 20 lt command b gt removing bad wires 4 10 lt command click gt copying and transferring colors 2 26 lt command f gt bringing up Find dialog box 3 24 lt command h gt help key 1 7 lt command m gt switching from run mode to edit mode note 6 6 lt command Shift gt bringing up temporary Tools palette 2 4 lt command y gt calling History window 14 6 commenting out sections of diagrams 4 31 comments prompting for 6 4 7 18 to 7 19 recording comments generated by editor 7 19 Common Plots option 15 20 to 15 21 common questions about G See questions about G Communication option Functions menu 5 1 Complete Documentation format Print Documentation dialog box 5 4 25 9 complex double precision CDB 9 4 complex extended precision CXT 9 4 complex single precision CSG 9 5 conditional terminal 18 4 Configure option Call Library function 23 3 configuring G See Preferences dialog box connections for terminals See terminal conne
358. ing illustration and click on OK to save it This description appears when you subsequently choose Description from the pop up menu for the object Description Description Ambient temperature during calibration G Programming Reference Manual 2 26 National Instruments Corporation Chapter 2 Building Vis The description of the object also appears in the Help window when you place the cursor over the object The best way to set up help for the VIs you create is to enter descriptions for all your controls and indicators Note You cannot edit subVI descriptions from the calling VI diagram You can edit a VI description through the Windows Show VI Info option when the front panel of the VI is open Function description boxes are blank so that you can describe the action taking place at each occurrence of that function on the block diagram Creating VI Descriptions Selecting Windows Show VI Info displays the information dialog box for the current VI You can use the information dialog box to perform the following functions Saving VIs Enter a description of the VI The description window has a scrollbar so you can edit or view lengthy descriptions Lock or unlock the VI You can execute but not edit a locked VI View the current revision number View the path of the VI View how much memory the VI uses The Memory Usage portion of the information box displays the disk and system memory used by the VI T
359. ing options from the pop up menu next to this option all controls connected controls Descriptions Prints the descriptions next to the control names Include Data Type Information If you print to the printer then the terminal for each control is printed to the left of the control name If you save to a text file the data type is printed after the description Block Diagram Prints the block diagram Hidden Frames Prints the nonvisible frames of Case Structures and Sequence Structures Repeat Higher Level Frames When printing nonvisible frames prints the visible ones again in sequence VI Hierarchy Prints a description of the current VI hierarchy in memory with lines showing connections between VIs and their subVIs The current VI is highlighted with a box List of Sub VIs Prints the icon name and path of all subVIs used VI History Prints the history information if any for the current VI Printing Section Headers In addition to the layout options found in the Print Documentation dialog box the Custom Print Settings dialog box has a Print Section Headers option Print Section Headers Prints a header for each section for example a heading such as List of SubVIs before the subVI information When printing using Print Documentation this selection is set automatically for each format G Programming Reference Manual 5 6 National Instruments Corporation Chapter 5 Printing VIs Programmatic P
360. ing to or reading from a file Because strings and arrays are stored in handle blocks clusters containing these types are discontiguous In general data is stored in tree form For example a cluster of a double precision floating point number and a String is stored as an 8 byte floating point number followed by a 4 byte handle to the string The string data is not stored adjacent in memory to the extended precision floating point number Therefore if you want to write the cluster data to disk you have to get the data from two different places Of course with an arbitrarily complex data type the data might be stored in many different places When data is saved to a VI file or a datalog file it flattens the data into a single string before saving it This way even the data from an arbitrarily complex cluster is made contiguous instead of being stored in several pieces When G loads such a file from disk it must perform the reverse operation it must read a single string and unflatten it into its internal G form The flattened data is normalized to a standard form so that the data can be used unaltered by VIs running on any platform It stores numeric data in big endian form most significant byte format and it stores extended precision floating point numbers as 16 byte quantities using the Sun extended precision format described earlier in this section Similar transformations might be necessary when reading data written by other
361. ion 1 9 Help window 20 6 pop up menu 20 2 setting all attributes at one time 20 5 attributes 20 7 to 20 10 Active Plot 20 10 to 20 11 Blinking 20 8 to 20 9 Bounds read only 20 10 Disabled 20 7 to 20 8 Double Click 20 13 to 20 14 examples See Attribute Nodes Key Focus 20 8 Plot Color 20 10 to 20 11 Position 20 9 Auto Center option 6 5 auto indexing definition 18 7 For Loop count 18 8 While Loops 18 9 Automatic Update from Directory pop up option 7 28 Autoscale X option 15 13 Autoscale Y option 15 13 autosizing clusters 14 23 Autosizing option 14 23 Auto Update from Type Def option 22 21 background colors 2 25 Backslash V Codes Display option available codes table 11 4 tab characters in strings note 11 2 working in backslash mode 11 4 to 11 5 backslash character backslash V code table 11 4 lt Backspace gt key deleting objects 2 13 deleting wires 17 6 Bar Plots option 15 21 base attributes See attributes bends in wires 17 6 big endian data A 12 bitmap printing 7 17 black and white vs color icons 3 3 blinking background blinking color 7 14 foreground blinking color 7 14 setting blink speed of front panel objects 7 10 Blinking Attribute 20 8 to 20 9 Block Diagram option Custom Print Settings dialog box 5 6 Block Diagram Preferences dialog box 7 11 to 7 12 illustration 7 11 Show dots at wire junctions 7 11 Show subVI names when dropped 7 11 Show ti
362. ion but does present a dialog box to explain why In cases where there is only a potential problem a dialog box National Instruments Corporation 3 11 G Programming Reference Manual Chapter 3 Building SubVIs appears with an explanation of the potential problem You then must decide whether or not to continue Tip If there are no local variables or Attribute Nodes in a selection you might want to use a Sequence Structure to encapsulate the code you want sent to a subVI and preview the results The following rules and recommendations can help you use this G feature effectively Number of Connections Do not make very large selections that create a subVI with more than 28 inputs and outputs the maximum number of connections on a connector pane Keep in mind that each front panel terminal each attribute and certain local variables included in the selection require a slot in the connector pane a selection with a large number of these items might run out of connector pane slots To avoid exceeding the maximum terminals select a smaller section of the diagram or group data into arrays and clusters before selecting a region of the diagram to convert Cycles Try to avoid making selections that create cycles in the diagram Cycles occur if a data flow originates from an output of the subVI and terminates as an input to the subVI Identifying cycles while making selections is difficult but G detects them for you When G de
363. ire a number outside the range n to n 1 to the record terminal the invalid record output is set to TRUE and no data is retrieved Retrieving Data Using File 1 0 Functions You also can retrieve data that has been logged from the front panel of a VI using file I O functions that belong to G Each record in the datalog file created by front panel data logging is a cluster containing a time stamp It also contains a cluster of an unsigned 32 bit integer for seconds since G reference time as well as an unsigned 16 bit integer for additional milliseconds This integer is followed by a cluster of the front panel data in panel order You can access the records of datalog files created by front panel data logging using the same G file I O functions that you use to access programmatically created datalog files Enter the appropriate type described previously as the type input to the File Open function as shown in the following example data log path ront panel data National Instruments Corporation 4 9 G Programming Reference Manual Chapter 4 Executing and Debugging VIs and SubVIs Debugging Vis Debugging Broken VIs A VI cannot compile or run if it is broken The VI Run button typically appears broken while you are creating or editing it until you wire all the icons in the diagram If it still is broken after you finish wiring the icons try selecting Edit gt Remove Bad Wires or selecting lt Ctrl b gt
364. is You must remove unused shift registers Right Shift Register some but not all left sides are wired A shift register must have inputs for all the left sides or for none Sequence locals were never assigned One or more sequence You forgot to wire to a Sequence Structure local variable Remove unused sequence locals subVI name bad linkage to subVI The connector pattern of the subVI changed since you last loaded the subVI or you forgot to assign controls or indicators of the subVI to connector terminals In the former case you can use the Relink command in the subVI pop up menu G Programming Reference Manual 4 12 National Instruments Corporation Table 4 1 Chapter 4 Executing and Debugging VIs and SubVIs Error Messages Continued Error Messages Descriptions subVI nam recursive references dispose it You have changed the name of the calling VI to be the same as one of its subVIs and now G registers this change as the VI calling itself recursively The VI and subVI are probably in different directories G prevents recursion when you attempt to place a VI on its own block diagram subVI name LV Subroutine link error A problem exists with linkage to a CIN routine subVI name A Subroutine priority VI cannot call a non subroutine priority subVI subVI name running subVI is already You must make the subVI execute at subroutine
365. is a 24 hour information retrieval system containing a library of documents on a wide range of technical information You can access FaxBack from a touch tone telephone at 512 418 1111 E Mail Support currently U S only You can submit technical support questions to the appropriate applications engineering team through e mail at the Internet addresses listed below Remember to include your name address and phone number so we can contact you with solutions and suggestions BridgeVIEW bv support natinst com DAQ daq support natinst com Fax and Telephone Support National Instruments has branch offices all over the world Use the list below to find the technical support number for your country If there is no National Instruments office in your country contact the source from which you purchased your software to obtain support Australia Austria Belgium Canada Ontario Canada Quebec Denmark Finland France Germany Hong Kong Israel Italy Japan Korea Mexico Netherlands Norway Singapore Spain Sweden Switzerland Taiwan U K es 03 9879 5166 0662 45 79 90 0 02 757 00 20 905 785 0085 514 694 8521 45 76 26 00 90 527 2321 01 48 14 24 24 089 741 31 30 2645 3186 03 5734815 02 413091 03 5472 2970 02 596 7456 95 800 010 0793 0348 433466 32 84 84 00 2265886 91 640 0085 08 730 49 70 056 200 51 51 02 377 1200 01635 523545 lt A Telephone LabVIEW lv support natinst com lookout support natinst
366. is shown in the following illustration 10 Array Control 10 Array Control If you now select Reinitialize to Default from either the shell or the index pop up menus the array reverts to the 10 element array shown in the previous example To increase the size of an array from Nj by Nj by Nk to Mj by Mj by Mk assign a value to the new last element Mj 1 Mj 1 Mx 1 To decrease the size first execute the Data Operations Empty Array command from the index array pop up menu then set the array and values to the size you want or select the unwanted subset of the array and select the Data Operations Cut Data option from the pop up menu as explained in the following sections Array Elements When in run mode you can use the lt Tab gt key either to move the key focus between front panel controls or between elements within a single array Initially the lt Tab gt key moves the key focus between front panel controls To have it move between the elements within a specific array first lt Tab gt to that array Then use the lt Ct r1 gt Windows lt command gt Macintosh lt met a gt Sun or lt Alt gt HP UX key and the down arrow which you can use to move between the array elements If you want to return to tabbing between controls use the lt Ctr1 gt Windows lt command gt Macintosh lt met a gt Sun or lt Alt gt HP UX key and the up arrow Finding the Size of Arrays To find the si
367. isks creating a conflict during future installations If you want your VIs to show up in the Functions palette see the Customizing the Controls and Functions Palettes section in Chapter 7 Customizing Your G Environment for more information VI Libraries LLBs You can group several VIs together and save them as a VI library However unless you have a good reason for saving them as libraries it is preferable to save them as individual files organized in directories Read the following lists before deciding to save VIs in a library Reasons for you to save VIs as libraries e Ifyou are using Microsoft Windows 3 1 or plan to transfer your files to Windows 3 1 saving VIs as libraries allows you to use up to 255 characters to name your files Other operating systems have long filename support 31 characters on the Macintosh 255 characters on Windows 95 NT and UNIX systems e Ifyou are going to transfer VIs to other platforms transferring a VI library is easier than transferring multiple individual VIs e If disk space is an important issue you can save your files within VI libraries because they are compressed slightly reducing disk space requirements for VIs Reasons for you to save VIs as individual files e Ifyou store your VIs as individual files you can use the file system to manage them copying moving renaming backing up managing source code e You cannot have hierarchy within a VI library VI libraries cannot
368. isting wire The wire blinks when the Wiring tool is correctly positioned to fasten a new wire to the existing wire You can wire directly from a terminal outside a structure to a terminal within the structure using the basic wiring operation G creates a tunnel where the wire crosses the structure boundary as shown in the following illustration Wires unwind from terminals vertically or horizontally depending on the direction in which you first move the Wiring tool Wires move vertically if you move the tool up or down and they move horizontally if you move the tool left or right The connection is centered on the G Programming Reference Manual 17 2 National Instruments Corporation Chapter 17 Wiring the Block Diagram terminals regardless of the exact position of the hot spot when you click the mouse button on it as shown in the following illustration You can bend your wire s at a ninety degree angle once without clicking on it You click on the mouse to tack the wire and change direction as shown in the following illustration Note You also can change between horizontal and vertical directions by pressing the spacebar You can untack the last tack point by pressing lt Ctrl click gt Windows lt option click gt Macintosh lt meta click gt Sun lt Alt click gt HP UX If the last tack point is the terminal or wire on which you first clicked untacking removes the wire completely National Instruments
369. items common to other applications such as Open Save Copy and Paste and many others specific to the language G Some menus also list shortcut key combinations The menu in G that you use most often is the object pop up menu Almost every G object as well as empty front panel and block diagram space has a pop up menu with options and commands Instructions throughout this manual suggest that you select a command or option from an object pop up menu Pop Up Menus As you learned in the previous section all G objects have associated pop up menus You pop up on an object by clicking on the object with the right mouse button on the Macintosh holding down the lt command gt key while you click on the object with the mouse By selecting options from the resulting menu you can access options related to that object and change its look or behavior Change to Indicator Find Terminal Label Data Operations Unit Label Key Navigation Replace Representation Data Range Format amp Precision Add Needle Scale Text Labels G Programming Reference Manual 2 6 National Instruments Corporation Chapter 2 Building Vis Editing VIs After you are familiar with editing techniques see the Front Panel Objects section Chapters 8 through 15 for information on building front panels and the Block Diagram Programming section of this manual Chapters 16 through 21 for help in building block diagrams Selecting Objects
370. ize Mode option 22 5 to 22 6 Change to Edit Mode option 22 5 to 22 6 Change to Indicator option 8 3 14 20 17 13 Change to Input option 19 4 Change to Output option 19 4 Change to Read Global option 21 3 Change to Read Local option 21 4 Change to Read option 20 2 to 20 3 Change to Write Global option 21 3 Change to Write Local option 21 4 Change to Write option 20 2 Changed VIs option 25 4 Chart History Length option 15 26 15 40 chart indicators attributes Active Plot 20 10 to 20 11 Plot Color 20 10 to 20 11 intensity chart 15 36 to 15 41 defining color mapping 15 40 to 15 41 illustrations 15 37 to 15 38 pop up menu 15 39 questions about B 1 to B 4 waveform chart 15 22 to 15 29 data types 15 22 to 15 25 options 15 25 to 15 29 stacked versus overlaid plots 15 28 to 15 29 update modes 15 26 to 15 28 CINs Code Interface Nodes 23 2 Clear Breakpoint cursor 4 26 Clear Log File Binding option Operate menu 4 6 Clear option Edit menu 2 13 cloning objects 2 13 Close Afterwards if Originally Closed option 6 2 National Instruments Corporation Index Cluster Order option 4 16 14 22 cluster shell 14 20 Cluster Size option 14 28 Cluster To Array function 14 32 to 14 33 clusters 14 19 to 14 33 assembling 14 23 to 14 29 Array To Cluster function 14 28 to 14 29 Bundle By Name function 14 24 to 14 28 Bundle function 14 24 autosizing 14 23 cluster order A 5 compared with arrays 14 19 c
371. jects 2 11 to 2 12 coloring objects 2 24 to 2 26 creating object descriptions 2 26 to 2 27 creating VI descriptions 2 26 to 2 27 deleting objects 2 13 distributing objects 2 12 dragging and dropping VIs pictures and text 2 8 to 2 9 duplicating objects 2 12 to 2 13 G Programming Reference Manual Index G environment 2 1 to 2 6 menus 2 6 pop up menus 2 6 switching to Basic G palette from Bridge VIEW note 2 1 Tools palette 2 4 to 2 5 labeling objects 2 14 to 2 22 free labels 2 14 to 2 16 text characteristics 2 16 to 2 22 positioning front panel and block diagram side by side 2 3 positioning objects 2 9 to 2 11 resizing objects 2 23 front panel and block diagram work space 2 24 labels 2 23 to 2 24 saving VIs 2 27 to 2 30 individual VI files 2 28 to 2 29 VI libraries LLBs 2 29 to 2 30 selecting objects 2 7 to 2 8 from palettes 2 1 to 2 4 multiple selection with selection rectangle 2 7 to 2 8 lt Shift gt clicking 2 7 2 8 terminals created automatically with front panel object 2 3 to 2 4 bulletin board support C 1 Bundle By Name function accessing cluster elements 22 22 assembling clusters 14 24 to 14 28 Bundle function 14 24 byte integer numeric data storage format A 3 Byte Stream File RefNum 12 5 C Call Chain ring 4 21 Call Chains reading 4 21 Call Library Function 23 3 to 23 7 Call Library Function dialog box 23 4 calling conventions Windows 23 4
372. ken until you create the correct number of output terminals When the number of terminals is correct the wire National Instruments Corporation 14 29 G Programming Reference Manual Chapter 14 Array and Cluster Controls and Indicators becomes solid The terminal symbols display the element data types as shown in the following illustration Unbundle By Name Function eI The Unbundle By Name function also in the Array amp Cluster palette Unbundle By Name of the Functions palette is similar to the Unbundle function Instead of function referencing fields by position however you reference them by name Unlike the Unbundle function you can read only the elements that you want to read you do not have to have one output for every cluster element For example the following is a panel with a cluster of three elements weight height and age When connected to an Unbundle By Name function you can pop up on an output terminal of the function and select an element that you want to read from the names of the components of the cluster as shown in the following illustration G Programming Reference Manual 14 30 National Instruments Corporation Chapter 14 Array and Cluster Controls and Indicators You can resize the function to read other elements shown in the following illustration Keep in that you do not have to read all of the elements and that you can read them in arbitrary order One of the advantages of the
373. king on an unselected object or clicking on an open area deselects everything currently selected lt Shift gt clicking on an object selects or deselects it without affecting other selected objects You cannot select a front panel object and a block diagram object at the same time However you can select more than one object on the same front panel or block diagram Dragging and Dropping VIs Pictures and Text in G You can drag VIs from the file system to a block diagram to create a subVI call to that VI This feature also works for custom controls type definitions and globals In addition you can drag text and pictures from other applications to copy them to front panels and block diagrams In Windows 3 1 external drag support is limited to dragging VIs and controls from the File Manager In Windows 95 NT which have 32 bit object linking and embedding OLE support you can drag text and pictures from OLE supporting applications in addition to dragging from the File Manager Explorer On the Macintosh your system must have the Drag Manager to use external Drag and Drop The Drag Manager is built into Systems 7 5 and later It is also available for System 7 0 up to System 7 5 as an extension from Apple You can use the following Drag and Drop capabilities internally between various G objects e Drag front panel controls and indicators to block diagrams to create block diagram constants and vice versa e Drag asubVI to a path
374. kpoint tool in the Tools palette and then click on the block diagram node or wire Click this tool on the same object at any time to remove the breakpoint The appearance of the tool indicates if a breakpoint is set or cleared as shown at the left The following table indicates how breakpoints are displayed and when execution pauses in relation to where breakpoints are placed Table 4 2 Breakpoint Placement Location of How Breakpoint Is When Pause Will Occur Breakpoint Highlighted Block diagram Red border around block When the end of the block diagram If the diagram is diagram is reached inside a structure the red border is inside the structure as well Node Red border framing the Just before the node node executes At this point all the input signals into the node can be probed with the Probe tool Wire Red bullet in the middle After data has passed of wire If a probe is through the wire attached to the wire the probe has a red border National Instruments Corporation 4 27 G Programming Reference Manual Chapter 4 Executing and Debugging VIs and SubVIs In the following example the wire with the attached probe has a breakpoint The VI pauses after the probe has generated data O Probe 2 E Probe 2 1 0000E 0 In the next example the Increment node has a breakpoint The VI pauses before Increment executes One wire also has a breakpoint The VI pauses after M
375. l Operating tool P palette pixmap platform plot polymorphism pop up pop up menus Positioning tool probe G Programming Reference Manual Front panel objects used to manipulate and display or input and output numeric data Generic term for any item on the front panel or block diagram including controls nodes wires and imported pictures Tool used to access the pop up menu for an object Having one dimension as in the case of an array that has only rows Tool used to enter data into controls as well as operate them Resembles a pointing finger Menu of pictures that represent possible options A standard format for storing pictures in which each pixel is represented by a color value A bitmap is a black and white version of a pixmap Computer and operating system A graphical representation of an array of data shown either on a graph or a chart Ability of a node to automatically adjust to data of different representation type or structure To call up a special menu by clicking on an object with the right mouse button on Window Sun and HP UX or while holding down the command key on the Macintosh Menus accessed by popping up usually on an object Menu options pertain to that object specifically Tool used to move select and resize objects Debugging feature for checking intermediate values in a VI G 10 National Instruments Corporation Probe tool programmatic printin
376. l LJ Parameter return type H zh Type Void Add a Parameter After Function Prototype oid funcName void As you select options in the dialog box an indicator at the bottom called Function Prototype displays the C prototype for the selected function cz Note In Windows 3 1 an upper limit of 29 4 byte arguments can be passed using the Call Library Function Double precision floating point parameters passed by value are 8 byte quantities and therefore count as two arguments Thus you are limited to 14 double precision floating point parameters passed by value i Note In Windows 3 1 DLLs must be 16 bit In Windows 95 NT DLLs must be 32 bit If you have a 16 bit DLL that you want to call from Windows 95 NT you either must recompile it as a 32 bit DLL or create a thunking DLL Refer to Microsoft documentation for information on thunking DLLs Calling Conventions Windows Use the calling conventions of the ring to select the calling conventions for the function The default calling convention for Windows 3 1 is Pascal and Standard C for Windows 95 NT This default corresponds to the calling convention that is used by most DLLs The alternative G Programming Reference Manual 23 4 National Instruments Corporation Chapter 23 Calling Code from Other Languages option is to use C calling conventions Refer to the documentation for the DLL you are trying to call to determine whic
377. l You can think of tunnels as way Stations for data flowing into or out of a structure Depending upon the type of structure the data can be transformed by the tunnels Structures also have other terminals that are particular to each type of structure These terminals are described with the appropriate structures in the following sections For Loop and While Loop Structures You use the For Loop and While Loop to control repetitive operations either until a specified number of iterations has completed For Loop or until a specified condition is no longer true While Loop For Loop A For Loop executes its subdiagram count times where the count equals the value contained in the count terminal You can set the count N explicitly by wiring a value from outside the loop to the left or top side of the count terminal or you can set the count implicitly with auto indexing see the Auto Indexing section in this chapter for more information The other edges of the count terminal are exposed to the inside of the loop so you can access the count internally count terminal N The iteration terminal contains the current number of completed iterations 0 during the first iteration 1 during the second and so on up to N 1 Both the count and iteration terminals are signed long integers with a range of 0 through oP 1 Tt you wire a floating point i number to the count terminal G rounds it off if necessary and coerces it to within th
378. l Instruments solve your technical problems and a form you can use to comment on the product documentation e The Glossary contains an alphabetical list and description of terms used in this manual e The ndex contains an alphabetical list of key terms and topics in this manual including the page where you can find each one Conventions Used in This Manual bold italic bold italic monospace italic monospace lt gt The following conventions are used in this manual Bold text denotes menus palettes menu items or dialog box buttons or options In addition bold text denotes VI input and output parameters Italic text denotes emphasis a cross reference or an introduction to a key concept Bold italic text denotes a note caution or warning Monospace font denotes text or characters that you enter using the keyboard Sections of code programming examples syntax examples key names and messages and responses that the computer automatically prints to the screen also appear in this font Italic text in this font denotes that you must supply the appropriate words or values in the place of these items Angle brackets enclose the name of a key on the keyboard for example lt Shift gt A hyphen between two or more key names enclosed in angle brackets denotes that you should simultaneously press the named keys for example lt Shift Delete gt The symbol leads you through nested menu items
379. l order to the number displayed inside the Tools palette You can change this number by typing a new number into it When the panel order is the way you want it click on the Enter button to set it and exit the panel order edit mode Click on the X button to revert to the old panel order and exit the panel order edit mode X Button The panel order determines the order in which the controls and indicators appear in the records of datalog files produced by logging the front panel Customizing Dialog Box Controls There are several types of dialog box controls dialog rings which are numeric dialog buttons which are Boolean dialog checkmarks and dialog buttons Dlg Ring dialog ring dialog button The dialog controls change appearance depending on which platform you are using Each appears with the color and appearance typical of that platform National Instruments Corporation 8 9 G Programming Reference Manual Chapter 8 Introduction to Front Panel Objects Windows The dialog button appears as a three dimensional rectangular gray button The dialog ring appears as a flat black and white rectangle as shown in the following illustration Macintosh The dialog button appears as a two dimensional black and white oval The dialog ring appears as a black and white rectangle with a drop shadow as shown in the following illustration UNIX The dialog button appears as a three dimensional rectangular gray button The dialog
380. l value However if you do not initialize the shift register the output is either the default value for the data type 0 FALSE or empty string or the output is the last value loaded into the shift register when the diagram last executed Indexing beyond the bounds of an array produces the default value for the array element data type You can do this inadvertently in a number of ways such as indexing an array past the last element using a While Loop supplying too large a value to the index input of an Index Array function or supplying an empty array to an Index Array function When you design VIs that can produce undefined output values for certain input values you should not rely on special values such as NaN or empty arrays to identify the problem Instead make sure your VI either produces an error message that identifies the problem or produces only defined default data For example if you create a VI that uses an incoming array to auto index a For Loop you need to evaluate the operation of the VI if National Instruments Corporation 4 17 G Programming Reference Manual Chapter 4 Executing and Debugging VIs and SubVIs i Note the input array is empty You either can produce an output error code or substitute predefined values for the values created by the loop A floating point indicator or control with a range of Infinity to Infinity still can generate a range error if you send NaN to it Understanding Warnings
381. le a graph To print only a graph from the front panel create a subVI with a graph on its front panel 1 Change the graph from an indicator to a control 2 Open the subVI and select Operate Print at Completion 3 Assign the subVI a connector and pass the data from the graph on the main VI to the graph on the subVI Every time your main VI calls the subVI it automatically prints the graph How can print a string Use the Serial Port Init vi to initialize the port where the printer is connected LPT1 LPT2 and so on on the PC or the printer port on the Mac and then the Serial Port Write vi to write the string to the initialized port The printer sees the data at the port and prints it Doing this generally requires some knowledge of the command language of your printer but has worked well for a number of applications developed by LabVIEW and Bridge VIEW users If you are a LabVIEW user see Appendix C Serial I O Common Questions as well as Chapter 8 Serial Port VI s of the LabVIEW Instrument I O VI Reference Manual for more details National Instruments Corporation B 7 G Programming Reference Manual Appendix B Common Questions about G Windows and UNIX Use the System Exec VI to print a file through a command line function The VI is located in Functions Communication AppleEvent For more details see the section Using Alternative Printing Methods in Chapter 5 Printing VIs You also can use the programmatic
382. le you could import pictures of an open and closed valve for a Boolean switch If there is not a current picture on the Clipboard Import Picture is disabled 22 10 National Instruments Corporation Chapter 22 Custom Controls and Type Definitions There is a shortcut in the Control Editor for importing pictures into a Boolean control When you are in edit mode you do not have to be in customize mode you can select Import Picture True or Import Picture False from the pop up menu of a Boolean Doing this imports the picture into both the normal state and the corresponding transition state You also can import different pictures for the transition states in customize mode To do this first pop up on the button and use Picture Item to change the third picture With the True False picture on the Clipboard pop up again and select Import Picture Repeat these steps for the fourth False True picture e Import at Same Size Replaces the current picture but keeps the original size of the part shrinking or enlarging the Clipboard picture to fit If there is not a current picture on the Clipboard Import at Same Size is disabled e Revert Restores the part to its original appearance Revert does not change the position of the part If you opened the Control Editor window by selecting Edit Control from a front panel the editor reverts the part to the way it looks on that front panel If you opened the Control Editor window by selectin
383. le RefNum Out front panel block diagram The following illustration shows the front panel and block diagram of a VI that uses and returns a Data Log File RefNum generated in another VI Datalog files can contain any data type The datalog file in the following example contains numeric data Data Log File Data Log File Data Log File Data Log File RefNum In RefNum Out RefNum Out front panel block diagram The following illustration shows the front panel and block diagram of a VI that uses and returns a Network Connection RefNum generated in another VI Net Conn Net Conn Net Conn Net Conn RefNum In RefNum Out RefNum In RefNum Out TCP front panel block diagram National Instruments Corporation 12 5 G Programming Reference Manual Chapter List and Ring Controls and Indicators This chapter describes the listbox and ring controls and indicators which are available from the Controls List amp Ring palette shown in the following illustration a The List amp Ring palette contains eight controls Text Ring Menu Ring Dialog Ring Pict Ring Text amp Pict Ring Single Selection Listbox Multiple Selection Listbox and Enumerated Type This chapter discusses the ring controls listbox controls and the enumerated type controls in that order For information about the attributes of listbox and ring controls see Chapter 20 Attribute Nodes Listbox Controls Listbox c
384. leEvent In Windows you also can use dynamic data exchange DDE to tell another application to print data Printing Configuration There are two dialog boxes that affect the appearance of all printouts regardless of the method you use to print the Printing dialog box and the Preferences dialog box You use the Printing dialog box of the Preferences dialog box to tell G how it should print You can choose the following dialog box for example to implement PostScript printing National Instruments Corporation 5 1 G Programming Reference Manual Chapter 5 Printing VIs To configure information and formatting that is printer specific use the Printer Setup Page Setup in UNIX and on the Macintosh option from the File menu For example with most printers you change the orientation of printouts landscape versus portrait using this dialog box Many printers also have options for font substitution paper size and other printer specific settings Printer Setup Page Setup for the Macintosh and UNIX settings are saved with your VI PostScript Printing To produce higher quality printouts you can use the Preferences dialog box which contains options for customizing the way G prints including the option to select PostScript printing if you have a PostScript printer If you have a PostScript printer you can take advantage of the following benefits e PostScript printouts reproduce the image of the screen more accur
385. ling Objects Labels are blocks of text that annotate components of front panels and block diagrams There are two kinds of labels owned labels and free labels Owned labels belong to and move with a particular object and annotate that object only You can hide these labels but you cannot copy or delete them independently of their owners Free labels are not attached to any object and you can create move or dispose of them independently Use them to annotate your front panels and block diagrams You use the Labeling tool whose cursor is the I beam and box cursor to create free labels or to edit either type of label Free Labels To create a free label select the Labeling tool from the Tools palette and click anywhere on the open space A small box appears with a text cursor at the left margin ready to accept typed input Type the text you want to appear in the label As shown in the following illustration the Enter button appears on the toolbar to remind you to end text entry by clicking on the Enter button Model 704 Meter You also can end text entry by pressing the lt Enter gt key on the numeric keypad If you do not have a keypad you can press the lt Enter gt Windows and HP UX or lt Return gt Macintosh and Sun key on the keyboard or click anywhere outside the label If you do not type any text in the label the label disappears as soon as you click on any other area G Programming Reference Manual 2 14
386. lobals button 3 19 Include Globals option 3 18 Include Type Definitions button 3 19 Include Type Defs option 3 19 Include VI Lib button 3 19 Include VIs in vi 1ib option 3 18 independent parts 22 6 to 22 7 Independent Sizes option 22 14 Index Array function icon 14 17 index display for arrays array shell 14 5 displaying array in single element or tabular form 14 9 to 14 11 interpreting 14 8 to 14 9 pop up menu 14 7 Index Display option 14 11 index for arrays 14 1 to 14 2 indicators See controls and indicators G Programming Reference Manual Inf propagation by floating point operations 4 17 range errors note 4 18 info Labview user group B 9 to B 10 input output performance considerations 26 6 to 26 7 Insert option wire pop up menu 16 12 Insert Submenu dialog box 7 27 to 7 29 Automatic Update From directory 7 28 Create a new menu file 7 28 illustration 7 28 Link to a directory 7 28 Link to a library 7 28 Link to an existing menu file 7 28 inserting block diagram objects 16 12 instr lib adding VIs and controls 7 25 integers displaying in other radixes 9 4 intensity charts 15 36 to 15 41 illustrations 15 37 to 15 38 options 15 38 to 15 41 color mapping 15 40 to 15 41 history of data 15 40 pop up menu 15 39 intensity graph 15 29 to 15 30 data type 15 29 options 15 29 to 15 30 Interpolate Colors option 9 25 Interpolation option 15 21 to 15 22 interrupts servicing
387. lock diagram of another VI first create an icon and connector for it This section explains how to create and edit a VI icon and connector National Instruments Corporation 3 1 G Programming Reference Manual Chapter 3 Building SubVis Creating the Icon To create an icon make sure you are in edit mode Either double click on the icon in the top right corner of the front panel or pop up on the icon and select Edit Icon as shown in the following illustration Remember you must be in edit mode in the front panel window to get this menu _ Edit Icon Show Connector Paiiaayg Rpinip GO begrees Filo Horicon tad Eiir Phar die ai Eamgriviad i RH Terminnis EERGacegyayeced i Fina Fap yepbye ai Phas Canpa ipn ig After you select Edit Icon the Icon Editor appears Icon Editor Copy from 16 Colors iP rben EA EiS Terminala 256 Colors E G Programming Reference Manual 3 2 National Instruments Corporation Chapter 3 Building SubVis Use the tools to the left of the window shown in the preceding illustration to create the icon design in the fat pixel editing area The normal size image of the icon appears in the appropriate box to the right of the editing area Depending on the type of monitor you are using you can design a separate icon for display in monochrome 16 color and 256 color mode You design and save each icon version separately The editor defaults to
388. lor tool or the Operating tool and choosing the color you want from the Color palette The listbox symbol ring constant is used to assign symbols to items in a listbox control The error ring constant is a predefined ring You click on the constant with the Operating tool and select the error message you want from the dialog box that appears which is shown in the following illustration This ring is useful with the file I O functions because it makes the diagrams more descriptive For example if you try to open a nonexistent file using the Open File function the function returns an error code of 7 You can test for this condition by comparing the error code output to an error ring set to a value of File Not Found 7 G Programming Reference Manual 16 6 National Instruments Corporation Chapter 16 Introduction to the Block Diagram No error ol vf Mo error Argument error Memory iz full Dut of zone End of file File already open Generic file 10 error File not found File permission error Disk ts full Duplicate path Too many files oper System feature not enabled You can use the path constant to create a constant path value on the block diagram The path string and color box constants are resizable yet the Boolean numeric ring and enumeration constants are not The default representation of the numeric constant is a double precision floating point number if you enter a floating point number a long integer if y
389. lthough the Add command adds a terminal immediately after it The full names of these commands vary with the function Show Description Replace Change to Array Add Element Input Add Array Input Remove Input Structures When you are programming you sometimes need to repeat sections of code a set number of times or while a certain condition is true In other situations you need to execute different sections of code when different conditions exist or execute code in a specific order G contains four special nodes called structures They help you to control code execution which otherwise is not possible within the G dataflow framework Each structure has a distinctive resizable border that you use to enclose the code that executes under the structure s special rules For this reason the diagram inside the structure border is called a subdiagram You can nest subdiagrams G uses the following structures to execute code e For Loop Repeats execution a set number of times e While Loop Repeats the execution of its subdiagram while a condition is TRUE e Case Structure Contains multiple subdiagrams only one of which executes depending on the value passed to its selector terminal e Sequence Structure Executes code in the numeric order of its subdiagrams National Instruments Corporation 16 11 G Programming Reference Manual Chapter 16 Introduction to the Block Diagram Because structures are nodes they have
390. lue These controls include a vertical slide a horizontal slide the tank and the thermometer Using the Fill Options item in the pop up menu you can turn all slides into fill slides and you can turn fill slides into regular slides Normally you have three choices as shown in the following illustration These are fill from the minimum value to the slider location fill from the maximum value to the slider location or use no fill You also can show more than one value on the same slide To do so choose Add Slider from the pop up menu A new slider appears along with a new digital display as shown in the following illustration When you do this two more options appear in the Fill Options palette Fill to Value Above and Fill to Value Below These options apply to the active slider All five options appear in the following illustration 10 05 Te Peo 10 05 so Wt 50 o i 50 dd d d d d For an example of slide controls and indicators see general controls alarmsld 1lb G Programming Reference Manual 9 20 National Instruments Corporation Chapter 9 Numeric Controls and Indicators Rotary Numeric Controls and Indicators The rotary numeric controls and indicators are shown in the following illustration Za P 3 oO tax ts 5 faz faz Q 0 0 10 0 0 0 10 0 T T National Instruments Corporation 9 21 G Programming Reference Manual Chapter 9 Numeric Controls and Indica
391. matic Suspension A VI is suspended automatically if during its execution a control or an indicator goes out of range The terminal or local variable that caused the out of range error is selected A subVI with a control or indicator set to stop on a range error has a conditional breakpoint If a range error occurs the subVI pauses as if it National Instruments Corporation 4 29 G Programming Reference Manual Chapter 4 Executing and Debugging VIs and SubVIs encountered a breakpoint If no range error occurs the subVI executes normally When data passed to a subVI causes a range error the front panel of the subVI opens or comes to the foreground and the subVI remains in suspend mode At this time the values on the subVI controls are the inputs passed by the calling VI and you can change the values if you want In fact you must change them to run the subVI if the range error indicator is on The indicators of the subVI display either default values or values from the last execution of the subVI during which its front panel was open Using Toolbar Buttons When SubVis Are Suspended If you want to execute the current subVI before returning to the caller press the Run button or select the Operate Run command while in Run button suspend mode You can repeat the execution as many times as you want When the subVI completes the indicators display results from that execution of the subVI However you can change the indicator value
392. me and select the Data Operations Make Current Value Default command from the cluster pop up menu To reset all elements to their individual default configurations select the Data Operations Reinitialize To Default Values command from the cluster pop up menu To change the default value of a single element in a cluster pop up on that particular element and select Make Current Value Default Cluster Element Order Cluster elements have a logical order that is unrelated to their positions within the shell The first object you insert in the cluster is element 0 the second is 1 and so on If you delete an element the order adjusts automatically You can change the current order by selecting the National Instruments Corporation 14 21 G Programming Reference Manual Chapter 14 Array and Cluster Controls and Indicators a Enter button X button Cluster Order option from the cluster pop up menu The appearance of the element changes as shown in the following illustration Click to set toi Cluster of Controls in order current place in order The white boxes on the elements show their current places in the cluster order The black boxes show the new position of the element in the order Clicking on an element with the cluster order cursor sets the position of the element in the cluster order to the number displayed inside the Tools palette Change this order by typing a new number into that field When the order is as
393. me or date or both If you enter only time or only date G infers the unspecified components If you do not enter time G assumes 12 00 a m If you do not enter date it assumes the previous date value If you enter date but the control is not in a date G Programming Reference Manual 9 10 National Instruments Corporation Chapter 9 Numeric Controls and Indicators format G assumes the month day and year ordering based on the settings in the Preferences dialog box If you enter only two digits for the year G assumes the following any number less than 38 is in the twenty first century otherwise the number is in the twentieth century Though absolute time is displayed as a time and date string it is represented internally as the number of seconds since 12 00 a m Jan 1 1904 Universal Time G keeps track of these components internally Note When a control is in absolute time format you always have the option to enter time date or time and date If you do not want G to assume a date use relative time Notice the examples at the top right of the dialog box which change as you make selections The valid range for time and date differs across computer platforms as follows Windows 12 00 a m Jan 2 1970 12 00 a m Feb 4 2106 Windows NT 12 00 a m Jan 2 1970 12 00 a m Jan 17 2038 Macintosh 12 00 a m Jan 2 1904 12 00 a m Jan 2 2040 UNIX 12 00 a m Dec 15 1901 12 00 a m Jan 17 2038 T
394. ments See the Replacing Cluster Elements section in this chapter for an example of using this function to replace elements in a cluster Bundle By Name Function The Bundle By Name function also in the Functions Cluster palette is similar to the Bundle function Instead of referencing fields by position however you reference them by name Unlike the Bundle function you can access only the elements that you want to access For each element you want to access you need to add an input to the function G Programming Reference Manual 14 24 National Instruments Corporation Chapter 14 Array and Cluster Controls and Indicators Because the name does not denote a position within the cluster you must wire a cluster to the middle terminal as well You can use the Bundle By Name function only to replace elements by name not to create a new cluster You might however wire a data type cluster to the middle terminal and then wire all of the new values as names to produce this same behavior For example suppose you have a cluster containing a string called Name and a number called Age After placing the Bundle By Name function you first need to connect an input cluster to the middle terminal of the Bundle By Name function After you have wired the middle terminal you can select elements you want to modify by popping up on any of the left terminals of the Bundle By Name function You then see a list of the names of the elements in t
395. ments Corporation Chapter 2 Building Vis Font Dialog tol Application Font System Font Dialog Font Current Font Algerian Arial Arial Black Smaller Ctrl Arial Narrow Larger Ctrl Arial Rounded MT Bold Book Antiqua Font selections made from any of these submenus apply to objects you select For example if you select a new font while you have a knob and a graph selected the labels scales and digital displays all change to the National Instruments Corporation 2 19 G Programming Reference Manual Chapter 2 Building Vis new font The following illustration shows a numeric and a Boolean control being changed from the current font to the System font G Programming Reference Manual Diagram Default Font x Font _ System Ly sie E Align Lett Ea Color as he quick brown fox jumps over the lazy dog C Panel Default Diagram Default Plain O Bold O italic O Underline O Strikeout C Outline O Shadow 2 20 National Instruments Corporation Chapter 2 Building Vis G preserves as many font attributes as possible when you make a change If you change several objects to Courier font the objects retain their size and styles if possible In the same way changing the size of multiple text selections does not cause the selections to have the same font These rules do not apply if you select one of the predefined fonts the current font or when you use the Font dialo
396. ments at the source and destination points Although G detects data type and cluster size mismatches at edit time G does not detect mismatches of elements of the same type Use the Cluster Order option on the cluster shell pop up menu to check cluster order Check the node execution order Nodes that are not connected by a wire can execute in any order The spatial arrangement of these nodes does not control the order That is unconnected nodes do not execute from left to right top to bottom on the diagram as statements do in textual languages Check that there are not any extraneous VIs Unlike functions unwired subVIs do not always generate errors unless you configure an input to be required or recommended If you mistakenly place an unwired subVI on the block diagram it executes when the diagram does and consequently your program might end up doing extra actions Check that you do not have hidden VIs You inadvertently might have hidden subVIs three ways by dropping one directly on top of another node by decreasing the size of a structure without keeping the subVI in view or by placing one off the main diagram area In the last case scroll the block diagram window to its limits Also check the inventory of subVIs used in the VI against the Project menu options This VI s SubVIs and Unopened SubVIs to determine if any extraneous subVIs exist You also can look in the Hierarchy window to see the subVIs for a VI or in the Error
397. menu Copy Icon Empty Slot Edit Submenu Icon Empty Row Rename Submenu Control Option Synchronize with Director With the pop up options you can modify anything within the User Libraries menu corresponds to user 1ib or the Instrument I O menu corresponds to inst r 1ib If you want to edit the top level Controls or Functions palettes or any of the other predefined menus G Programming Reference Manual 7 26 National Instruments Corporation Chapter 7 Customizing Your G Environment you must first create a new view by selecting new setup from the menu setup ring in the Edit Palettes dialog box After selecting a new setup any menu that you modify that is part of the default menu set is copied to the directory of your view in the menus directory before changes are made to it This protection of the built in palettes ensures that you can experiment with the palettes without corrupting the default view If you want to add a new object in a new row or column of a subpalette pop up in the space at the right edge or bottom of the subpalette You also can create new rows or columns by dragging objects to the area to the right or bottom of the palette Creating Subpalettes When you add a palette you can move it to a new location edit the subpalette icon or rename the palette using the Palettes Editor If you want to create a palette from scratch or hook in a palette that is not in user 1lib or vi lib you can
398. merical value Next the VI activates and reads the Max Value Cursor Then the VI calculates and displays information about the cursor selection on the front panel When you press the Confirm button the VI exits the loop and confirms the cursor positions See the examples in general graphs zoom 11b for an application of programmatically reading graph cursors National Instruments Corporation 20 15 G Programming Reference Manual Chapter Global and Local Variables This chapter describes how to define and use global and local variables You can use global variables to access a particular set of values easily Local variables serve a similar purpose within a single VI Global and local variables are advanced G concepts Be sure to study this chapter carefully before using them For examples of how to use global and local variables see general globals 11b and general locals 11b Global Variables A global variable is a built in G object You define a global variable by creating a special kind of VI with front panel controls that define the data type of the global variable There are two ways to create multiple global variables You can create several VIs each with one item or you can create one multiple global VI by defining multiple data types on the one global variable front panel The multiple global VI approach is more efficient because you can group related variables together You can create a global variable by sel
399. mine the causes of slow performance e Input Output files GPIB data acquisition networking e Screen Display large controls overlapping controls too many displays e Memory Management inefficient usage of arrays and strings inefficient data structures Other factors such as execution overhead and subVI call overhead can have an effect but these are usually minimal and not the most critical source of slow execution Input Output Input Output calls generally incur a lot of overhead They often take an order of magnitude more time than the time it takes to perform a computational operation For example a simple serial port read operation might have an associated overhead of several milliseconds This amount of overhead is true for any application that uses serial ports The reason for this overhead is that an I O call involves transferring information through several layers of an operating system The best method for addressing too much overhead is to minimize the number of I O calls you make Your performance improves if you can structure your application so that you transfer a lot of data with each call instead of making multiple I O calls using smaller amounts of data For example if you are creating a data acquisition NI DAQ VI you have a couple of options for reading data You can use a single point data transfer function such as the AI Sample Channel VI or you can use a multi point data transfer function such as the
400. n Text amp Pict Ring L 7 Rings are particularly useful for selecting mutually exclusive options such as trigger modes For example you might want users to be able to choose from continuous single and external triggering as shown in the following illustration A Honto ki hs Continuous Single External In the preceding example the ring labeled Trigger Mode has three mode descriptors one after another in the text display of the ring G arranges items in a circular list like a Rolodex with only one item visible at a time Each item has a numeric value which ranges from zero to n 1 where n is the number of items three in this example The value of the ring however can be any value in its numeric data range It displays the last item External above for any value greater than or equal to two and the first item Cont inuous above for any value less than or equal to zero National Instruments Corporation 13 7 G Programming Reference Manual Chapter 13 List and Ring Controls and Indicators Users can use this ring to choose an option from an easy to understand list without having to know what value that option represents The value associated with the selected option passes to the block diagram where for example you can use it to select a case from a Case Structure conditional code that carries out the selected option You can select an item in a ring control two ways You can use the incremen
401. n Glossary Central Processing Unit VI whose front panel block diagram or Icon Editor is the active window Controls and indicators whose parts can be replaced by graphics and indicators you supply Process of acquiring data typically from A D or digital input plug in boards Condition in a dataflow programming language in which a node cannot execute until it receives data from another node See also artificial data dependency Programming system consisting of executable nodes in which nodes execute only when they have received all required input data and produce output automatically when they have executed G is a dataflow system Generally to acquire data and simultaneously store it in a disk file G file I O functions can log data The arrangement and representation of data stored in memory Code that identifies data types used in data storage and representation File that stores data as a sequence of records of a single arbitrary data type that you specify when you create the file While all the records in a datalog file must be of a single type that type can be complex for instance you can specify that each record is a cluster containing a string a number and an array Online documentation for a G object See sink terminal An interactive screen with prompts in which you describe additional information needed to complete a command Size and structure attribute of an array G 5 G Programming Reference
402. n a wire selects a segment Double clicking on it selects a branch Triple clicking on it selects an entire wire Press the lt Delete gt key or lt Backspace gt key to remove the selected portion of wire This process is shown in the following illustration G Programming Reference Manual 17 6 National Instruments Corporation Chapter 17 Wiring the Block Diagram segment One click selects a segment Two clicks Three clicks select select a branch an entire wire To reposition a wire segment drag it to the new location with the Positioning tool You can reposition one or more segments by selecting and dragging them You also can move selected segments one pixel at a time by pressing the arrow keys on the keyboard Adjacent unselected segments stretch to accommodate the change You can select and drag National Instruments Corporation 17 7 G Programming Reference Manual Chapter 17 Wiring the Block Diagram multiple wire segments even discontinuous segments simultaneously as shown in the following illustration Sometimes repositioning a wired object results in an extra segment or oddly positioned wire segment as shown in the preceding example If you do not like the way the wire looks you can move it Use the lt Shift gt key to restrict the wire drag in horizontal or vertical direction The direction in which you initially move determines if the wire is limited to horizontal or vertical translation When you move
403. n gt key 1 Ifyou associate the lt Enter gt or the lt Return gt key with a control then no control on that front panel ever receives a carriage return Consequently all strings on the front panel are limited to a single line 2 When you tab from control to control buttons are treated specially If you tab to a button and press the lt Enter gt or lt Return gt key the button you tabbed to is toggled even if another control has the lt Enter gt or lt Return gt key as its key navigation setting You cannot assign the same key combination to more than one control in a given front panel G Programming Reference Manual 8 6 National Instruments Corporation Chapter 8 Introduction to Front Panel Objects When you select the Key Navigation option G displays the following dialog box Key Navigation x Key Assignment Current Assignments Nene J Modifiers EE E C Skip this control when tabbing Some keyboards might not have lt Home gt lt End gt lt Page Up gt lt Page Down gt or lt Clear gt keys Some keyboards do not have function keys or might only have You use the ring at the top left of this dialog box to select the key for this control You can define the key to be a single key or a key held in combination with a modifier key such as the lt Shift gt key In addition to the lt Shift gt key modifier you can choose the menu key which is the lt Alt gt Windows and HP UX
404. n oseane ein eh ed i a aa EE A 3 Byte nte gei n en succeed dh aopen reota EEEE orri O TE ra TEEI Eos Ene ti A 3 AMAY S ee err eis et a E E EE E ote ale Slain E EE E E aioe Bie A 3 SUITES ors ra ae r E E E E RET EE E EEE eons A 5 DEEE SEE ONE ATE oe EEE EEE EE E eee A 5 NEAT AE T EE E A E A AER TE AE EE E NA A 5 Type Descriptors enie n a a e a e E E EE oeteteces A 7 Data Typ s ernennen nnee rra er a E E E E E E teow A 8 ATT AY enee a cock uncs e O a e Seu E E capi Ea ERENS A 11 E AT S EA TREE EE A EEEE EE E ANE EN A 11 Flattened D L1 B ESIE ech E E E EE E E A OEE EE EES A 12 OOO a et a A 13 Strings Handles and P thserinnn conrei ei a ekoa A 13 ANT e D E EEEE EET A A E EA A 13 LEN EIS p aA EA E E E AE E E A 14 National Instruments Corporation xix G Programming Reference Manual Table of Contents Appendix B Common Questions about G Charts and Graphs ne eiee a cs cence ee ET EE SEA sh E E SEEE E EE TET E aS B 1 Error Messages and Crashes seeeeseeeeseeseeeseseersesrertssesreserresrerrerentsrestestseressererseeresreet B 4 Platform Issues and Compatibilities ssseesesseeessseeseseeetsrrstrsrsreerssresesrsserrssrerrsrenterenrrersee B 6 P a A E A A A O E a iets B 7 Miscellaneous sniene niri oter ser E EE ema eta ane aH B 9 Appendix C Customer Communication Glossary Index Tables Table 4 1 Table 4 2 Table 9 1 Table 9 2 Table 9 3 Table 9 4 Table 9 5 Table 9 6 Table 11 1 Table 16 1
405. n the alphanumeric keyboard enters a carriage return National Instruments Corporation 11 1 G Programming Reference Manual Chapter 11 String Controls and Indicators When the text reaches the right border of the display window the string wraps to the next line breaking on a natural separator such as a space or tab character ir Note When running a VI you use the lt Tab gt key to move to the next control When editing a VI pressing the lt Tab gt key changes tools To enter a tab character into a string select the V Codes option from the string pop up menu and type t To enter a linefeed into a string press the lt Enter gt Windows and HP UX or lt Return gt Macintosh and Sun key on the alphanumeric keyboard or select the Codes option from the string pop up menu and type n To enter a carriage return into a string select the Codes option from the string pop up menu and type r LabVIEW users should refer to Table 12 1 LabVIEW V Codes for a complete list of V codes For information on manipulating strings see the Online Reference Function and VI Reference String Functions topic Also see the examples in general strings 1llb String Control and Indicator Options Strings have special features that you can access through the string pop up menu shown in the following illustration Change to Indicator Find Terminal Show d Data Operations d Create Attribute Node Key Navigation R
406. n use Drag amp Drop to launch one or more VIs or VI libraries G Programming Reference Manual B 14 National Instruments Corporation Appendix B Common Questions about G UNIX LabVIEW responds to command line options to launch a particular VI when opened Therefore you can type labview usr home test vi or labview usr home test llb test vi to launch the Test VI depending on the correct path You can use a simple script to make a command that launches LabVIEW witha particular VI How do programmatically change the entries of an enumerated type You cannot programmatically change the type the strings of an enumerated data type just as you cannot programmatically change an integer control into a double or a string control into a path control The strings in an Enum are a part of its data type and thus can only be changed during edit time It is possible to read the strings of the Enum through an Attribute Node but you cannot write them using an Attribute Node If you need to programmatically change the text values in the Enum use a text ring control instead You can use the ring control to programmatically read and write the strings through the Strings attribute Because text rings are just numeric controls they do not associate the strings with their data type How do hide the menu bars of a VI All VI attributes including whether the menu bar and the toolbar are displayed are set through the dialog box in VI
407. n which you intend to use the file You can use any of the following compilers The Windows compilers also include tools for creating help documents e Windows RoboHelp from Blue Sky Software 1 800 677 4946 for international customers 619 459 6365 e Windows Doc To Help from WexTech Systems Inc 1 800 939 8324 e Macintosh QuickView from Altura Software 408 655 8005 e UNIX HyperHelp from Bristol Technologies 203 438 6969 When you have created and compiled your help files you can link them directly to a VI Pop up on the VI connector pane of the VI for which you want to link a file and select VI Setup Documentation Select the Help Tag box and type the topic you would like to link to in the help file Choose the help file by clicking on the Browse button The path of the file appears in the Help Path box G Programming Reference Manual 1 10 National Instruments Corporation Chapter Building Vis This chapter discusses basic features you need to be familiar with so you can build or use VIs including information about palettes and menus It also discusses basic tasks you need to learn such as how to create objects change tools and how to open run and save VIs G Environment You use palettes and menus to build VIs You can choose objects from palettes to position on the front panel of the block diagram These objects can be moved or modified by the use of menus Note If you are a Bridge VIEW
408. nal Instruments Corporation Chapter 25 Managing Your Applications Printing History Information When you print a VI you can include the history and revision number by selecting Complete Documentation from the Print Documentation dialog box If you want to change the format of the printout to include only the history information you can use the Custom Print Settings button to indicate exactly what you want to print Additionally you can export the history information to a file by selecting Save Text Info from the Print Documentation dialog box Setting Related VI Setup amp Preference Dialog Box Options The VI Setup and the Preferences dialog boxes both have options you can use to indicate how VI history should behave You can use the VI Setup options to indicate for a given VI if and when history information is automatically recorded See the Documentation Options section of Chapter 6 Setting up VIs and SubVIs for information on these settings You can use the Preferences dialog box options to indicate what the default history settings are for new VIs You can also use this dialog box to indicate a user name entered in history information See the History Preferences section of Chapter 7 Customizing Your G Environment for information on these settings National Instruments Corporation 25 9 G Programming Reference Manual Chapter Performance Issues This chapter is divided into three sections The first section discuss
409. name for the VI G does not overwrite or delete the disk version of the original VI When you select the Save A Copy As option G saves a copy of the VI in memory to disk with the name you enter This does not affect the name of the VI in memory Save with Options brings up a dialog box in which you can choose to save an entire VI hierarchy to disk optionally saving VIs without their block diagrams This option is useful when you are distributing VIs or making backup copies See Chapter 25 Managing Your Applications for instructions on how to use this option WV Caution You cannot edit a VI after you save it without a block diagram Always make a copy of the original VI You can use the File Revert option to return to the last saved version of the VI you are working on A dialog box appears to confirm whether to discard all changes made to the VI VIs that have been modified since they were last saved are marked with an asterisk in their titlebars and in the list of open VIs displayed in the Windows menu When you save a VI the asterisk disappears until you make a new change See Chapter 25 Managing Your Applications for information on saving backup copies G Programming Reference Manual 2 28 National Instruments Corporation Chapter 2 Building Vis Caution Do not save your VIs in the vi lib directory National Instruments wy updates this directory as needed during new version releases of G Placing VIs in vi lib r
410. natch Cif to search Tose offset 1 H a start location ic Developing Efficient Data Structures One of the points made in the previous section is that hierarchical data structures such as arrays of clusters containing large arrays or strings or clusters containing large arrays or strings cannot be manipulated efficiently This section explains why this is so and describes strategies for choosing more efficient data types G Programming Reference Manual 26 28 National Instruments Corporation Chapter 26 Performance Issues The issue with complicated data structures is that it is difficult to access and change elements within a data structure without causing copies of the elements you are accessing to be generated If these elements are large as in the case where the element itself is an array or string these extra copies use more memory and the time that it takes to copy the memory You can generally manipulate scalar data types very efficiently Likewise you can efficiently manipulate small strings and arrays where the element is a scalar In the case of an array of scalars the following code shows what you would have to do to increment a value in an array This is quite efficient because no extra copies of the overall array need to be generated Also the element produced by the Index Array function is a scalar which can be created and manipulated efficiently The same is true of an arra
411. nce Manual Chapter Setting up Vis and SubVis This chapter discusses how you can use the VI Setup and SubVI Node Setup dialog boxes to customize the behavior of a subVI You can use these dialog boxes to create subVIs that show their panels when they are called and to enable and disable features of a panel such as the scrollbars the toolbar and the window resizing capability Creating Pop Up Panels A single front panel is sometimes too restrictive if you need to present numerous options or displays The best solution to this problem is to organize your VIs so that high level options are presented in your topmost VI and related options are presented by subVIs When G calls a subVI it ordinarily runs without opening its front panel You can use the VI Setup or SubVI Node Setup dialog boxes to make a subVI open its front panel when the subVI is called and close the front panel when the subVI completes execution You access the VI Setup dialog box by popping up on the VI icon in the top right of a front panel and selecting VI Setup as shown in the following illustration You must be in edit mode UI Setup Edit Icon Show Connector Paiiq ure pisie Gb Bearees Pip Horironted Pilg Perii Hianariead f Hi Porcinnis iiiqgnpyerecad Finds Peas yepiyeaii hig Cerra tinny Es a National Instruments Corporation 6 1 G Programming Reference Manual Chapter 6 Setting up Vis and SubVIs This dialog box contains
412. nce Manual Chapter 17 Wiring the Block Diagram The following figure shows a list of some possible wire errors They cannot all occur simultaneously for a single wire Signal type conflict has multiple sources has no Source dimension conflict element conflict has loose ends Dis a member of a cycle has file refnum conflict Dunit conflict has loops For information on wiring Structures see the Structure Wiring Problems section in Chapter 18 Structures in this manual Wire Type Dimension Unit or Element Conflict A type mismatch occurs when you wire two objects of different data types together such as a numeric and a Boolean as shown in the following illustration A file refnum conflict results when you wire refnums for two datalog files of different record types The dimension conflict and element conflict errors occur in similar situations when you wire two arrays together whose elements match but whose dimensions do not and when you wire two clusters whose elements have type differences respectively The unit conflict occurs when you wire together two objects that do not have commensurable units These problems typically arise when you inadvertently connect a wire to the wrong terminal of a function or subVI Select and remove the wire and rewire to the correct terminal You can use the Help window to avoid this type of error In other situations you might have to change the type of one of t
413. nce Manual for more information Structures which supplement the G dataflow programming model to control execution order are discussed briefly in the Structures section of this chapter for in depth information see Chapter 18 Structures Formula Nodes which supplement G functions by using formulas on the block diagram are discussed in Chapter 19 Formula Nodes Attribute Nodes which change control attributes programmatically are discussed in Chapter 20 Attribute Nodes Functions Functions are elementary nodes built into G They perform elementary operations like adding numbers file I O and string formatting G functions do not have front panels or block diagrams When compiled they generate inline machine code See Online Reference Function and VI Reference for detailed descriptions of individual functions You select functions from the Functions palette as shown in the following illustration G Programming Reference Manual 16 8 National Instruments Corporation Chapter 16 Introduction to the Block Diagram When you select a function its icon appears on the block diagram To display its label pop up on the icon and select Show Label You can change the label if you want by highlighting the text with the Labeling tool and typing over it You can use the label of the function to annotate its purpose in the block diagram You can use the Help window to see how to wire the function or you can select Show Termin
414. nd Ring Controls and Indicators Keyboard Mode You use Keyboard Mode from the pop up menu shown in the illustration that follows to indicate how the listbox should treat upper and lower case characters when you select options by typing their initial letters Change to Indicator Find gt Show gt Data Operations gt Create gt Key Navigation Replace gt Selection Mode gt ae System Default Case Sensitive Disable ltem Case Insensitive tem Symbol Keyboard Mode If you select Case Sensitive an item is selected only if the uppercase and lowercase letters of what the user types exactly match the item If you select Case Insensitive case is ignored If you select System Default the default setting for a listbox the listbox behaves the same way that other listboxes do for a given platform Specifically in Windows and on the Macintosh the listbox is case insensitive In UNIX the listbox is case sensitive Creating a Grayed Out Dividing Line If you use a value of 1 for the symbol of an option the listbox draws a grayed out dividing line instead of drawing the name of the option G Programming Reference Manual 13 6 National Instruments Corporation Chapter 13 List and Ring Controls and Indicators Ring Controls Rings are special numeric objects that associate unsigned 16 bit integers with strings pictures or both The different styles of rings are shown in the following illustratio
415. nd UNIX right clicking on the object with the mouse button e Macintosh lt command gt clicking on the mouse button See Chapter 2 Building VIs and the Front Panel Objects section of this manual Chapters 8 through 15 for information about how to build a front panel Block Diagram The Diagram window holds the block diagram of the VI which is the graphical source code of a VI You construct the block diagram by wiring together objects that send or receive data perform specific functions and control the flow of execution The following simple VI computes the sum of and difference between two numbers The diagram shows several primary block diagram program objects nodes terminals and wires Add amp 5 oj ee j ij Spt Ap Add Subtract vi Diagram 44 Spt Application Font 2 Ea 0 00 0 0 El When you place a control or indicator on the front panel a corresponding terminal appears on the block diagram You cannot delete a terminal that belongs to a control or indicator The terminal disappears only when you delete its control or indicator on the front panel The Add and Subtract function icons also have terminals Think of terminals as entry and exit ports Data that you enter into the controls a and b exits the front panel through the control terminals on the block G Programmi
416. nd the plot color for the active plot Active Plot is an integer corresponding to the plot you want and Plot Color is an integer representing a color You can access the Plot Color by selecting Plot Info Plot Color from the attribute list This Attribute Node changes the plot color of the plot specified by the Active Plot attribute In the following example the color of the random G Programming Reference Manual 20 10 National Instruments Corporation Chapter 20 Attribute Nodes number plot changes color when the values go above a limit set by the user Notice that the active plot is specified before the plot color is changed Setting the Strings of a Boolean Attribute rotrin qs 4 This Boolean attribute sets or reads the labels on a Boolean control The input is an array of four strings that correspond to the False True True Tracking and False Tracking states e True and False On and Off states of the Boolean e True and False Tracking Temporary transition levels between the Boolean states True Tracking is the transition when the Boolean is changed from True to False False Tracking is the transition from False to True when the Boolean attribute is changed The tracking applies only to Booleans with Switched When Released and Latch When Released mechanical action These mechanical actions have a transitional state until you release the mouse The text strings True Tracking and False Tracking are dis
417. ndicators graphs and charts and wiring the block diagram Organization of This Manual This manual covers four subject areas Chapters 1 through 7 introduce basic G concepts Chapters 8 through 15 explain how to use front panel objects Chapters 16 through 21 explain block diagram programming objects and techniques and Chapters 22 through 27 cover advanced G topics Basic G Concepts National Instruments Corporation Chapter 1 Introduction to G Programming discusses the unique G approach to programming It also explains how to start using G to develop programs Chapter 2 Building VIs discusses basic features you need to be familiar with so you can build or use VIs including information about palettes and menus It also discusses basic tasks you need to learn such as how to create objects change tools and how to open run and save VIs Chapter 3 Building SubVIs discusses the concept of hierarchical design in your G applications and explains two methods of creating subVIs The chapter also describes two utilities the Hierarchy window which displays the hierarchy of your VIs and the Find utility which finds occurrences of subVIs as well as other objects or strings of text that you indicate Chapter 4 Executing and Debugging VIs and SubVIs discusses how to operate and debug VIs and explains how to set up VIs and subVIs for special execution modes Chapter 5 Printing VIs discusses printing issues in G xxi G
418. ndow are added for new VIs The second group of options in the History Preferences dialog box concerns how you log in to G which in turn determines the name G inserts in the headers to comments entered in the VI History window Options concerning History window entries can be specified for individual VIs through the VI Setup Documentation dialog box See Documentation Options in Chapter 6 Setting up VIs and SubVIs for information about accessing the options The options in this dialog box are as follows Add an entry every time VI is saved Directs G to add an entry to the VI history every time you save the VI If you have not entered a comment in the Comment box of the History window only a header is added to the history The header contains the revision number if that option further down in this dialog box is checked the date and time and the name of the VI Prompt for comment when VI is saved Directs G to bring up the History window when you save so that you can enter a comment This is useful if you prefer to comment on your changes when you finish G Programming Reference Manual 7 18 National Instruments Corporation Chapter 7 Customizing Your G Environment making them instead of as you are editing If you do not set this option you will not have a chance to change the history of the VI after you select Save until the save is finished Prompt for comment when VI is closed Similar to the previous option except t
419. ne Data flow is the principle that governs G program execution Stated simply a node executes only when all data inputs have arrived the node supplies data to all of its output terminals when it finishes executing the data passes immediately from source to sink terminals Dataflow programming contrasts with the control flow method of executing a conventional program in which instructions are executed in the sequence in which they are written Control flow execution is instruction driven Dataflow execution is data driven or data dependent You can switch from the front panel to the block diagram by selecting Windows Show Panel from the menu See the Block Diagram Programming section of this manual Chapters 16 through 21 for in depth information about using block diagram objects to build a program National Instruments Corporation 1 5 G Programming Reference Manual Chapter 1 Introduction to G Programming Icon and Connector When an icon of a VI is placed on the diagram of another VI it becomes a subVI the G equivalent of a subroutine The controls and indicators of a subVI receive data from and return data to the diagram of the calling VI The connector is a set of terminals that correspond to the subVI controls and indicators The icon is either the pictorial representation of the purpose of the VI or a textual description of the VI or its terminals The connector is much like the parameter list of a function call th
420. ne an existing node click on that node and drag it with the Positioning tool while holding down the lt Ct r1 gt Windows lt opt ion gt Macintosh lt meta gt Sun or lt Alt gt HP UX key However you cannot copy and paste an Attribute Node using the Edit menu commands Each node can have both read and write attribute terminals G Programming Reference Manual 20 4 National Instruments Corporation Chapter 20 Attribute Nodes es es E Wisible Wisible Precision i Precision The attributes for a cluster and for a numeric control inside the cluster are shown in the following illustration Disible Disabled Key Focus lt Visible Disabled Key Focus Format amp Precision Text Colors Some controls such as the graph have a large number of attributes you can read or set Some of these attributes are grouped into categories and listed in submenus such as the Format amp Precision category for a numeric control You can choose to set all of the attributes at once by selecting the All Elements option of the submenu You also can set one or more of the elements individually by selecting the specific National Instruments Corporation 20 5 G Programming Reference Manual Chapter 20 Attribute Nodes attribute s The Format amp Precision option on a numeric control is shown in the following illustration as an example Disible Disabled Key Focus Format Precision After you create an Attri
421. ne is visible G selects the corresponding assigned object Creating SubVls from VI Selections You can convert a portion of a VI into a subVI that can be called from another VI You select a section of a VI select Edit SubVI From Selection and the section becomes a subVI Controls and indicators are created automatically for the new subVI the subVI is wired automatically to the existing wires and an icon of the subVI replaces the selected section of the block diagram in your original VI G Programming Reference Manual 3 10 National Instruments Corporation Chapter 3 Building SubVis Creating a subVI from a selection is the same as removing the selected objects and replacing them with a subVI except for the following behaviors e None of the front panel terminals included in the selection are removed from the caller VI Instead the front panel terminals are retained on the caller VI and are wired to the subVI e All attributes included in the selection are retained on the caller VI and are wired to the subVI The selected attributes are replaced by front panel terminals in the subVI which act as channels for transferring the value of an attribute in or out of the subVI e When a selection includes a local variable it is replaced by a front panel terminal in the subVI The local variable is retained on the caller VI and is wired to the subVI When more than one instance of the same local variable is selected the first instanc
422. ng Reference Manual 1 4 National Instruments Corporation Chapter 1 Introduction to G Programming diagram The data then enters the Add and Subtract functions When the Add and Subtract functions complete their internal calculations they produce new data values at their exit terminals The data flows to the indicator terminals and reenters the front panel where it is displayed The data exits from a source terminal and enters a destination or sink terminal Nodes are program execution elements They are analogous to statements operators functions and subroutines in conventional programming languages The Add and Subtract functions are one type of node G has an extensive library of functions for math comparison conversion I O and more Another type of node is a structure Structures are graphical representations of the loops and case statements of traditional programming languages by repeating blocks of code or executing them conditionally G also has special nodes for linking to external text based code and for evaluating text based formulas Wires are the data paths between source and sink terminals You cannot wire a source terminal to another source nor can you wire a sink terminal to another sink However you can wire one source to several sinks Each wire has a different style or color depending on the value that flows through the wire The previous example shows the wire style for a numeric scalar value a thin solid li
423. ng conditions e The front panel is in memory this can occur for any of the following reasons The front panel is open The VI has been changed but has not been saved all components of the VI remain in memory until the VI has been saved The panel uses data printing The diagram uses Attribute Nodes National Instruments Corporation 26 19 G Programming Reference Manual Chapter 26 Performance Issues The VI uses local variables The panel uses data logging A control uses suspend data range checking A few of these reasons are not intuitive and need further explanation One reason concerns attributes such as chart history For an Attribute Node to be able to read the chart history in subVIs that are not open the control or indicator needs to go through the motions of displaying the data that is passed to controls and indicators Because there are numerous other attributes like this the execution system keeps subVI panels in memory if the subVI uses Attribute Nodes If a front panel uses front panel datalogging or data printing then controls and indicators maintain copies of their data In addition panels are kept in memory for data printing so that the panel can be printed out If a VI uses Suspend data range checking data is copied to and from all front panel controls and indicators The front panel values are retained so that the front panel can be displayed if any data goes out of range Do not
424. ng list of options 13 2 data types 13 3 grayed out dividing line 13 6 Multiple Selection 13 2 pop up menu options 13 3 to 13 6 illustration 13 3 Keyboard Mode 13 5 Selection Mode 13 4 to 13 5 Show 13 4 purpose and use 13 1 to 13 2 selecting listbox items 13 2 to 13 3 Single Selection 13 1 symbols for listbox items 13 4 LLBs See VI libraries LLBs Local Variable palette 21 4 local variables 21 3 to 21 5 avoiding cycles in subVIs Attribute Nodes in Case Structures 3 13 locals in Case Structures 3 13 locals within loops 3 13 creating 21 4 Find pop up menu 3 29 G Programming Reference Manual inability to reuse data memory 26 20 to 26 21 memory usage 26 20 to 26 21 multiple local variables 21 5 Lock Help command 1 7 Lock to Plot option 15 36 Log at Completion option 4 6 Log option 4 6 logging data See data logging on front panel logging in automatic login using system user name 7 20 showing login prompt at startup time 7 19 long integer numeric data storage format A 3 loops See For Loops While Loops Loose Fit option 15 17 Make Current Value Default option 14 12 14 21 Make This Case option 18 21 managing applications See applications managing manual See documentation National Instruments Mapping Mode option 15 15 Mapping option 9 15 marker spacing adding or deleting markers 15 14 non uniform distribution 15 14 Marker Spacing option graph indicators 15 13 to 15 14 sli
425. ng option is described in G Programming Reference Manual 6 2 National Instruments Corporation Chapter 6 Setting up Vis and SubVIs the Debugging Features section of Chapter 4 Executing and Debugging VIs and SubVIs The Reentrant Execution and Priority options are fairly advanced features that affect the way a VI executes You need them only in special applications These options are discussed in the Reentrant Execution and VI Setup Priority Setting sections respectively of Chapter 24 Understanding the G Execution System You can use the remaining options to set your VI to print when executed and customize the way it looks when printed in this way Programmatic printing is discussed in detail in the Programmatic Printing section of Chapter 5 Printing VIs Documentation Options The dialog box in VI Setup Documentation shown in the following illustration presents you with options concerning entries made to the History window which displays the development history of the VI For information on the History window see the VI History Window section in Chapter 25 Managing Your Applications Ul Setup 4dd an entry every time this Vl is saved Help Tag Prompt for comment when this lis closed Prompt for comment when this YI is saved Help Path Record comments generated by LabY lew Use History Defaults Cin Preference Dialog a Caan To use any of the first four options in t
426. ng the left mouse button pressed This ergonomic feature relieves strain on the hand Note Changes to options in the Miscellaneous Preferences dialog box take effect immediately How Preferences Are Stored Usually you do not have to edit preference information manually or know its exact format because the Preferences dialog box takes care of it for you Preferences are stored differently on each platform as described in the following paragraphs Windows Preference information is stored in a LabVIEW INI file in your LabVIEW directory if you are a LabVIEW user The format for this file is similar to other INI files such as the WIN INT file It begins with a section marker LabVIEW If you are a Bridge VIEW user you can find preference information stored in a BridgeVIEW INI file in your BridgeVIEW directory The format for this file is similar to other INI files It begins with a section marker BridgeVIEWw This is followed by variable labels and their values such as offscreenUpdates True If a configuration value is not defined in LABVIEW INI LabVIEW checks to see if there is a LabVIEW section of your WIN INT file and if so checks for the configuration value in that file Note The references to WIN IN1 files applies only to Windows 3 1 If you are a BridgeVIEW user this information does not apply to the Windows platform you are using You also can specify a preference file on the command line when y
427. ngs and maximize symmetry which is useful after successive operations on hierarchy nodes If a focus node exists the window is scrolled to make that node visible If no focus node exists the window is scrolled to make the first root showing subVIs visible Vertical Layout Arranges the nodes from top to bottom with the calling VIs above their subVIs a gt Horizontal Layout Arranges the nodes from left to right with the calling VIs to the left of their subVIs Include VI Lib Toggles the Hierarchy window to Eli include or exclude VIs in vi lib Include Globals Toggles the Hierarchy window to include or exclude globals e 48 Include Type Definitions Toggles the Hierarchy window to siS include or exclude type definitions National Instruments Corporation 3 19 G Programming Reference Manual Chapter 3 Building SubVis Hierarchy Node Pop Up Menu If you pop up on a node subVI global variable or type definition displayed in the Hierarchy window a menu appears with options for controlling the display or carrying out commands related to the selected node Highlight Connections Show Immediate Sublls Show Ul Hierarchy Show All Subs Show All Callers Edit Icon UT Setup Get Info Open Front Panel Print Documentation The options are described as follows G Programming Reference Manual Highlight Connections Makes the selected node the focus node and highlights in red the ed
428. nication Applications of the LabVIEW Communications VI National Instruments Corporation 23 1 G Programming Reference Manual Chapter 23 Calling Code from Other Languages Reference Manual for details of different methods for using Apple Event VIs in G to launch and control other applications Using the Call Library Function You can call most standard shared libraries in Windows these are Dynamic Link Libraries or DLLs on the Macintosh they are Code Fragments and on UNIX they are Shared Libraries using the Call Library Function node The Call Library Function node includes a large number of data types and calling conventions You can use it to call functions from most standard and custom made libraries The Call Library Function node is most appropriate when you have existing code that you want to call or if you are familiar with the process of creating a DLL in Windows Code Fragments on the Macintosh or Shared Libraries on UNIX Because a library uses a format that is standard among several development environments you should be able to use almost any development environment to create a library that G can call Check the documentation for the compiler you are using to see if it can be used to create standard shared libraries See the section Call Library Function later in this chapter for a detailed description of this node Using Code Interface Nodes For applications in which you need the highest performance or you want to
429. nition 16 8 displaying labels 16 9 National Instruments Corporation expandable functions 16 10 overview 16 8 Functions option Select Objects menu 3 25 Functions palette Advanced palette 23 3 Communication option 5 1 customizing See Controls and Functions palettes customizing illustration 16 9 pop up palette 2 3 selecting objects 2 1 to 2 3 temporary copy 2 3 G G environment 2 1 to 2 6 See also G environment customizing dataflow programming 1 5 help information 1 7 to 1 9 attribute node help 1 9 block diagram help 1 7 to 1 9 creating your own help files 1 9 to 1 10 front panel help 1 7 online reference 1 9 menus 2 6 overview 1 1 pop up menus 2 6 questions charts and graphs B 1 to B 4 error messages and crashes B 4 to B 5 miscellaneous questions B 9 to B 16 platform issues and compatibilities B 6 printing B 7 to B 9 switching to Basic G palette from BridgeVIEW note 2 1 Tools palette 2 4 to 2 5 National Instruments Corporation Index G environment customizing controls and functions palettes 7 25 to 7 29 adding VIs and controls to user 1ib and instr lib 7 25 creating subpalettes 7 27 to 7 29 installing and changing views 7 26 moving subpalettes 7 29 Palettes editor 7 26 to 7 27 views 7 29 Preferences Dialog Box options 7 1 to 7 24 block diagram preferences 7 11 to 7 12 color preferences 7 13 to 7 14 debugging preferences 7 12 to 7 13 font preferences 7
430. not call variable argument functions Shared libraries on the Macintosh operate differently than on other platforms A file might contain more than one code fragment each of which has a name FB 2 The Call Library Function shown at left is available from Functions Advanced If you double click on the Call Library Function or select Configure from its node pop up menu G displays a dialog box you can use to specify from the library function parameters and return value for the node as well as calling conventions in Windows When you click the OK button the node automatically adds the correct number of terminals and sets the terminals to the correct data types The return value for the function returns to the right terminal of the top pair of terminals of the node If there is no return value this pair of terminals is unused Each additional pair of terminals corresponds to a parameter in the functions parameter list You pass a value to the function by wiring to the left terminal of a terminal pair You read the value of a parameter after the function call by wiring from the right terminal of a terminal pair National Instruments Corporation 23 3 G Programming Reference Manual Chapter 23 Calling Code from Other Languages The Call Library Function dialog box is shown in the following illustration Call Library Function x Library Name or Path Function Name ffuncName Calling Conventions Default stdcal
431. nput terminals and front panel indicator terminals also are called destination or sink terminals because they receive the data National Instruments Corporation 16 1 G Programming Reference Manual Chapter 16 G Programming Reference Manual 1 Introduction to the Block Diagram Control and Indicator Terminals You enter values into front panel controls and when a VI executes the control terminals pass these values to the block diagram When the VI finishes executing the output data passes from the block diagram to the front panel indicators through the indicator terminals The symbols for some of the G control and indicator terminals are shown in Table 16 1 G Control and Indicator Terminal Symbols Each symbol encloses a picture that suggests the data type of the control or indicator and in the case of numerics the representation as well Control terminals have a thicker border than indicator terminals Because a terminal belongs to its corresponding control or indicator you cannot delete a terminal if you want to delete a control do it from the front panel An array terminal encloses one of the data types shown in square brackets and takes on the color of the data type of the array Table 16 1 G Control and Indicator Terminal Symbols Control Indicator Description Color EXT Extended precision Cenk floating point 5 pet DEL Double precision Orange me floating point j euL
432. ns along with suggestions for the best data structures in each case Case Study 1 Avoiding Complicated Data Types Consider an application in which you want to record the results of several tests In the results you want a string describing the test and an array of the test results One data type you might consider using to store this information is shown in the following illustration To change an element in the array you have to index an element of the overall array Now for that cluster you have to unbundle the elements to reach the array You then replace an element of the array and store the resulting array in the cluster Finally you store the resulting cluster G Programming Reference Manual 26 30 National Instruments Corporation Chapter 26 Performance Issues into the original array An example of this is shown in the following illustration test to update Each level of unbundling indexing might result in a copy of that data being generated Notice that a copy is not necessarily generated The rules for when a copy is made are complex and are discussed in LabVIEW Technical Note 020 Minimizing the Number of Data Buffers Copying data is costly in terms of both time and memory The solution is to try to make the data structures as flat as possible For example in this case study you could break the data structure into two arrays The first array would be the array of strings The second array would be a 2D array
433. nstants inside a Case Structure The small T in the Color palette represents the transparent color G Programming Reference Manual 9 24 National Instruments Corporation Color Ramp Chapter 9 Numeric Controls and Indicators The color ramp displays a color corresponding to a specified value You can configure a color scale which consists of at least two arbitrary markers each consisting of a level and the display color corresponding to that level As the input value changes the color displayed changes to the color corresponding to that value An example is shown in the following illustration overflow color color display area underflow color digital display You create these pairs using the arbitrary markers of the color scale Each arbitrary marker specifies a level and has a color associated with it When the color ramp first appears on the front panel it is set to have three levels Level 0 is set to the value 0 and the color black Level 1 is set to the value 50 and the color blue Level 2 is set to the value 100 and the color white You can add levels change the values and set the colors as you choose Use the Interpolate Colors option of the color ramp pop up menu to select a color if the control interpolates colors to display shades of color for values between the indicated levels or changes to a specific color only when the input value reaches a level specified in the color array If Interpolate Colors is off
434. nstrument Special file that contains a collection of related VIs for a specific use Program in LabVIEW or BridgeVIEW so called because it models the appearance and function of a physical instrument G 13 G Programming Reference Manual Glossary W While Loop Loop structure that repeats a section of code until a condition is met Comparable to a Do loop or a Repeat Until loop in conventional programming languages wire Data path between nodes Wiring tool Tool used to define data paths between source and sink terminals G Programming Reference Manual G 14 National Instruments Corporation A absolute time and date formatting digital displays 9 10 to 9 11 graph indicators 15 16 to 15 17 Active Plot Attribute 20 10 to 20 11 Add a Parameter After option 23 5 Add a Parameter Before option 23 5 Add an entry every time this VI is saved option 6 4 Add Case After option 13 11 18 19 Add Case Before option 18 19 Add command 16 10 to 16 11 Add Dimension option 14 7 Add Element Gap option 14 14 Add Element option 18 11 Add Input option 19 3 Add Item After option enumerated type controls 13 11 ring pop up 13 8 text display pop up 9 19 Add Item Before option enumerated type controls 13 11 ring pop up 13 8 text display pop up 9 19 Add Marker option 9 17 Add Needle option 9 22 Add Output option 19 3 Add Sequence Local option 18 17 Add Shift Register option 18 10 Add Slider option 9 20 Advanced palett
435. nteni ccs cesesessecsesseceeceseeeeceseseeceeceeseneseeseaeesaecaessaeras 25 5 VI History WIndows eoep Sey cerbessessagth ettennfevestieae des tere eerie hes G 25 5 Revision NUMbETS 0 cece er eee rae ae are a ES eao 25 7 Resetting History Information esesessseessseeersersreesreeresesresrsserrrsreresre 25 8 Printing History Information ssesessseeseeeeeessreesreerrsrsserrssreresresrsreereees 25 9 Setting Related VI Setup amp Preference Dialog Box Options 25 9 National Instruments Corporation xvii G Programming Reference Manual Table of Contents Chapter 26 Performance Issues Performance Profiling neis oeri aen E E E aee iE EE S OEE EE E EEE Es 26 1 Viewing the Results vsi cccassccssces ioeo aeriene oE eo a a lecnients secevebtetandes 26 3 Timing Information 55 cssse sssecsbescpecesceescssqesssevesesete ripo ni EEES eissii 26 4 Memory Information seseseesessseesessssesresreresreersreererreresreresrsseresreersrene 26 5 Speeding Up Your Viscsccncssehscesessssskstssusessavhsgesasetadie eb esoetecgepssvebeatin EE EES EE EE EST 26 6 Input Outputise 0 2 E Kiera wa a Seed ee Ra ek es Neca 26 6 Screen Display E EE ET 26 7 OMSL ASSUMES esos enere a ahs E e eae E EEEE EEE O aa 26 8 Parallel Diagram Seiri rrenari a aie ei e i 26 8 SUDVI Overhead ioen ore oeeie E OEE EEE EEE K ERs aee STE 26 9 Unnecessary Computation in Loops ssssessesessssssrssrsrrersreersreererreseerese 26 9 Memory Usage o e san
436. ntrols and Indicators for more information You can move a cursor on a graph or chart by dragging it with the Operating tool or by using the cursor movement control Clicking the arrows on the cursor movement control causes all cursors selected to move in the specified direction You select cursors either by moving them on the graph with the Operating tool or by clicking on the select button for a particular cursor In the following example the top two cursors can be moved vertically downwards 5 86 4 00 00 Clicking on the cursor display control with the Operating tool displays cursor display a pop up menu that you can use to control the look of the cursor and the control visibility of the cursor name on the plot This pop up menu is shown in the following illustration Cross Hair Point Style Color lisible Name Bring into View Goto Cursor From this menu you can select the style of the cross hairs The cross hairs can consist of a vertical and or horizontal line extending to infinity a smaller vertical and or horizontal line centered about the cursor location or no cross hairs as shown in the following illustration National Instruments Corporation 15 33 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators Point tyle Color lisible Name Bring into View Goto Cursor You also can choose the style of point to use for marking the cursor location and the color for the cursor a
437. ntrols and Functions palette objects on the front panel and block diagram Positioning tool Positions resizes and selects objects Labeling tool Edits text and creates free labels Wiring tool Wires objects together in the block diagram Object Pop up Menu tool Pops up on the menu of an object Scroll tool Scrolls through the window without using the scroll bars Breakpoint tool Sets breakpoints on VIs functions loops sequences and cases Probe tool Creates probes on wires Color Copy tool Copies colors for pasting with the Color tool Color tool Sets foreground and background colors Hua e is Ww ie ele e Change from one tool to another by doing any of the following while in edit mode e Click on the tool you want in the Tools palette e Use the lt Tab gt key to move through the most commonly used tools in sequence e Press the spacebar to toggle between the Operating tool and the Positioning tool when the front panel is active and between the Wiring tool and the Positioning tool when the block diagram is active National Instruments Corporation 2 5 G Programming Reference Manual Chapter 2 Building Vis Menus in G G uses menus extensively The menu bar at the top of a VI window or at the top of the Macintosh screen contains several pull down menus You can access pull down menus from a menu bar by clicking on a menu bar item The pull down menus are usually general in nature and contain
438. numbers Each number in the array represents a specific color The indices of an element in the two dimensional array set the plot location for this color G Programming Reference Manual 15 36 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators The following illustration shows the concept of the intensity chart operation Input Array Color Map Definition Column y Array Element 1 2 You can define the colors for the intensity chart interactively by using the color scale or you can define them programmatically through the chart Attribute Node The Color Mapping section later in this chapter explains the procedure for assigning a color to a number The array indices correspond to the lower left vertex of the block of color The block has a unit area as defined by the array indices The intensity chart can display up to 256 discrete colors After a block of data has been plotted the origin of the Cartesian plane is shifted to the right of the last data block When new data is sent to the National Instruments Corporation 15 37 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators intensity chart the new data appears to the right of the old data as shown in the following illustration New Input Array Column y 1 2 0 Resulting Plot 1 2 3 4 5 0 1 2 When the chart display is full the oldest data scrolls off the left side of the chart
439. nuous g lt digital display hd Enumeration Block diagram One advantage of enumerated types over ring controls is that if you use an enumerated type on the connector pane of a subVI then popping up to create a constant control or indicator will create an enumeration with the proper strings You enter items into an enumerated type the same way you enter items into aring using Add Item After or Add Item Before Or you can use the Labeling tool Press lt Shift Enter gt Windows and HP UX or lt Shift Return gt Macintosh and Sun to enter a new item Click on any area outside the enumerated type when you have finished entering items If an enumerated type is wired to a Case Structure the Case Structure must have one frame for each item in the enumerated type Pop up on the Case Structure and select Add Case After if you need more frames Like a ring the value of an enumerated type is the index of its current items You can pop up and select Show Digital Display All arithmetic operations except Add One and Subtract One treat the enumerated type the same as an unsigned numeric Add One increments the last enumeration to the first and Subtract One decrements the first enumeration to the last National Instruments Corporation 13 11 G Programming Reference Manual Chapter 13 List and Ring Controls and Indicators If you connect a numeric value to an enumerated type indicator G converts the number to the clo
440. o drivers select VGA from the list of video drivers in Windows Setup LabVIEW and Bridge VIEW use the standard Windows API for its graphical calls however we have found that many video drivers do not fully conform to this standard If the crashes do not occur with the standard VGA driver then itis a good idea to see an update to your video driver You should be able to obtain the latest release of the video driver software from both the manufacturer of your PC and the manufacturer of the video card Several customers have reported success after updating their drivers particularly when using the Mach32 shipped with ATI boards and Gateway machines or Cirrus Logic video drivers If the situation is not resolved by updating the video driver contact National Instruments Windows What should I do if I receive a memory parity error followed by a General Protection Fault Memory parity errors are the result of bad memory in your machine This memory might be virtual memory indicating a problem on your hard disk or physical memory indicating a bad SIMM To check for problems with your hard disk use a standard disk utility package such as Norton Utilities To check for problems with physical RAM you need to physically rotate the SIMMs in your machine rebooting the PC after each rotation When the bad SIMM is placed in the lowest bank of memory the machine will not boot at all It is a good idea to replace the SIMM National Instrumen
441. o er e a a Be A A a eA 3 26 Search String Options ssis seiiet sesoses isisisi isese ss 3 26 Text Search Options essiri sesiis iseken eisso 3 27 Narrowing the Search Scope e seseeeesseresrssssesssserreseeersrrerereeseressenees 3 27 Search Results Window 000 cece ceeeeesceseeeeceseeeeeceesaecseeaecnecsseeseeesees 3 28 Finding Next and Previous Search Items 00 00 3 29 Find Pop Up Menu for Global and Local Variables and Attribute Nodes 3 29 Chapter 4 Executing and Debugging Vis and SubVls PXCCUUN ES VAS re ra E aden saeet sceeus caekepen a E R E T TR 4 1 Runnin Vise is r ede t a E ees E T AE eee tees 4 1 SAKOJ eiia es WAS E EEEE EEE T EESTE 4 4 Running VIs Rep atedly eiieeii essri enoe rosii e irse ieee e ey 4 5 Data Logging on the Front Panel eee eee ceecseeceeceseeseceeeeseceeeeeeeeeeaeeeeeeaa 4 5 Retrieving Data Programmatically ec ceeececceeseceeecessecesceceececsaeeeeeenteeesaeeeees 4 7 ACCESSING Databases sirieias aiee Aa a irisi 4 7 Retrieving Data Using File I O Functions ssseeseeeeeeeerreeererereersee 4 9 National Instruments Corporation vij G Programming Reference Manual Table of Contents DO DUS GIN VIS seve aean Sas hs chewecbch a A estan ck Ae EEE a eer E oo oa beste 4 9 Debugging Broken VIS s 2 sccsessscssscestsseesseceescestsssssssnsiadesdsvassoneseaeessgedsSrveesdesaseds 4 9 Interpreting Error Messages cecceeseceececssecenceceneecseceeeeeeseeesaeceaeers 4 11 Corre
442. o not have the capability to rotate text To use rotated text first create it in an application that has this capability such as Windows Paintbrush and save the graphic in a format that can be imported see the Customizing Controls Using Imported Graphics section of Chapter 8 Introduction to Front Panel Objects for more information on importing graphics You can then import this graphic and place it on the y axis of the graph or chart How do I place a text label on a cursor You must first use the Cursor Name Visible attribute to display the cursor name You can then use the Cursor Name attribute to assign a name to the cursor or edit the name in the cursor display of the graph on the front panel National Instruments Corporation B 3 G Programming Reference Manual Appendix B Common Questions about G After I ve added a cursor to my graph how do I remove it You must empty the array that contains the clusters holding the information of each cursor Select Data Operations Empty Array from the pop up menu of the cursor display or write an empty array to the Cursor List Attribute Node programmatically Error Messages and Crashes What should I do when a dialog box appears stating that my application is out of memory LabVIEW and Bridge VIEW allocate memory as needed but arrays and strings must be stored in a contiguous block of memory If your LabVIEW or Bridge VIEW application is unable to find a block of unused memo
443. oad can cause a noticeable loss in performance as the number of individual objects increases An alternative method for storing a large table is to read the table in as a single string Then build a separate array containing the offsets of each record in the string This changes the organization so that instead of having potentially thousands of relatively small blocks of memory you have instead one large block of memory the string and a separate smaller block of memory the array of offsets This method might be more complicated to implement but it can be much faster for large tables G Programming Reference Manual 26 36 National Instruments Corporation Chapter Portability Issues This chapter discusses issues related to transporting VIs between platforms Portable and Nonportable Vis VIs are portable among all the platforms that your application runs on as long as the versions of the application are the same VIs containing CINs or platform specific features such as DDE are not portable In this case a VI ports but it is broken G uses the same file format on all platforms You can transfer VIs from one system to another system either by disk or over a network After the file is on the new system you can open the VI Your application detects that the VI is from another platform and recompiles the VI to use the correct instructions for the current processor If you transfer VIs on a disk formatted for a differen
444. ober 1996 321296A 01 Please comment on the completeness clarity and organization of the manual If you find errors in the manual please record the page numbers and describe the errors Thank you for your help Name Title Company Address Phone __ Fax ___ Mail to Technical Publications National Instruments Corporation 6504 Bridge Point Parkway Austin TX 78730 5039 Fax to Technical Publications National Instruments Corporation 512 794 5678 Glossary Prefix Meaning Value m milli 10 u micro 10 n nano 10 oo Infinity T Pi A Delta Difference Ax denotes the value by which x changes from one index to the next A absolute path Relative file or directory path that describes the location relative to the top level of the file system active window Window that is currently set to accept user input usually the frontmost window The titlebar of an active window is highlighted Make a window active by clicking on it or by selecting it from the Windows menu ANSI American National Standards Institute array Ordered indexed set of data elements of the same type array shell Front panel object that houses an array It consists of an index display a data object window and an optional label It can accept various data types National Instruments Corporation G 1 G Programming Reference Manual
445. objects you need there G Programming Reference Manual 17 10 National Instruments Corporation Chapter 17 Wiring the Block Diagram You can scroll the diagram automatically while you are wiring by dragging the Wiring tool slightly past the edge of the block diagram window Solving Wiring Problems Bad Wires ae When you make a wiring mistake a broken wire which is indicated by a dashed line appears instead of the wire pattern Sometimes you have a faulty wiring connection that is not visible because the broken wire segment is very small or is hidden behind an object If the Run button shows a broken arrow as shown at the left but you cannot see any problems in the block diagram select Edit gt Remove Bad Wires in case there are hidden broken wire segments If the Run button returns to its unbroken state shown at the left you corrected the problem If not click on the Broken Run button to see a list of errors If you do not know why a particular wire is broken pop up on the broken wire and choose List Errors from the pop up menu shown below The Error List dialog box appears and lists the errors Click on one of the errors Doing this selects the erroneous wire which you then can delete or repair List Errors For more information see the Debugging Broken VIs and Debugging Executable VIs sections in Chapter 4 Executing and Debugging VIs and SubVIs National Instruments Corporation 17 11 G Programming Refere
446. odes Table 19 2 Formula Node Errors Continued Error Message Error Message Meaning output variable required Cannot assign to an input variable missing output variable Attempt to assign to a nonexistent output variable missing variable References a nonexistent input or output variable too few arguments Not enough arguments to a function too many arguments Too many arguments to a function unterminated argument list Formula ended before argument list close parenthesis seen missing left parenthesis Function name not followed by argument list missing right parenthesis Formula ended before all matching close parentheses seen missing colon Improper use of conditional ternary operator missing semicolon Formula statement not terminated by a semicolon missing equals sign Formula statement is not a proper assignment G Programming Reference Manual 19 10 National Instruments Corporation Chapter Attribute Nodes This chapter describes how to use Attribute Nodes to set and read attributes of front panel controls programmatically Some useful attributes include display colors control visibility menu strings for a ring control graph or chart plot colors and graph cursors Creating Attribute Nodes You create an Attribute Node by selecting the Create Attribute Node option from the pop up menu of a front panel
447. of the X and Y scale markers respectively You use the remaining three buttons to control the operation mode for the graph Normally you are in standard operate mode indicated by the plus or crosshatch In operate mode you can click in the graph to move cursors around If you press the Panning tool shown to the left you switch to a mode in which you can scroll the visible data by clicking on and dragging sections of the graph If you press the Zoom tool shown at the left you can zoom in on a section of the graph by dragging a selection rectangle around that section If you click on the Zoom tool you see a pop up menu you can G Programming Reference Manual 15 18 National Instruments Corporation ae 4 Unda coom 4 alH Note Chapter 15 Graph and Chart Controls and Indicators use to choose some other methods of zooming This menu is shown in the following illustration Zoom t A description of each of these options follows Zoom by rectangle Zoom by rectangle with zooming restricted to x data the y scale remains unchanged Zoom by rectangle with zooming restricted to y data the z scale remains unchanged Undo last zoom Resets the graph to its previous setting Zoom in about a point If you hold down the mouse on a specific point the graph continuously zooms in until you release the mouse button Zoom out about a point If you hold down the mouse on a specific point the graph
448. of the following ways You can add your own VIs and controls to the palettes by saving them in the user 1ib or instr 1lib directories You can add your own VIs and controls to the palettes by using the Edit Edit Control amp Function Palettes option You can set up the palettes so they automatically change as you add or remove files from specific directories You can rearrange the built in palettes to make the functions you use frequently more easily accessible You can set up different views for different users hiding some functions to make G easier to use for one user while providing the full capabilities for another user Adding Vis and Controls to user lib and instr lib The simplest method for adding new entries to the Controls and Functions palettes is to save them inside of the user 1lib directory When you restart G the User Libraries subpalette of the Functions palette contains subpalettes for each directory 11b or mnu file in user lib and entries for each file in user lib The Instrument I O palette of the Functions palette corresponds to the instr lib directory You might want to put instrument drivers in this directory to make them easily accessible from the palettes Note The vi lib directory contains files from National Instruments Do not save files into vi 1ib because these files are overridden when you upgrade G National Instruments Corporation 7 25 G Programming Reference Manual Chapter 7 Cus
449. of the multiple sources error Two Sequence Structure frames attempt to assign values to the same tunnel The tunnel turns white to signal this error G Programming Reference Manual 18 24 National Instruments Corporation Chapter 18 Structures Wiring underneath Rather than through a Structure To wire through a structure you must click either in the interior or on the border of the structure as shown below If you do not click in the interior or on the border of the structure the wire passes underneath the structure as shown below When the Wiring tool crosses the left border of the structure a highlighted tunnel appears to indicate that the editor will create a tunnel at that location as soon as you click on the mouse button If you continue to drag the tool through the structure without clicking on the mouse until the tool touches the right border of the structure a second highlighted tunnel appears on the right border If you continue to drag the Wiring tool past the right border of the structure without clicking on it both tunnels disappear and the wire passes underneath the structure rather than through it National Instruments Corporation 18 25 G Programming Reference Manual Chapter 18 Structures Examine the following illustration If you tack down the wire inside the structure however the wire goes through the structure even if you continue dragging the Wiring tool past the right border Removing Stru
450. off the increment You have the following options Ignore G does not change or flag invalid values Clicking on the increment and decrement arrows changes the value by the increment you set but the value does not go beyond the minimum or maximum values Coerce G changes invalid values to the nearest valid value automatically For example if the minimum is 3 the maximum is 10 and the increment is 2 valid values are 3 5 7 9 and 10 G coerces the value 0 to 3 the value 6 to 7 and the value 100 to 10 National Instruments Corporation 9 7 G Programming Reference Manual Chapter 9 Numeric Controls and Indicators Suspend G suspends execution of a VI or subVI when a value is invalid When you choose to suspend on invalid values G keeps a copy of all the front panel data in memory in case you need to open the front panel to show an error A top level VI with controls whose values are invalid cannot run If the value of a control is invalid before a subVI runs when a subVI is about to execute the VI is suspended The front panel of the VI opens or becomes the active window and the invalid control s are outlined in red or a thick black line on a black and white monitor The toolbar on the block diagram of a suspended subVI looks like the following illustration Oz F i is You must set the control to a valid value before you can proceed When all control values are valid the toolbar looks like the following illustr
451. ogramming Reference Manual A 4 National Instruments Corporation Appendix A Data Storage Formats The following illustration shows an example of a two dimensional Boolean array G stores the Oth element of each dimension in a new word integer and ignores unused bits from previous dimensions i 1st dimSize n 2nd dimSize k Strings G stores strings as if they were one dimensional arrays of byte integers 8 bit characters rer ear Paths Paths are stored with the path type and number of path components in word integers followed immediately by the path components The path type is 0 for an absolute path and 1 for a relative path Any other value of path type indicates that the path is invalid Each path component is a Pascal string P string in which the first byte is the length in bytes of the P string not including the length byte Clusters A cluster stores elements of varying data types according to the cluster order You store scalar data directly in the cluster Arrays strings handles and paths are stored indirectly The cluster stores a handle that points to the memory area in which the data actually has been stored National Instruments Corporation A 5 G Programming Reference Manual Appendix A Data Storage Formats Because of alignment constraints of certain platforms the dimension size might be followed by a few bytes of padding so that the first element of the data is correctly aligned If yo
452. ol Names to Lowercase 23 12 Create Library Call on Block Diagram 23 10 to 23 11 Default Size for Array Parameters 23 12 to 23 13 illustration 23 10 Include CVI Class Names in VI Names 23 11 Leave VI Front Panels Open 23 10 Use C Function Names for VIs 23 11 to 23 12 Use SubVI for CVI Error Conversion 23 11 conversion process 23 8 to 23 13 CVI Function Panel Converter dialog box Browse button 23 9 Deselect All button 23 10 illustration 23 9 Instrument Prefix text box 23 9 Options button 23 10 Rename button 23 10 Select All button 23 10 purpose and use 23 7 to 23 8 Latch Until Released action 10 6 Latch When Pressed action 10 5 Latch When Released action 10 6 22 13 Left Edges alignment 2 12 legend options for graph indicators 15 19 to 15 22 Bar Plots 15 21 Color 15 22 Common Plots 15 20 to 15 21 G Programming Reference Manual Index Fill Baseline 15 21 Interpolation 15 21 to 15 22 Line Style 15 21 Line Width 15 21 Point Style 15 21 libraries See VI libraries LLBs Limit to Single Line option 11 6 Line Style option 15 21 line tool Icon Editor 3 3 Line Width option 15 21 linefeed character backslash V code table 11 4 entering into string note 11 2 List amp Ring palette 13 1 list box symbol ring constant 16 6 List Errors option 17 11 List of SubVis option Custom Print Settings dialog box 5 6 listbox controls 13 1 to 13 6 Attribute Node example 20 13 to 20 14 creati
453. ol Editor because you are not using the block diagram when you are in Customize mode Control Editor Parts Window To help you size and position control parts select Windows Show Parts Window The floating window that appears identifies the parts of the control and shows you the exact position and size of each part The National Instruments Corporation 22 7 G Programming Reference Manual Chapter 22 Custom Controls and Type Definitions Current Part display in the Parts window displays a picture and the name of the part currently selected in your Control Editor window You can see a menu of all the parts by clicking on the current part display You also can scroll through the parts of the control by clicking on the current part display increment or decrement arrow When you change the part shown in the current part display that part is selected on the control in the Control Editor window When you select change or pop up on another part of the control in the Control Editor window the part showing in the current part display also changes The illustration that follows shows the Control Editor window on the left overlaid by the Control Parts window on the right The name label of the slide is the current part and is selected in the Control Editor window The Control Parts window shows the menu of parts that you see when you click on the current part display This example shows that the name label is the current part but that you are
454. olors Fonts Printing History Time and Date Miscellaneous Path Preferences You can specify the directories that G searches when looking for VIs as well as the paths G uses for temporary files and the library directory If not already selected select Paths from the pull down menu in the Preferences dialog box to bring up the dialog box shown in the following illustration Preferences x Ooo Paths d Library Directory x M Use default CAPROGRAM FILES Cancel G Programming Reference Manual 7 2 National Instruments Corporation Chapter 7 Customizing Your G Environment Note The format of pathnames the use of colons slashes or backslashes differs slightly on different platforms In the Path Preferences dialog box is another pull down menu shown in the following illustration from which you select the path category you want to view or edit Library Directory Temporary Directory Default Directory Vl Search Path In the dialog box that appears many items are grayed out and inactive because G is set to use the default path If you want to change one of these preferences deselect the Use Default checkbox as shown in the following illustration Library Directory Use defaut Library Temporary and Default Directories The Library Directory Temporary Directory and Default Directory are single directories folders When you edit one of these paths you have options to type in a new path
455. om then on will use the new default font Changing the default font does not change the font of existing labels it only affects labels created from that point on 2 16 National Instruments Corporation Chapter 2 Font Dialog Application Font System Font Dialog Font Current Font estity AGaramond AGaramond Bold AGaramond Goldltalic AGaramond Italic AGaramond Semibold Building Vis If you select Font Dialog from the font window while a front panel is active the dialog box shown in the following illustration appears If a block diagram is active instead the dialog box differs only in the selection of Diagram Default instead of Panel Default in the checkboxes at the bottom of the dialog box Panel Default Font Font Application ka x Plain L Bold Size E O tatie O Underline Align C strikeout L outtine coor O Ow The quick brown fox jumps over the lazy dog E Fanel Default O Diagram Default National Instruments Corporation 2 17 G Programming Reference Manual Chapter 2 Building VIs With either the Panel Default or Diagram Default checkbox selected the other selections you make in this dialog box are used with new labels on the front panel or block diagram In the previous illustration the word Application appears in the Font ring This ring also contains the System Font Dialog Font and Current Font options The last option in the ring Current F
456. omatically creates a name for each VI based on either the function panel name or the C function name for each instrument driver option If this option is checked the Class name associated with the LabWindows CVI function panel is prepended to the automatically generated name for the function Use C Function Names for VIs Normally the converter constructs the names of the VIs it generates directly from the function panel item names by merely prepending the instrument prefix and appending vi Unfortunately this approach does not always produce unique names for each item because LabWindows CVI does not require that the leaves of the function 23 11 G Programming Reference Manual Chapter 23 Calling Code from Other Languages G Programming Reference Manual panel tree have unique names Setting this option causes the converter to construct VI names from the actual C function names that the FP items correspond to thereby guaranteeing unique results To avoid problems caused by duplicate names the converter checks to see if all items are unique when it builds the list of function panel items to be displayed Non unique items are flagged with a null symbol and are not selectable by double clicking on them To prevent problems caused by duplicate names the converter brings up a one button alert when it first opens its dialog box if it detects such name conflicts and automatically turns on the Use C Function Names option If you prefe
457. ompiled automatically before they run for the first time after creation or alteration The terminal of a While Loop that contains a Boolean value that determines whether the VI performs another iteration Part of the VI or function node that contains its input and output terminals through which data passes to and from the node Region in the upper right corner of a front panel window that displays the VI terminal pattern It underlies the icon pane See universal constant and user defined constant Execution mode in which a VI is run repeatedly until the operator stops it You enable it by clicking on the Continuous Run button Front panel object for entering data to a VI interactively or to a subVI programmatically Programming system in which the sequential order of instructions determines execution order Most conventional text based programming languages such as C Pascal and BASIC are control flow languages Palette containing front panel controls and indicators Changing the type of a data element The terminal of a For Loop whose value determines the number of times the For Loop executes its subdiagram G 4 National Instruments Corporation CPU current VI custom PICT controls D data acquisition data dependency data flow data logging data storage formats data type descriptor datalog file Description box destination terminal dialog box dimension National Instruments Corporatio
458. on Chapter 1 Introduction to G Programming Front Panel The user interface of a VI is like the user interface of a physical instrument the front panel A front panel of a VI might look like the following illustration Untitled 1 a j EB 1j Spt Application Fant Yj He Yj e Y E Ean Wwaweform zE 8 0 6 0 Fon 40 0 0 7 i 0 50 2 00 Dedek A HEJA The front panel of a VI is primarily a combination of controls and indicators Controls simulate instrument input devices and supply data to the block diagram of the VI Indicators simulate instrument output devices that display data acquired or generated by the block diagram of the VI You add controls and indicators to the front panel by selecting them from the floating Controls palette shown in the following illustration You can switch from the front panel to the block diagram by selecting Windows Show Diagram from the menu National Instruments Corporation 1 3 G Programming Reference Manual Chapter 1 Introduction to G Programming You can change the size shape and position of a control or indicator In addition each control or indicator has a pop up menu you can use to change various attributes or select different options You access this pop up menu by e Windows a
459. on for the library you call to determine which data types to use e Void The type void is only accepted for the return value This option is not available for parameters Use it for the return value if your function does not return any values National Instruments Corporation 23 5 G Programming Reference Manual Chapter 23 Calling Code from Other Languages i Note e Numerics For numeric data types you must indicate the exact numeric type using the data type ring Options include the following Signed and unsigned versions of 8 bit 16 bit and 32 bit integers Four byte single precision numbers Eight byte double precision numbers You cannot use extended precision numbers and complex numbers because they are not generally used in standard libraries You also need to use the format ring to indicate if you want to pass the value or a pointer to the value In Windows 3 1 you cannot use either single precision or double precision data types as the return type This is because there is no standard method for DLLs to return single precision and double precision numbers so this sort of return is implemented differently by each compiler that does it If you need to return a single precision or a double precision number pass the data back as a parameter instead of as the return value e Arrays You can indicate the data type of arrays using the same options as for numeric data types the number of dimensions
460. on in the Search dialog box e Name of a VI Searches for a specific VI only The name of the VI in this ring item depends on the active VI when you invoked the Find dialog box Click on the Find button to begin searching for the text or you have selected Search Results Window After you have completed a search if there is more than one search result the Search Results window displays all search results as shown in the following illustration If only one result is found the result is immediately highlighted bypassing the Search Results window Search Results Search for open Search Results 6 item s found tem Found In Call Instrument vi Panel Ring Data Part Instrument Control Master vi Panel Ring Data Part Instrument Control Master vi Diagram Ring Oota Poart Open Serial Oriver vi Diagram Global Variable Ooata Part Open Serial Oriver vi Diagram Global Variable Data Part Open Serial Oriver vi Diagram Global Variable Data Part bo Te You can display this window also by selecting Project Search Results The following options are available in the Search Results window e Clear Clears and frees memory used to store search results e Go To Highlights the currently selected search result You also can do this by double clicking on the item Items that already have been highlighted are checked e Find Invokes the Find dialog box G Programming Reference Manual 3
461. on option Font Dialog command 2 17 digital displays 9 9 to 9 11 Font Preferences dialog box 7 14 to 7 15 absolute time and date 9 10 to 9 11 Custom font 7 15 example 9 10 Font style 7 15 Format amp Precision dialog box 9 9 illustration 7 15 graph indicators 15 16 to 15 17 Use default font 7 15 Attribute Nodes 20 6 Font ring Numeric formatting 15 16 changing text characteristics 2 16 Scale pop up menu 9 15 Color option 2 17 Time amp Date formatting illustration 2 17 15 16 to 15 17 Justify option 2 17 Formatting option graph indicators 15 15 Size option 2 17 See also X Scale Formatting dialog box Style option 2 17 National Instruments Corporation I 31 G Programming Reference Manual Index Formula Node 19 1 to 19 10 Bakus Naur Form notation 19 8 comments 19 2 definition 19 2 errors table 19 9 to 19 10 floating point numeric scalar variables 19 4 function names table 19 5 to 19 8 input and output variables 19 3 to 19 4 pop up menu 19 3 syntax 19 2 19 8 to 19 9 syntax errors 19 5 Formula Node palette 19 1 frames in Sequence Structures 18 16 free labels 2 14 to 2 16 copying text 2 15 creating 2 14 overlapping controls or indicators note 2 15 Free option 15 35 front panel 1 3 to 1 4 applying changes from custom controls 22 3 to 22 4 building 8 1 to 8 11 control and indicator options 8 2 to 8 4 Controls palette 8 1 to 8 2 customizing dialog box controls 8 9 to 8
462. onfiguring cluster elements 14 20 to 14 23 creating 14 20 data storage formats A 5 to A 7 default values setting 14 21 definition 14 19 disassembling 14 29 to 14 33 Cluster To Array function 14 32 to 14 33 Unbundle By Name function 14 30 to 14 32 Unbundle function 14 29 to 14 30 flattened data A 14 moving 14 22 to 14 23 operating cluster elements 14 20 to 14 23 order of cluster elements setting 14 21 to 14 22 points 14 19 purpose and use 14 19 replacing cluster elements 14 33 resizing 14 22 to 14 23 type definitions 22 22 type descriptors A 11 to A 12 unbundling cluster elements 14 19 wire patterns 14 19 Code Interface Nodes CINs 23 2 coercion dot color setting 7 13 G Programming Reference Manual Index color box illustration 9 24 numeric controls and indicators 9 24 color box constant 16 6 Color Copy tool 2 5 color icons vs black and white 3 3 color mapping options intensity chart 15 40 to 15 41 Color option Font ring 2 17 graph indicators 15 22 Color palette illustration 2 24 More option 2 25 Color Preferences dialog box 7 13 to 7 14 Blink Background 7 14 Blink Foreground 7 14 Block Diagram 7 13 Coercion Dots 7 13 Front Panel 7 13 illustration 7 13 Menu Background 7 14 Menu Text 7 13 Provide extra colors 7 14 Scrollbar 7 13 Use default colors 7 14 color ramp 9 25 to 9 26 Color Table Attribute 15 40 to 15 41 Color tool 2 5 coloring objects 2 24 to 2 26 copy
463. ont refers to the last font style selected G uses the Application System and Dialog fonts for specific portions of the interface These fonts are predefined by G so that they map best between platforms When you take a VI that contains one of these fonts to another platform G ensures that the font maps are exchanged appropriately The predefined fonts are as follows e Application font is the G default font It is used for the Controls palette the Functions palette and text in new controls e System font is the font used in G for menus e Dialog font is the font used for text in dialog boxes If you click the Panel Default and Diagram Default checkboxes the selected font becomes the current font for the front panel the block diagram or both The current font is used on new labels You can use the checkboxes to set different fonts for the front panel and block diagram For example you can have a small font on the block diagram and a large one on the front panel For information on portability issues regarding the three types of fonts see the Resolution and Font Differences section in Chapter 27 Portability Issues For information on changing the defaults for the three categories of fonts see the Font Preferences section in Chapter 7 Customizing Your G Environment The Font ring also has Size Style Justify and Color options as shown in the following illustration G Programming Reference Manual 2 18 National Instru
464. ontrols are used to present users with a list of options An example is shown in the following illustration There are two types of listbox controls Single Selection in which only one option can be National Instruments Corporation 13 1 G Programming Reference Manual Chapter 13 List and Ring Controls and Indicators selected and Multiple Selection in which one or more options can be selected instrument Multimeter Oscilloscope Digitizer Digital Plotter Counter Calibrator Power Supply Function Generator In addition to displaying a list of text options you can have one of several different symbols drawn next to each item as in the Save dialog box where directories and files have different symbols You can detect the currently selected option s by reading the value of the control By using an Attribute Node you also can detect which item if any the user double clicked on Finally you can choose to have some options grayed out non selectable using the Attribute Node Creating a List of Options When you put a listbox on a front panel it contains no text You can create the list of options in edit mode by typing them with the Labeling tool or in run mode by using the Attribute Node Separate individual options by entering a carriage return If you can determine the options when you create the VI you might want to type in the options while in edit mode If you can determine the options at run time for example
465. oose to read or to set attributes by selecting either the Change to Read or Change to Write option from the Attribute Node pop up menu as shown in the illustration that follows G Programming Reference Manual 20 2 National Instruments Corporation Chapter 20 Attribute Nodes You can set an attribute when the small direction arrow is located on the left side of the terminal You can read an attribute when the arrow is located on the right side of the terminal Change All To Read Find gt diygiiveds Hajr Show direction arrow Replace Description Change To Read Select Item Add Element HaayyEdnarda piprmeni Create Constant Create Control Create Indicator Show Full Names You can read or set more than one attribute with the same node by enlarging the Attribute Node New terminals are added as the node enlarges a ible 1 pisible f Wisible Disabled Format amp Precision Precision i National Instruments Corporation 20 3 G Programming Reference Manual Chapter 20 Attribute Nodes You associate a terminal with a given attribute by clicking on the terminal with the Operating tool and selecting an attribute from the Attribute Node pop up menu Po Wisible Disabled T Format amp Pred Disabled Key Focus Format amp P Text Colors Precision i You can create more than one Attribute Node by cloning an existing node or by selecting the Create Attribute Node option again To clo
466. op Up menu 3 20 National Instruments Corporation hiding digital displays 2 13 labels 2 13 menu bar 6 6 B 15 Stop button 4 4 toolbar 6 6 hierarchy node mouse clicks sequences 3 21 to 3 22 Hierarchy Node Pop Up menu Edit Icon option 3 21 Get Info option 3 21 Hide All SubVIs option 3 20 Highlight Connections option 3 20 Open Front Panel option 3 21 Print Documentation option 3 21 Show All Callers option 3 21 Show All SubVIs option 3 21 Show Immediate SubVIs option 3 20 Show VI Hierarchy option 3 20 VI Setup option 3 21 hierarchy of VI printing 5 6 Hierarchy window 3 15 to 3 23 features 3 15 Find Hierarchy Node mechanism 3 22 to 3 23 node mouse click sequences 3 21 to 3 22 node pop up menu options 3 20 to 3 21 opening 3 15 to 3 17 subVI connections to calling VIs 3 16 to 3 17 toolbar buttons 3 19 View menu options 3 18 to 3 19 viewing during suspended execution 4 30 Highlight Connections option 3 20 highlighting execution 4 21 to 4 23 auto probe during 7 12 example 4 22 execution glyphs 4 23 Hilite Execution button 4 21 showing data bubbles 7 12 Hilite lt Return gt Boolean option 6 5 Hilite Execution button 4 21 National Instruments Corporation l 35 Index history for VIs See Vi history VI History window History Preferences dialog box 7 17 to 7 20 Add an entry every time VI is saved 7 18 illustration 7 18 Login automatically with the system user name 7 20 Prompt
467. opy of that control called a type definition When you make a change to the type definition you automatically update all the VIs that use it The following sections explain how to make these and other custom alterations to controls Custom Controls Using the Control Editor Make certain that you are in edit mode to customize a control On the front panel place a control that is most like the one you want to create For example to create a slide with its scale on the right start by placing any vertical slide on the front panel With the Positioning tool select the slide control and then choose Edit Edit Control This option is available only when you have National Instruments Corporation 22 1 G Programming Reference Manual Chapter 22 edit mode Custom Controls and Type Definitions customize mode selected a control You can edit only one control at a time from a front panel Fao Edit Control A window opens displaying a copy of the control This window shown in the following illustration is called the Control Editor and it is titled Control N which is the name assigned to the Control Editor window until you save the control and assign it a permanent name Control 1 a 100 0 E aj 6 0 4 0 2 0 00 5 The Control Editor window looks like a front panel but it is used only for editing and saving a single control it has no block diagram and cannot run A Control Editor has
468. or a function or subVI the description of controls and indicators the values of universal constants and descriptions and data types of control attributes The window also accesses the Online Reference for G Hexadecimal A base 16 number system G 7 G Programming Reference Manual Glossary hierarchical palette Hierarchy window housing icon Icon Editor icon pane IEEE indicator Inf inplace execution instrument driver I O iteration terminal G Programming Reference Manual Menu that contains palettes and subpalettes Window that graphically displays the hierarchy of VIs and subVIs Nonmoving part of front panel controls and indicators that contains sliders and scales Hertz Cycles per second Graphical representation of a node on a block diagram Interface similar to that of a paint program for creating VI icons Region in the upper right corner of the front panel and block diagram that displays the VI icon Institute for Electrical and Electronic Engineers Front panel object that displays output Digital display value for a floating point representation of infinity Ability of a function or VI to reuse memory instead of allocating more VI that controls a programmable instrument Input Output The transfer of data to or from a computer system involving communications channels operator input devices and or data acquisition and control interfaces The terminal of a For Loop or While
469. or and enter the new value or click on the appropriate arrow key to increase or decrease the current value After entering the new value press the lt Enter gt key on the numeric keypad to see the results in the color rectangle To alter one of the base colors click on the color rectangle and choose one of the National Instruments Corporation 2 25 G Programming Reference Manual Chapter 2 Building VIs selections The component values for the selected color appear in each display The last color you select from the palette becomes the current color Clicking on an object with the Color tool sets that object to the current color You also can copy the color of one object and transfer it to a second object without using the Color palette Click with the Color Copy tool lt Ctrl click gt Windows lt command click gt Macintosh lt meta click gt Sun or lt Alt click gt HP UX with the Color tool on the object whose color you want to duplicate The Color tool appears as an dropper and takes on the color of the selected object Now you can click on another object with the Color tool and that object becomes the color you have chosen Creating Object Descriptions If you want to enter a description of a G object such as a control or indicator choose Data Operations Description from the object s pop up menu You must be in edit mode to edit a description Enter the description in the dialog box shown in the follow
470. or and filled with the background color Double click to frame the icon in the foreground color and fill it with the background color Use the lt Shift gt key to constrain the rectangle to a square select Selects an area of the icon for moving copying or deleting Double click on the entire icon to select it Double click on the entire icon and then press the lt Delete gt key to erase it Use the lt Shift gt key to constrain the rectangle to a square text Enters text into the icon Double click on this tool icon to select a different font foreground background Displays the current foreground and background colors Click on each to get a palette from which you can choose new colors Holding down the lt Ct r1 gt Windows lt opt ion gt Macintosh lt meta gt Sun or lt Alt gt HP UX key temporarily changes all of the tools except the select tool to the dropper The buttons to the right of the editing screen perform the following functions when you click on them Undo Cancels the last operation you performed in the Icon Editor OK Saves your drawing as the VI icon and returns to the front panel Cancel Returns to the front panel without saving any changes iz Note You can cut copy and paste the entire icon using these options from the menu or pressing lt Ctrl gt Windows lt command gt Macintosh lt met a gt Sun or lt Alt gt HP UX plus x for cut c for copy and v for paste
471. ormance and Disk dialog box 7 7 Use default timer 7 7 to 7 8 Printing Preferences dialog box 7 16 to 7 17 Allow printer dithering 7 16 Bitmap printing 7 17 illustration 7 16 PostScript printing 7 16 to 7 17 National Instruments Corporation 1 45 Index Scale printer fonts 7 16 Standard printing 7 16 Time and Date Preferences dialog box 7 21 Date Separator 7 21 Default date format 7 21 Default time format 7 21 illustration 7 21 Time Separator 7 21 Print at Completion option 5 7 Print Documentation dialog box See also Custom Print Settings dialog box choosing layout options Page Breaks Between Sections 5 4 Print Header 5 4 Scale Block Diagram to Fit 5 4 Scale Front Panel to Fit 5 4 Configure button 5 4 illustration 5 3 setting print formats Complete Documentation format 5 4 25 9 Custom format 5 4 Icon Description Panel and Diagram format 5 3 Using as a SubVi format 5 3 Using the Panel format 5 3 Print Documentation option 3 21 5 1 5 2 Print Header option 5 4 Print Panel When VI Complete Execution option 5 8 Print Section Headers option Custom Print Settings dialog box 5 6 Print Window option 5 1 5 2 Printer Setup option 5 1 printing in G questions about B 4 B 7 to B 9 Printing Preferences dialog box 7 16 to 7 17 Allow printer dithering 7 16 Bitmap printing 7 17 illustration 7 16 PostScript printing 7 16 to 7 17 Scale printer fonts 7 16 Standard printing 7 16
472. orporation Index patterns defining 3 5 selecting and modifying 3 6 required recommended and optional connections 3 8 to 3 9 white terminal indicating incomplete connection note 3 8 terminals See also tunnels conditional terminal 18 4 control and indicator terminals 16 2 to 16 3 symbols 16 2 to 16 3 count terminal 18 3 definition 16 1 destination terminals 16 1 displaying 16 1 front panel terminals avoiding cycles in subVIs 3 13 created automatically 2 3 to 2 4 indicator terminals 16 1 iteration terminal 18 3 node input terminals 16 1 overview 1 4 to 1 5 placing inside For and While loops 18 6 to 18 7 selector 18 14 shift register terminals 18 10 sink terminals 16 1 source terminals 16 1 types of 16 1 text changing fonts 2 16 to 2 22 dragging and dropping 2 8 to 2 9 finding 3 26 to 3 27 menu text color 7 13 numeric scale text labels 9 18 to 9 19 min and max labels 9 18 to 9 19 ring controls adding text 13 8 to 13 9 changing text 13 10 text display pop up menu 9 19 Text Labels option 9 18 text parts 22 14 to 22 15 G Programming Reference Manual Index text tool Icon Editor 3 4 This Connection Is submenu 3 8 to 3 9 This VI s SubVIs option 4 16 three dimensional arrays 14 11 Time and Date Preferences dialog box 7 21 Date Separator 7 21 Default date format 7 21 Default time format 7 21 illustration 7 21 Time Separator 7 21 time formatting absolute digital displays
473. ort a picture you change only the current picture item To import a picture for one of the other picture items first select that picture item and then import the new picture Cosmetic Parts with Independent Pictures A cosmetic part with more than one picture can have pictures of different sizes which each use different colors The slide for example uses two pictures of different sizes to show which slider is active on a multi value slide The slide in the following example uses a bigger triangle to show that the middle slider is the active one G Programming Reference Manual 22 12 National Instruments Corporation Chapter 22 Custom Controls and Type Definitions A Boolean switch also has more than one picture Each picture can be a different size and have different colors A Boolean switch has four different pictures the first shows the false state the second shows the true state You use the third and fourth pictures when you set the mechanical action of a Boolean control to either Switch When Released or Latch When Released Until you release the mouse button the value of the Boolean does not change with these two mechanical actions Between the time you click on the button and the time you release the click the Boolean shows the third or fourth picture as an intermediate state The third picture is for the true to false transition state and the fourth is for the false to true state In the following illustration of a toggle
474. ortcut 4 20 lt meta b gt removing bad wires 4 10 lt meta click gt copying and transferring colors 2 26 executing Show VI Hierarchy action 3 21 resizing working space 2 24 untacking last tack point note 17 3 lt meta f gt bringing up Find dialog box 3 24 lt meta h gt help key 1 7 lt meta m gt switching from run mode to edit mode note 6 6 lt meta Return gt embedding newlines 7 10 lt meta Shift gt bringing up temporary Tools palette 2 4 min and max labels numeric scales 9 18 to 9 19 Miscellaneous Preferences dialog box 7 22 to 7 23 Allow drop through clicks 7 23 illustration 7 22 Open VIs in run mode 7 22 Show tips strips 7 22 Use hot menus 7 23 Use native file dialogs 7 22 mouse disabling mouse interrupts B 16 mouse click sequences for hierarchy node selection 3 21 to 3 22 symbol for wiring block diagrams 17 1 Move Backward command 2 11 Move Forward command 2 10 Move Submenu option 7 29 Move To Back command 2 11 Move To Front command 2 10 moving See also positioning objects arrays 14 14 between subdiagrams 18 18 to 18 19 clusters 14 22 to 14 23 G Programming Reference Manual Index graph cursors 15 32 wires 17 6 to 17 10 multidimensional arrays description 14 4 displaying 14 10 when to use 14 4 multiple developers of VIs See applications managing multiple selection using selection rectangle 2 7 to 2 8 multiplot graphs See waveform and XY graphs multitask
475. ou start LabVIEW or Bridge VIEW For example to use a file named 1vrc instead of labview ini type labview pref lvrc National Instruments Corporation 7 23 G Programming Reference Manual Chapter 7 Customizing Your G Environment Macintosh You can create a LabView Preferences file in your System Folder that contains preference information Under System 6 this preference file is created at the top level of the System Folder however under System 7 it is created in the Preferences folder of the System Folder If you want you can copy your LabVIEW Preferences file to the LabVIEW folder When launched LabVIEW always looks for the Preferences file in the LabVIEW folder If not found there it looks in the System Folder and if not found there it creates a new one in the System Folder By moving Preferences files between desktop and the LabVIEW folder you can create multiple Preferences for multiple users or uses UNIX Preference information normally is stored in a source file in your home directory If you change a parameter from the Preferences dialog box G writes the information to this file The following information is supplied for those who want more information on the storage format and the rules for finding preference information Preference entries consist of a preference name followed by a colon and a value The preference name is the executable name followed by a period and a token When LabVIEW searches for prefe
476. ou edit a scale and enter only time or only date the unspecified components are inferred If you do not enter time when editing it assumes 12 00 a m If you do not enter a date the previous date value is assumed If you enter date but the scale is not in a date format the month day and year G Programming Reference Manual 15 16 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators ordering are assumed based on the settings in the Preferences dialog box If you enter only two digits for the year the following is assumed any number less than 38 is in the twenty first century otherwise the number is in the twentieth century Although absolute time is displayed as a time and date string it is represented internally as the number of seconds since 12 00 a m January 1 1904 Universal Time Note When a scale is in absolute time format you always have the option to enter time date or time and date If you do not want G to assume a date use relative time Notice the examples at the top right of the dialog box which change as you make selections The valid range for time and date differs across computer platforms as follows e Windows 12 00 a m Jan 2 1970 12 00 a m Feb 4 2106 e Windows NT 12 00 a m Jan 1 1970 12 00 a m Jan 3 2040 e Macintosh 12 00 a m Jan 2 1904 12 00 a m Jan 2 2040 e UNIX 12 00 a m Dec 15 1901 12 00 a m Jan 17 2038 These ranges
477. ou enter an integer or a double precision complex number if you enter a complex number For example the representation is long integer if you enter 123 anda double precision floating point number if you enter 123 You can change the representation with the Representation option from the constant pop up menu Universal Constants Universal constants are of two types universal numeric constants and universal string constants e Universal numeric constants Set of high precision and commonly used mathematical and physical values such as pi and the speed of light e Universal string constants Set of commonly used nondisplayable string characters such as line feed and carriage return National Instruments Corporation 16 7 G Programming Reference Manual Chapter 16 Nodes Introduction to the Block Diagram For more information on these constants see Online Reference Function and VI Reference Nodes are the execution elements of a block diagram The six types of nodes are functions subVIs structures Code Interface Nodes CINsS Formula Nodes and Attribute Nodes Functions and subVI nodes have similar appearances and roles in a block diagram but they have substantial differences They are explained in the following sections CINs are interfaces between the block diagram and code you write in conventional programming languages such as C or Pascal If you are a LabVIEW user refer to the LabVIEW Code Interface Refere
478. ound the item in the palette National Instruments Corporation 2 11 G Programming Reference Manual Chapter 2 Building Vis e Top Edges Aligns all top edges of the selected objects with the topmost object e Vertical Centers Aligns the objects at the point halfway between the topmost and bottommost objects e Bottom Edges Aligns all bottom edges of the selected objects with the bottommost object e Left Edges Aligns all left edges of the selected objects with the object that is farthest to the left e Right Edges Aligns the edges of the selected objects with the object that is farthest to the right e Horizontal Centers Aligns the objects at the point halfway between the farthest to the left object and the farthest to the right object Distributing Objects To space objects evenly or distribute them select the objects you want to distribute and choose how you want to distribute them from the Distribution ring In addition to distributing selected objects by making their edges or centers equidistant four options at the right side of the ring let you add or delete gaps between the objects horizontally or vertically Duplicating Objects There are three basic methods for duplicating a G object by copying and pasting by cloning and by dragging and dropping In all cases you can create a new copy of the object complete with its associated elements such as the terminal belonging to a front panel control or the
479. ow Preferences Are Stored onies e R EE E 7 23 Customizing the Controls and Functions Palettes 00 0 ce ee eceeeeeeeseeeeeeecsecnseeseenaee 7 25 Adding VIs and Controls to user lib and instr lib eee eeeeeeeeeeeeeeeee 7 25 Installing and Changing Views 0 0 cece cseseecsecssecseceseeseceseeseceseeseeeeeeaeeeeeeaa 7 26 Palettes EGitotts eeni enee eer e a obanteon sos gneve antes ty E N S 7 26 Creating Subpalettes 00 eee ceecseesseceeceseeseceseeeceeeeeeseeeeeeseneeaes 7 27 Moyin Subpalettes soeren ennei iee ni peewee 7 29 How Views WOK eein ren i r E TEE AE 7 29 National Instruments Corporation ix G Programming Reference Manual Table of Contents Front Panel Objects Chapters 8 through 15 Chapter 8 Introduction to Front Panel Objects Building the Front Panelics i cs csseiscs sasseiiages cbs schsees shaesssety hens sneey daaserpessabessenssetenven captors 8 1 Front Panel Control and Indicator Options eee ce cess ceseeeeceeeeeeeeeeeeeeene 8 2 Replacing Controls s c s csessssessceestes sas nscestepsiosssevcsejaos seb sseascvassepescseass 8 4 Key Navigation Option for Controls eee cesses ceseeseceeeeeeeeeeeeeseeeeaeeeaeeaee 8 5 Panel Order Optlone ss sires scisedvevensavsevsseacsvaaessbacsee ives sous E Ea EE E na EE r EEES 8 8 Customizing Dialog Box Controls s seeseseeseseseeseseeresrestsresrrreereeresreresrsresessee 8 9 Customizing Controls Using Imported Graphics sseseseseesesseeesreereererrsrssrsrssrrr
480. owing illustration the y variable and the z variable must both be declared as outputs You can change an input to an output by selecting Change to Output from the pop up menu as shown in the following illustration y 3 x 2 x logix Remove You can change an output to an input by selecting Change to Input from the pop up menu as shown below y 3 x 2 x logix All variables are floating point numeric scalars whose precision depends on the configuration of your computer Variables cannot have units All input variables that appear in the formulas must be wired All output variables that are wired must be assigned in at least one statement that is they must be on the left side of an equal sign An G Programming Reference Manual 19 4 National Instruments Corporation Chapter 19 Formula Nodes output variable might appear in an expression on the right side of an equal sign but G does not veify if it has been assigned in a previous statement When an assignment occurs as a subexpression the value of the subexpression is the value assigned for example x sin y pi 3 T assigns to y and then assigns sin to x If a syntax error occurs you can click on the Broken Run button to see the error listing In the listing the Formula Node displays a portion of the formula with a symbol marking the point at which the formula box detected the error Formula Node Functions and Operators All function n
481. ows during suspension 4 30 sweep chart update mode 15 26 to 15 27 Switch Until Released action 10 5 Switch When Pressed action 10 5 Switch When Released action 10 5 22 13 symbols for listbox items 13 4 Synchronize with Directory option 7 28 system crashes questions about B 4 to B 5 National Instruments Corporation System Default suboption Keyboard Mode option 13 6 System Exec VI 5 1 23 1 System font 2 18 T tab character backslash lt V code table 11 4 entering into string note 11 2 lt Tab gt key moving between array elements 14 13 moving between cluster elements 14 21 moving between tools in Tools palette 2 5 string controls and indicators note 11 2 toggling between Positioning and Scroll tools 3 22 tables 11 6 to 11 9 copying cutting and pasting data 11 8 entering and selecting data tables 11 7 to 11 9 illustration 11 6 manipulating with string functions 11 9 resizing tables rows and columns 11 6 to 11 7 row and column headings 11 9 Selection Scrolling option 11 8 showing selected area of data 11 9 technical support C 1 to C 2 temporary directories setting 7 3 to 7 4 terminal connections for subVIs 3 5 to 3 10 assigning to controls and indicators 3 6 to 3 8 changing spatial arrangement 3 6 confirming terminal connections 3 9 to 3 10 deleting terminal connections 3 9 to 3 10 limiting number of when creating subVI from selections 3 12 National Instruments C
482. p menu National Instruments Corporation 9 33 G Programming Reference Manual Chapter 9 Numeric Controls and Indicators for the broken wire shown below the List Errors window indicates that the error is Wire unit conflict Some functions are ambiguous with respect to units and cannot be used with signals that have units For example the Add One function is ambiguous with respect to units If you are using distance units Add One cannot tell whether to add one meter one kilometer or one foot Because of this ambiguity the Add One function and similar functions cannot be used with data that has associated units One way around this difficulty is to use a numeric constant with the proper unit and the addition function on the block diagram to create your own Add One unit function distance 1 i Note You cannot use units in Formula Nodes G Programming Reference Manual 9 34 National Instruments Corporation Chapter 9 Numeric Controls and Indicators Polymorphic Units If you want to create a VI that computes the root mean square value of a waveform you have to define the unit associated with the waveform A separate VI is necessary for voltage waveforms current waveforms temperature waveforms and so on In order to have one VI to do the same calculation regardless of the units received by the inputs G has polymorphic unit capability Create a polymorphic unit by entering x where x is a number for example 1
483. p strips over terminals 7 11 Show wiring guides 7 11 G Programming Reference Manual Index block diagrams 16 1 to 16 13 See also wiring block diagrams pop up menu 10 3 push buttons simulation 10 2 G Programming Reference Manual color settings 7 13 components of 16 1 constants 16 3 to 16 8 control and indicator terminals 16 2 to 16 3 displaying 2 4 functions 16 8 to 16 11 help information 1 7 to 1 9 inserting objects 16 12 labels for subVIs note 2 16 nodes 16 1 16 8 to 16 12 overview 1 4 to 1 5 placing and sizing structures on 18 5 to 18 6 printing Block Diagram option 5 6 Hidden Frames option 5 6 Repeat Higher Level Frames option 5 6 replacing objects 16 12 resizing work space 2 24 structures 16 11 to 16 12 terminals 1 4 to 1 5 16 1 to 16 8 Boolean controls and indicators 10 1 to 10 6 Attribute Node example 20 11 to 20 12 changing labels 10 3 to 10 4 customizing with imported pictures 10 6 data range checking 10 4 Hilite lt Return gt Boolean option 6 5 illustration 10 1 LED simulation 10 2 light simulation 10 2 mechanical action configuration 10 4 to 10 6 Latch Until Released action 10 6 Latch When Pressed action 10 5 Latch When Released action 10 6 Mechanical Action palette 10 4 to 10 5 Switch Until Released action 10 5 Switch When Pressed action 10 5 Switch When Released action 10 5 slide switch simulation 10 2 stopping on Boolean value
484. panel objects to the default 1 000 milliseconds or a speed that you type in Blinking is a basic attribute turned on with Attribute Nodes See Chapter 20 Attribute Nodes for more information G Programming Reference Manual 7 10 National Instruments Corporation Chapter 7 Customizing Your G Environment Note Changes to options in the Front Panel Preferences dialog box take effect immediately Block Diagram Preferences The Block Diagram Preferences dialog box is shown in the following illustration Preferences Block Diagram v C Show dots at wire junctions Show tip strips over terminals Show wiring quides C Show sub I names when dropped The options in this dialog box are as follows Show dots at wire junctions Directs G to place dots where two wires cross making it easier to differentiate between such junctions and wires that branch Show tip strips over terminals Directs G to place parameter names over terminals when you idle your cursor over them in functions and subVIs Show wiring guides Shows wire stubs that indicate data type and data direction for each parameter when the cursor is idled over a block diagram node Show subVI names when dropped Directs G to label a subVI with the name of the original VI when you drop it on the block diagram and to show the label National Instruments Corporation 7 11 G Programming Reference Manual Chapter 7 Customizing Your G Environment ie Note Change
485. particularly useful in larger applications in conjunction with type definitions By defining a cluster that might change as a type definition any VI that uses that control can be changed to reflect a new data type by updating the file of the type definition If the VIs use only Bundle By Name and Unbundle By Name to access the National Instruments Corporation 14 27 G Programming Reference Manual Chapter 14 Array and Cluster Controls and Indicators elements of the cluster you can avoid breaking the VIs that use the cluster See the Type Definitions section of Chapter 22 Custom Controls and Type Definitions for more information on type definitions Also see the Unbundle By Name Function section of this chapter Array To Cluster Function Array To Cluster The Array To Cluster function which you select from the Array palette uneton of the Functions palette converts the elements of a 1D array to elements of a cluster This function is useful when you want to display elements within a front panel cluster indicator but you also want to manipulate the elements by index value on the block diagram Use the Cluster Size option from the function pop up menu to configure the number of elements in the cluster The dialog box that appears is shown in the following illustration Cluster Size Number of elements in cluster The function assigns the Oth array element to the Oth cluster element and so on If the array contains mor
486. pixel in the picture More complex pictures might contain any number of commands that are executed every time the picture is drawn Pictures containing drawing commands are created by drawing programs or in the draw layer of a graphics application Bitmap based pictures are created by paint programs or in the paint layer of a graphics application G Programming Reference Manual 27 4 National Instruments Corporation Chapter 27 Portability Issues Bitmaps are common storage formats for pictures on all platforms If you use pictures that contain bitmaps on your front panels the pictures usually look the same when you load your VIs on another platform However pictures containing drawing commands might include some commands that are not supported on other platforms for example clipping and pattern filling These pictures might look strange on other platforms Check how your VIs look on another platform if you expect them to be used there You still can use a drawing program or the draw layer of a graphics application to create your pictures But to make them more portable paste the final picture into a paint program or into the paint layer of a graphics application before importing the picture Windows 95 NT and Macintosh With some applications on Windows 95 NT and many graphics applications on Macintosh you can cut or copy a picture with a non rectangular shape In Macintosh for example you can use a Lasso tool like the one shown at t
487. played during the transitional state National Instruments Corporation 20 11 G Programming Reference Manual Chapter 20 Attribute Nodes You can set the display strings for the Switch controls to the string choices Stop Run and Stop and Run The following illustration shows how to set the display strings Block Diagram Front Panel STOP Run STOP Strings 4 Setting the Strings of Ring Controls The ring control is a pop up menu control that holds the numeric value of the currently selected item You can use it to present the user with a list of options If the options cannot be determined until run time you can use the Attribute Node to set the options See Chapter 13 List and Ring Controls and Indicators for more information about ring controls In the following example the user is presented with a panel that has a ring control which displays a list of tests The user selects a test and then presses the Execute Test button to continue select a test LI Execute Test The block diagram shown in the illustration that follows reads a list of valid tests from a file and passes the list represented as an array of strings to an Attribute Node for the ring control The diagram then G Programming Reference Manual 20 12 National Instruments Corporation Chapter 20 Attribute Nodes loops waiting for the user to click on the Execute Test button This gives the user a chance to select
488. ples on graphs and charts in the general graphs directory What is the basic difference between charts and graphs Charts and graphs differ in the way they display and update data VIs with graphs usually collect the data in an array and then plot it on the graph similar to a spreadsheet that first stores the data then generates a plot of it In contrast a chart appends new data points to those already in the display In this manner you can see the current reading or measurement in context with data previously acquired The length of the chart history buffer can be set by a pop up option on the chart Of course it is possible to implement a history buffer with the graph indicators as well however this needs to be done in the block diagram These features are already built into the chart How do flip the scales on my chart or graph To flip the scales for the x axis or y axis use the attribute X Flipped or Y Flipped If the X Flipped attribute is set to TRUE then the minimum of the x axis scale is set to the right and the maximum to the left Similarly if the Y Flipped attribute is set to TRUE the minimum of the y axis scale is at the top and the maximum is at the bottom National Instruments Corporation B 1 G Programming Reference Manual Appendix B Common Questions about G How do make a chart or graph display information in a time format Graphs and charts can display numeric information in a relative time format Us
489. plication uses the same font as the System font UNIX The application normally uses Helvetica for this font On HP UX this font is the same as the System font When you take a VI that contains one of these fonts to another platform your application ensures that the font maps to something similar on that platform If you do not use the predefined fonts but instead select a specific font such as Geneva or New York the font can change size on the new platform because of the differences in the fonts available and differences in the resolution of the display If you select Geneva or New York on the Macintosh the application cannot match it on the Sun or HP UX and the application uses the font named fixed If you take a VI with unrecognized fonts to Windows you might not have a good mapping to a new font National Instruments Corporation 27 3 G Programming Reference Manual Chapter 27 Portability Issues If you use a predefined font on a section of text National Instruments recommends that you do not change the size of that text If you change the font to something other than the default size and then take the VI to a different platform the application tries to match the font with the new size which might be inappropriate given the resolution of the screen For example an application font with size 10 one pixel bigger than the default looks good on the Macintosh Geneva 10 but looks very tiny on Windows with a high resolution
490. ption cece eseeesecseesseceeceseceeeseeseenseeseeees 11 5 Hex Display Option sneseno ieee eere errie esris e 11 5 Limitto Single line Option sce c0sseceseseesdsadechsossnesscbsos cusegenssbogsdyeven ieniyer teesgpeees 11 6 EADIOS ES cess Rese opel EAS A A Eine cee ek ER ee Ne 11 6 Resizing Tables Rows and Columns ecessssesceceeceeeceececesecesceceeeecneeeeneens 11 6 Entering and Selecting Data Tables o0 cece ceeceseeeeeeseeeeceeeeeeseneeeeseneeaee 11 7 Chapter 12 Path Controls and Indicators and Refnums Path Controls atid Indicators esac ccsvesesies secs sincegenevecens ecuecsvlecvowevscetvsevtten at cchwestnevevneettesosebes 12 1 RA DnA ia n AARRE E eee ad kv eect even ieee dee T 12 2 Chapter 13 List and Ring Controls and Indicators Eistbox Controls raen eeN E E RE E EE 13 1 Creating a List of Options ssseesessesesssresessstsresrerrsreersreerereesesrnrerresreesrentsreneees 13 2 Selecting Listbox Itenser eneeier aaeeea s a ES sieve eee 13 2 Listbox Data T Pesna rone e T AE INTE NIE EEEE SESTE 13 3 National Instruments Corporation xi G Programming Reference Manual Table of Contents Listbox Pop Up Menu Options 0 0 cece ceeesecseceseeseceseeseceeceseeeeeeeesenseaeeenenes 13 3 SHOW EEEE dee scea eck aug ses ETETE 13 4 Selection Mode iii coi iese el He whee hice E EE KOERTE s 13 4 Keyboard Modes niisiis eie 13 6 Creating a Grayed Out Dividing Line 0 elec cee ceseeeeceseeeeceeeeeeseneeeeeene 13 6 Ring
491. ption cosmetic parts pop up menu 22 11 File menu 2 28 3 11 G Programming Reference Manual Index revision numbers for VIs purpose and use 25 7 to 25 8 showing 7 19 25 8 Right Edges alignment 2 12 ring constants 16 6 ring controls 13 7 to 13 10 adding items pictures 13 9 text 13 8 to 13 9 Attribute Node example 20 12 to 20 13 changing size and text 13 9 purpose and use 13 7 to 13 8 styles 13 7 rotary numeric controls and indicators 9 21 to 9 23 illustration 9 21 operating and modifying 9 22 to 9 23 Rotate 90 Degrees command 3 6 TOWS headers 11 6 resizing 11 6 to 11 7 Run button executing VIs 4 1 using during suspended execution 4 30 VI caller is running 4 2 VI running at top level 4 2 Run command 4 1 Run Continuously button 4 1 4 5 Run When Opened option 6 2 running VIs 4 1 to 4 4 See also executing VIs buttons for running 4 1 editing while running 4 2 to 4 4 control pop up menu options 4 2 to 4 3 object pop up menu options 4 3 to 4 4 loading and running dynamically B 10 multiple VIs 4 2 running repeatedly 4 5 switching from run mode to edit mode note 6 6 run time VIs 25 2 to 25 4 G Programming Reference Manual S Save a Copy As option 2 28 Save As option 2 28 22 4 Save option 2 28 22 20 Save With Options option 2 28 Save with Options option 25 3 to 25 4 saving custom controls 22 4 saving type definitions 22 20 saving VIs 2 27 to 2 30 avoiding vi lib direc
492. put the output unit is computed as m 2 s 2 If this VI receives inputs of m to the 1 input and kg to the 1 s input however one of the inputs is declared to be a unit conflict and the output is computed if possible from the other A polymorphic VI can have a polymorphic subVI because the respective units are kept distinct National Instruments Corporation 9 35 G Programming Reference Manual Boolean Controls and Indicators This chapter discusses how to create operate and configure Boolean controls and indicators Creating and Operating Boolean Controls and Indicators A Boolean control or indicator has two values TRUE or FALSE Boolean controls and indicators are available from the Controls Boolean palette as shown in the following illustration oe Cancel e amp National Instruments Corporation 10 1 G Programming Reference Manual Chapter 10 Boolean Controls and Indicators Some Boolean controls that simulate mechanical pushbuttons toggle switches and slide switches are shown in the following illustration Round Button Labeled button Toggle Switch Slide switch oF A oo Push Button LED Button Dialog Button Note The dialog button dialog checkmark and dialog radio button look different on each platform For information about dialog box controls on various platforms see the Customizing Dialog Box Controls section in Chapter 8 Introduction to Front Panel Objects Some Boolean indi
493. r it is equivalent to giving the array an initial value Most languages require you to indicate a maximum size for an array as part of the declaration The information about the size of the array is not treated as an integral part of the array which means you have to keep track of the size yourself In G you do not have to declare a maximum size for arrays because G automatically preserves the size information for the array Furthermore with G you cannot store a value outside the bounds of an array In many conventional programming languages there is no such checking and consequently you inadvertently can corrupt memory Clusters A G cluster is an ordered collection of one or more elements similar to structures in C and other languages Unlike arrays clusters can contain any combination of G data types Although cluster and array elements are both ordered you access cluster elements by unbundling all the elements at once rather than indexing one element at a time Clusters are also different from arrays in that they are of a fixed size As with an array a cluster is either a control or an indicator a cluster cannot contain a mixture of controls and indicators You can use clusters to group related data elements that appear in multiple places on the diagram which reduces wire clutter and the number of connector terminals subVIs need Most clusters on the block diagram have a common wire pattern although clusters of numbers somet
494. r object G 6 National Instruments Corporation front panel function Functions palette G G global variable glyph GPIB graph control H handle Help window hex National Instruments Corporation Glossary The interactive user interface of a VI Modeled from the front panel of physical instruments it is composed of switches slides meters graphs charts gauges LEDs and other controls and indicators Built in execution element comparable to an operator function or statement in a conventional language Palette containing block diagram structures constants communication features and VIs Graphical programming language Non reentrant subVI with local memory that uses an uninitialized shift register to store data from one execution to the next The memory of copies of these subVIs is shared and thus can be used to pass global data between them A small picture or icon General Purpose Interface Bus is the common name for the communications interface system defined in ANSI IEEE Standard 488 1 1987 and ANSI IEEE Standard 488 2 1987 Hewlett Packard the inventor of the bus calls it the HP IB Front panel object that displays data in a Cartesian plane Pointer to a pointer to a block of memory handles reference arrays and strings An array of strings is a handle to a block of memory containing handles to strings Special window that displays the names and locations of the terminals f
495. r the extra cases G Programming Reference Manual 3 14 National Instruments Corporation Chapter 3 Building SubVis Using the Hierarchy Window The Hierarchy window displays a graphical representation of the calling hierarchy for all VIs in memory including type definitions and global variables You can configure many aspects of the display in the Hierarchy window For example you can have the layout displayed horizontally or vertically and you can include or exclude VIs in vi 1ib global variables or type definitions Other useful features of the Hierarchy window include the ability to access the VI Setup Edit Icon Show VI Info and Print Documentation options the ability to drag or copy and paste hierarchy nodes to a block diagram of another VI as a subVI and the ability to search for hierarchy nodes by name Opening the Hierarchy Window You can open the Hierarchy window in any of the following ways e Select Project gt Show VI Hierarchy The Hierarchy window is shown with the VI of the current active window as the focus node e Under the pop up menus of subVIs global variables or type definitions select Show VI Hierarchy The Hierarchy window appears with the selected subVI global variable or type definition as the focus node e Ifthe Hierarchy window is already open you can bring it to the front by selecting it from the list of open windows under the Windows menu The Hierarchy window can be s
496. r to use the function panel names instead you can turn off this option manually and then individually rename the items that have name conflicts Renamed items retain their user supplied names even when the Use C Function Names option is changed Capitalize and Remove Underscores in Names Because names built from C function names tend to be less pretty than those derived from the function panel item names this option attempts to make them prettier by capitalizing initial letters and replacing underscores with spaces Because it cannot expand abbreviations the results still might not be as pleasing as the FP names but this is inevitable if you have duplicate FP item names you do not want to rename individually Convert All Control Names to Lowercase Converts control names to lowercase to conform to VXI Plug amp Play standards Assign Instrument Driver Icon Based on Name Assigns icons to VIs based on the name of the generated VIs The converter searches for keywords such as initialize close self test reset configure or measure in the name of the function and uses the corresponding icon If no keywords are found a default icon is used Additionally the instrument prefix is stamped into the icon at the top left up to a maximum of seven characters Default Size for Array Parameters When an instrument driver DLL outputs an array the memory into which the DLL writes the array must be preallocated and passed into the
497. r waveforms with a varying timebase Both graphs can display any number of plots Each of these graphs can accept several data types This minimizes the extent to which you need to manipulate your data before displaying it These data types are described in the next section Following the section on graph data types are sections describing some of the more advanced options of the graph These include customizing the appearance of the graph displaying and manipulating cursors and displaying a legend for the graph Plotting Single Plot Graphs Waveform Graph Data Types For single plot graphs the waveform graph accepts two data types These data types are described in the following paragraphs The first data type that the waveform graph accepts is a single array of values The graph interprets the data as points and increments them by G Programming Reference Manual 15 2 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators one starting at x 0 The following diagram illustrates how you can create this kind of data ir rray ofy valusascassurmes noD dx 1 The second data type is a cluster of an initial x value a Ax value and an array of y data The following diagram illustrates how you can create this kind of data cluster of xo dx and y XY Graph Data Types The XY graph accepts two data types for a single plot graph These data types are described in the following paragraphs
498. rase 15 25 Chart Update Modes 20 ccscessesseescpsceseces cos jesuseeaseedsveetstescadessgevacbzecenses 15 26 Stacked Versus Overlaid Plots cee ces eeceeceeeseeeeeeseneeseecsecnaesaes 15 28 Intensity Graphs T A E E E ET RE 15 29 Intensity Graph Data Type seesessesessseesessssesreseesrsresrsresreresesrsrerresreresrenrsreeseees 15 29 Intensity Graph Option 3 5sccsc0 scssscesessces aces ses sadsesssseessastesscdecsesbeseedssesessenssseeseeses 15 29 Graph Cursors 1560S ree ces eens hil webiste E EEE EE E Ge E vista E dase 15 30 Intensity Charts oee e Eea E eE n EEE E E E TE Er Rasi 15 36 Intensity Chart Options cece osrin oeer ee ressis n Ero orenk Tris 15 38 GolOr MappiNg sesio sec sccee eseop ieste ssri aTe os riss TEs KERETE ETSE series 15 40 Block Diagram Programming Chapters 16 through 21 Chapter 16 Introduction to the Block Diagram Terminals and Nodes ream a ad E n a ees 16 1 Temm als cess des dock nonnene a ea ee aae a eai a e et dedese ce 16 1 Control and Indicator Terminals cceceeessssesesesesessseeeseseeeeees 16 2 Constants nenten a a N A E teteone eee 16 3 User Defined Constants esesesesseeeeeeeeeesesrsrsesrssrerererererere 16 3 Universal Constants ccccccccccccccsecccccesecesesesessssssnsenseeeseees 16 7 National Instruments Corporation xiij G Programming Reference Manual Table of Contents oo S A E A edie tte Sasa hd Sata ei ieee os 16 8 BUM CHONS sisser esegesi iras vaste
499. rating tool the control toggles to the opposite state In edit mode you can use the Labeling tool to change the text in either state for example YES instead of ON National Instruments Corporation 10 3 G Programming Reference Manual Chapter 10 Boolean Controls and Indicators By default the text is centered on the button If you want to move the text select Release Text from the pop up menu At this point use the Positioning tool to reposition the text or choose the option Lock Text in Center Select the Boolean text then use the Text menu to change the font size and color of the text You also can remove the Boolean text from both states by toggling the Boolean Text option on the Show submenu The Boolean controls that do not appear in the palette as labeled Booleans are unlabeled by default However you can select Boolean Text from the Show submenu to make them labeled You can move the Boolean text in these Booleans Their text is not locked in the center of the button unless you select Lock Text in Center from the pop up menu If you want to change the font of either the name label or the Boolean text without changing both select what you want to change with the Labeling tool and then use the Font ring options to make the changes you want Stopping on a Boolean Value If you want to recognize when a conditional test fails to produce the correct Boolean value select Suspend if True or Suspend if False from the D
500. ration 20 9 G Programming Reference Manual Chapter 20 Attribute Nodes Bounds Attribute Read Only The Bounds Attribute reads the boundary of an object on the front panel in units of pixels The value includes the control and all of its parts including the label legend scale and so on This attribute consists of a cluster of two unsigned long integers The first item in the cluster Width is the width of objects in pixels and the second item in the cluster Height is the height of the object in pixels The Bounds Attribute is a read only attribute It does not resize a control or indicator on the front panel Most objects have other attributes for resizing such as the Plot Area Size attribute for Graphs and Charts This attribute is useful when you need to read the overall size of a control including all optional parts so that you can position other controls in relation to the control with which you are working You can determine the bounds of the digital control as shown in the following illustration Examples of Attributes Specific to Controls or Indicators EE Active Plot Plot Color In the following sections you can learn about common applications of Attribute Nodes See the general directory to explore other uses of the Attribute Node Changing Plot Color on a Chart The attributes shown at left set or read the active plot the trace for which subsequent trace specific attributes are set or read a
501. rations Create Key Navigation Replace Representation Data Range Format amp Precision Import Picture Import Picture After Import Picture Before Remove ltem National Instruments Corporation 13 9 G Programming Reference Manual Chapter 13 List and Ring Controls and Indicators Changing the Size and Text of Text amp Pict Rings You can enlarge the Text amp Pict Ring to make more room for the contents just as you can enlarge all controls You also can decrease the size When you resize the Text amp Pict Ring from one of its bottom corners the height of the text area changes When you resize the Text amp Pict Ring from one of its top corners the height of the picture area changes These resizing capabilities are shown in the following illustration Text amp Pict Ring Text amp Pict Ring Text amp Pict Ring Enumerated Type Controls An enumerated type control is similar to a text ring control If data from an enumerated type is connected to a Case Structure however the case displays the string or text of the item instead of a number The enumerated type data type is unsigned byte unsigned word or unsigned G Programming Reference Manual 13 10 National Instruments Corporation Chapter 13 List and Ring Controls and Indicators long selectable from the Representation palette An example is shown in the following illustration Enumeration Front panel Continuous object Conti
502. ray as in the following illustration index 0 1 2 3 4 5 11l element Melissa Greg Gregg Don Duncan Thad array index continued 6 7 8 9 10 11 element array Dean Stepan Kate Mary Mark continued A simple example of an array is a list of names represented in G as an array of strings as shown in the following illustration Jeff Paul Rob BrucelSteve Meg Jack Brianl Deb Kevir Tom List of Names in an Array of Strings Another example is a waveform represented as a numeric array in which each successive element is the voltage value at successive time intervals as shown in the following illustration index vols 0 4 09 1 4 08 0 1 0 7 0 3 0 3 0 2 Waveform in an Array of Numbers A more complex example is a graph represented as an array of points where each point is a pair of numbers giving the X and Y coordinates as shown in the following illustration G Programming Reference Manual 14 2 National Instruments Corporation Chapter 14 Array and Cluster Controls and Indicators index X coord Y coord Graph in an Array of Points The preceding examples are one dimensional arrays A two dimensional array requires two indices to locate an element a column index and a row index both of which are zero based In this case we speak of an N column by M row array which contains N times M elements as shown in the following illustration column index 01 23
503. re Insert After or Replace to add that option to the list When you select a path G normally searches that directory but not its subdirectories You can make the search hierarchical by appending a as a new path item Some examples on different platforms e Windows To search the directory C VIs recursively you enter C VIs e Macintosh To search recursively the VIs folder on the HD disk you enter HD VIs e UNIX To search recursively usr home gregg vis youenter usr home gregg vis National Instruments Corporation 7 5 G Programming Reference Manual Chapter 7 Customizing Your G Environment You can use the special pull down menu shown in the following illustration which is located to the right of the Browse button to select from several special directories lt vilib gt lt vilib gt lt topwi gt lt topvi gt lt foundyi gt lt foundyvi gt These directories are as follows e lt vilib gt as a path entry is a symbolic path that refers to the vi lib directory inside of the Library Directory e lt topvi gt isasymbolic path that refers to the directory containing the top level VI e lt foundvi gt refers to a list of directories that LabVIEW builds each time a VI is loaded During a search any directory in which LabVIEW finds a subVI or that you manually select is added to this list Use this symbolic path so that if you move or rename a directory of VIs and then open a
504. rence names the search is case sensitive You have the option to enclose the preference value in double or single quotation marks For example to use a default precision of double and use a search path that recursively searches the a particular directory you specify the following preference entries labview defPrecision double labview viSearchPath usr lib labview LabVIEW also searches for preferences in a file named labviewrc in the applications directory For example if you have installed your LabVIEW files in opt labview preferences are read out of both opt labview labviewrc and the labviewrc file in your home directory Entries in the labviewrc file override conflicting entries in the labviewrc file You might want to use this global preference file to store things that are the same to all users such as the VI search path G Programming Reference Manual 7 24 National Instruments Corporation Chapter 7 Customizing Your G Environment You also can specify a preference file on the command line when you start LabVIEW For example to use a file named lvrc instead of labviewrc type labview pref lvrc VW Caution The labviewrc file is still read in this case Also keep in mind that changes made in the Preferences dialog box are written to the 1vrc file in this example Customizing the Controls and Functions Palettes G has a powerful set of tools for customizing the Controls and Functions palettes in any
505. ribes two utilities the Hierarchy window which displays the hierarchy of your VIs and the Find utility which finds occurrences of subVIs as well as other objects or strings of text that you indicate Hierarchical Design One of the keys to creating G applications is understanding and using the hierarchical nature of a VI After you create a VI you can use it as a subVI in the block diagram of a higher level VI Therefore a subVI is analogous to a subroutine in C Just as there is no limit to the number of subroutines you can use in a C program there is no limit to the number of subVIs you can use in a G program You also can call a subVI inside another subVI When creating an application you start at the top level VI and define the inputs and outputs for the application Then you use other VIs as subVIs to perform the necessary operations on the data as it flows through the block diagram If a block diagram has a large number of icons you can group them into a lower level VI to maintain the simplicity of the block diagram This modular approach makes applications easy to debug understand and maintain You can create a subVI from a VI or you can create a subVI from a selection portion of a VI Both methods are described in this chapter Creating SubVIs from Vis The icon of a VI is its graphical symbol The connector of a VI assigns controls and indicators to input and output terminals If you want to call your VI from the b
506. rieval system or translating in whole or in part without the prior written consent of National Instruments Corporation LabVIEW and BridgeVIEW are trademarks of National Instruments Corporation Product and company names listed are trademarks or trade names of their respective companies WARNING REGARDING MEDICAL AND CLINICAL USE OF NATIONAL INSTRUMENTS PRODUCTS National Instruments products are not designed with components and testing intended to ensure a level of reliability suitable for use in treatment and diagnosis of humans Applications of National Instruments products involving medical or clinical treatment can create a potential for accidental injury caused by product failure or by errors on the part of the user or application designer Any use or application of National Instruments products for or involving medical or clinical treatment must be performed by properly trained and qualified medical personnel and all traditional medical safeguards equipment and procedures that are appropriate in the particular situation to prevent serious injury or death should always continue to be used when National Instruments products are being used National Instruments products are NOT intended to be a substitute for any form of established process procedure or equipment used to monitor or safeguard human health and safety in medical or clinical treatment Table of Contents About This Manual Organization of This Manual genrerne a xx
507. ring when creating the drawing commands Applicable for black and white printing printer dithering is a method of adding gray scales to an image instead of only black and white areas This option is not dependent on printer type Windows only Scale printer fonts Enables a more complicated algorithm to select a different font if the first one doesn t scale correctly If all of the text on your printed VI does not appear or if it is too large you can try this option to see if it improves the appearance of the printout This option is not dependent on printer type PostScript printing Directs G to translate the VI print data in PostScript PS format and send it to the printer as PostScript text If G Programming Reference Manual 7 16 National Instruments Corporation Chapter 7 Customizing Your G Environment you have a PostScript printer and a PostScript printer driver the printout is a graphics image Do not select this option if your printer or printer driver does not support PostScript printing or you will have a printout containing nonsense PostScript level 2 Tells G that the connected printer supports PostScript level 2 If this box is checked G sends PostScript level 2 code to the printer If the box is not checked G sends Color Grayscale code Color Grayscale is a subset of PostScript level 2 Select this option only if your printer supports PostScript level 2 Windows UNIX Bitmap printing Directs G to create
508. rinting If you want to print something under the control of your VI rather than interactively as with the Print Window and Print Documentation dialog boxes use programmatic printing With this type of printing you can program your VI to print after every execution You also can program it to print out the contents of a specific front panel or a specific control during execution perhaps in response to the user pressing a Print button Programmatic printing allows you to control when printouts occur as well as the appearance of your printouts such as if or not a header is printed To implement programmatic printing select Operate Print at Completion When this option is on G prints the contents of that front panel any time the VI completes execution If the VI is a subVI G prints when that subVI finishes execution before it returns to the caller Controlling When Printouts Occur In some cases you do not want a VI to print out every time You might want it to occur only if the user presses a button or if some condition occurs such as a test failure You also might want more control over the format for your printout Or you might want to print only a subset of the controls or even just one specific control You can create a subVI whose panel is formatted the way you want the VI to look Instead of selecting Operate Print at Completion on your VI select it from the subVI When you want a printout you can call the subVI p
509. rmat you can display the elements in a cluster on the front panel and process them in an array To do this use the Array To Cluster and Cluster To Array functions discussed in the Online Reference Function and VI Reference Cluster Functions topic Operating Arrays You operate the element of the array exactly as if it were not part of the array You operate the index display the same way you operate a digital control To set the value of an array control element bring the element into view with the index display then set the value of the element Default Sizes and Values of Arrays You cannot fix the size of a G array However when you set the default values of an array control you also set the default size Do not make the default size larger than necessary Keep in mind that if you set an array National Instruments Corporation 14 11 G Programming Reference Manual Chapter 14 Array and Cluster Controls and Indicators to have a large default value all of the default data is saved along with the VI thus increasing the size of your file A new array shell without an element is undefined It has no data type and no elements and it cannot be used in a program After you assign an element to the array it is an empty array its length is 0 Although it also has no defined elements you still can use it in the VI The array control dims all elements indicating they are undefined The following illustrations show an array control in
510. rminals for accessing data from the datalog file If yourun the calling diagram the subVI does not execute Instead you retrieve data from a specified record of the datalog file It also returns the time that the data was logged and a National Instruments Corporation 4 7 G Programming Reference Manual Chapter 4 Executing and Debugging VIs and SubVIs Boolean value indicating whether the indicated record number is invalid Description Show Terminals Replace Cluster Tools Relink To Subtil Open Front Panel Subli Node Setup Enable Database Access The following illustration shows the halo terminals for accessing the logged data invalid record record 7 cluster of front panel data in panel order Celuster of uae for secs since LY reference time ul for additional mzecs G Programming Reference Manual 4 8 National Instruments Corporation Chapter 4 Executing and Debugging Vis and SubVIs If the subVI has n logged records you can wire any number from n to n 1 to the record terminal You can access records relative to the first logged record using non negative record numbers 0 means first record means second record and so on through n 1 which stands for the last record You can access records relative to the last logged record using negative record numbers 1 means last record 2 means second to the last and so on through n which means the first record If you w
511. rn e Ei o E REE e a EAEE sues EEEE EE EREET EEE ER 2 1 Tools Palette noson i a eaeoe eeen E Eee aa OE EE 2 4 UGA NiE E E sss ish EE S TT 2 6 Pop Up Menus erin ek oeron eek deste EE S REESE KENE eee 2 6 Editing VIS e e N A A REE O E eG Aeteets 2 7 Selecting ODJectS csee ioeie eiee eara EE EEE EEES E EKA Sees OERE 2 7 Dragging and Dropping VIs Pictures and Text in G essseesseeeesererreseeereeee 2 8 Positioning ODJects re ereer ana E EE E pene a a bees 2 9 Alh nina Objects roire erena a E EEEE SETETE 2 11 Distributing ODJeCts sasies irio teese een ee a a e 2 12 Duplicating Objects si secs ssssescesscessstassstes iss sibses hasas ipi ESE EE k pets ssteeandenes 2 12 Deleting Objects sce sscisse eo reee non e e e ea e KE a e 2 13 Labeling ODjeCts anren ie e e nr a E E EEE 2 14 Pree Labels oro rne oaoa Ee E eE a EEA E ates AES 2 14 Text Characteristics ns siisi cien si reae sorpts aaae r p onoare EERTE sro i oas 2 16 Resizing OHJEISTA E E ERER 2 23 Labels na e R tts E E E E R 2 23 Front Panel and Block Diagram Work Space eseeeseeeeseeereseeeee 2 24 Coloring OBjECtS iiss oein ionerne sestas aeip rin a Ean pE EE EIRE isho sesseesasoueesceeees 2 24 Creating Object Descriptions esessseeeessseeesssrseerrseterstsseerssrsrertsreerssrereesreersrent 2 26 Creating VI Descriptioms cssekiscesssestisseceessescsasbistes E Erei p E ESEE Eaei 2 27 SENAT nt AAVA EAEE E T E 2 27 Indivadtnal VI Files ssc sssssctssceesisetisstesssesssveasees aa
512. rol and that you subsequently use that type definition in many different VIs Later you change the type definition to a 16 bit integer digital control When you change the type definition you can update every VI that uses that type definition automatically or if you prefer you can check if the type definition in a VI needs to be updated You also can make a type definition that is a cluster such as a cluster of two integers and a string If you change that type definition to a cluster of two integers and two strings you can update the type definition everywhere it is used As long as the data type matches the master copy a type definition can have a different name description default value size color or even a different style of control for example a knob instead of a slide Strict Type Definition Everything Must Match A type definition also can force almost everything about the control to be identical everywhere it is used not just its data type but also its size color and appearance This is called a strict type definition National Instruments Corporation 22 19 G Programming Reference Manual Chapter 22 Custom Controls and Type Definitions The only aspects of a control that can be different from the master copy of a strict type definition is the name description and default value As an example suppose you make a strict type definition that is a double precision digital control with a red frame Like the general
513. rol showing True or hidden False Visible Format amp Precision temp Gq Cluster of numeric format and precision Numeric format 0 Decimal 1 Scientific 2 Engineering 3 Binary 4 Octal 5 Hexadecimal 6 Relative Time Number of digits after the decimal point Online Reference In addition to the Help window G has more extensive online information available To access this information select Help Online Reference For most block diagram objects you can select Online Reference from the pop up menu of the object to access its online description You also can access this information by pressing the button shown to the left which is located at the bottom of the Help window Creating Your Own Help Files You can create your own online help or reference documents if you have the right development tools Help documents are based on formatted text documents You can enter topics in these documents that create connections to your VIs The source files for all platforms must be in Windows Help format It is possible to create help documents for multiple platforms National Instruments Corporation 1 9 G Programming Reference Manual Chapter 1 Introduction to G Programming When you have created source documents you use a help compiler to create a help document If you want help files on multiple platforms you must use the help compiler for the specific platform o
514. rols as parts You cannot open a second Control Editor window for the main control already being customized The following illustration shows the Control Editor for the slide on the left and a Control Editor window for the digital display on the right You do not have to be in customize mode to open a nested Control Editor window unless you are unable to select the control part in edit mode G Programming Reference Manual 22 16 National Instruments Corporation Chapter 22 Custom Controls and Type Definitions Untitled 1 File Edit Oper Morne a File Edit Operate Project Windows Help E Control z Ept System Font z Eok d E 10 0 f ao BO 6 0 4 0 2 0 00 4 Adding Cosmetic Parts to Custom Controls When you are making a custom control in the Control Editor you can make even more changes to its appearance by adding cosmetic or text parts to it If you paste a picture or text from the Clipboard create a label with the Labeling tool or select a picture from Controls Decorations that picture or text becomes a part of your control and appears with the control when you place it on a front panel You can do this in either edit or customize mode in the Control Editor You can move resize or change the layering order of the new part just like any other part Your addition appears as a decoration part in the Control Parts window in customize mode You also can del
515. rray of clusters where each cluster contains the gain lower limit upper limit and the channel name As described in the previous section this data structure is difficult to manipulate efficiently because you generally have to go through several levels of indexing and unbundling to access your data Also because the data structure is a conglomeration of several pieces of information you cannot use the Search 1D Array function to search for a channel You can use Search 1D Array to search for a specific cluster in an array of clusters but you cannot use it to search for elements that match on a single cluster element Alternative Implementation 1 As with the previous example you could choose to keep the data in two separate arrays One could contain the channel names The other array can contain the channel data The index of a given channel name in the array of names is used to find the corresponding channel data in the other array Notice that because the array of strings is separate from the data you can use the search 1D Array function to search for a channel In practice if you are creating an array of 1 000 channels using the Change Channel Info VI this implementation is roughly twice as fast as the previous version This change is not very significant because there is other overhead that is affecting performance If you have read through the Memory Usage section of this chapter you might have seen a note indicating that yo
516. rs your text and moves the cursor into the cell below The lt Enter gt key on the numeric keypad enters your data and terminates the entry Pressing the lt Shift gt key while pressing the arrow keys moves the entry cursor through the cells You can select individual cells with the Operating tool or by double clicking and you can extend the selection by pressing lt Shift click gt and then dragging Moving outside the current contents of the table scrolls the table while extending the selection A border appears around selected cells to National Instruments Corporation 11 7 G Programming Reference Manual Chapter 11 String Controls and Indicators indicate that they have been selected You can turn scrolling on or off using the Selection Scrolling option in the table pop up menu You also can select all the data in a table or all the data in a row or column Position the Operating tool at the upper left corner of the table to select all data A special double arrow cursor appears when the tool is positioned properly as shown in the following illustration Click on the area to select the data oep D To select an entire row or column of data position the Operating tool at the left border of a row or at the top of a column Again a special arrow cursor appears when the tool is properly positioned shown in the illustration that follows Click on and drag across width of column or height of row to select the data
517. rsrerrsreee 8 10 Chapter 9 Numeric Controls and Indicators Digital Controls and Indicators eee eee eeeeseeseecseceecsecaeaeceeceseeeeeeseeeeseaeeeeseaeeeeeeas 9 2 Digital Numeric Options 00 00 eee areis e E eire r eener EE es erei r 9 3 Displaying Integers in Other Radixes eeeseeesseresrsesersrrsrrresrrersrees 9 4 Changing the Representation of Numeric Values 0 0 0 0 9 4 Range Options of Numeric Controls and Indicators 00 0 eeeseeceeceseeees 9 6 Numeric Range Checking eee ceecssessecseeseceeeeseeeeeeseeeeseseeeesenes 9 7 Format and Precision of Digital Displays 00 eee ee ceseeeeceseeeeeeeeeeeeeneeeeeene 9 9 Slide Numeric Controls and Indicators cece ceeeeeeseeeeecseesseceeceseeeeceseeeeeeseeeeseneeeeeens 9 12 Slide Scales cies eda en a iea tiie E E boii ain 9 14 Sale Markers ca a E T EEO EE 9 15 Changing Scale Limits 00 0 0 eee eeeeeeeecsecreesaeceesseesees 9 16 Selecting Non Uniform Scale Marker Distribution 9 16 TERES Cale rrp e ireen eats E E E native sie et aath eked 9 18 Filled and Multivalued Slides 0 0 ceeieeeeccesceseeesecseeceecseaececeseceeeeseeeeeeees 9 20 Rotary Numeric Controls and Indicators cece eee eseeecseeeseceeceeeeceeeeeeeeeeeseaeeeeeens 9 21 Color BOX sieaa dd ais E ae dentist pevtenias Basen Ata Seiad eee 9 24 Color 1 ne en 9 25 Unit Types nne E E o shld E E E E EE ES 9 26 Entering Units ons oira ea eas a ea ee Goh esas AES 9 31 Units and Strict Type Checking 0 e
518. rt update mode 15 27 update modes 15 26 to 15 28 While Loops auto indexing number of iterations 18 9 overview 18 7 to 18 8 running out of memory note 18 9 avoiding cycles in subVIs 3 12 National Instruments Corporation l 57 Index avoiding unnecessary computations 26 9 to 26 11 icon for 18 2 18 4 placing objects inside structures 18 4 to 18 5 purpose and use 16 11 18 4 questions about B 13 shift registers 18 10 to 18 13 terminals inside loops 18 6 to 18 7 window options VI Setup dialog box 6 4 to 6 6 Allow Run Time Pop Up Menu 6 5 Allow User to Close Window 6 5 Auto Center 6 5 Dialog Box option 6 5 Enable Log Print at Completion 6 6 Hilite lt Return gt Boolean 6 5 illustration 6 5 Show Toolbar 6 6 Size to Screen 6 5 Windows menu Show Diagram 1 3 2 4 Show Error List 4 10 Show History 25 6 Show Parts Window 22 7 Show VI Info 2 27 wires bends 17 6 branches 17 6 dots at wire junctions showing 7 11 junctions 17 6 overview 1 5 segments 17 6 wiring block diagrams 17 1 to 17 17 basic wiring techniques 17 1 to 17 5 complicated VIs 17 4 to 17 5 deleting wires 17 6 to 17 10 mouse symbol for Wiring tool 17 1 moving wires 17 6 to 17 10 off screen areas 17 10 to 17 11 G Programming Reference Manual Index selecting wires 17 6 to 17 10 situations to avoid 17 15 to 17 17 hidden wire segments 17 16 wire loops 17 15 wiring underneath objects
519. ry physical or virtual that is large enough for the string or array a dialog box appears to indicate that it was not able to allocate the required memory If you want to save changes to your VIs after G runs out of memory you might save your VIs to another location or make sure that you have a backup copy After you restart G with more memory you can load these VIs into memory check to see that the save was successful and proceed in your VI development Windows What do I do if LabVIEW or BridgeVIEW crashes when printing This crash might be related to the video driver See the question below concerning random crashes on Windows for information on how to proceed While running LabVIEW or BridgeVIEW what should do if receive a failure message which includes a source code file and line number This indicates that an error has occurred and the application cannot proceed Please notify National Instruments of this message and explain what action triggered the message G Programming Reference Manual B 4 National Instruments Corporation Appendix B Common Questions about G Windows What should I do if LabVIEW or BridgeVIEW tends to crash randomly The crashes might be general protection faults or failure messages which include a source code file and line number Often random crashes involve problems with the video driver on the machine To establish if this is the case use standard VGA as the video driver To change vide
520. s 00 eee eee eeeeeeeneeeeeeeee 26 32 Obvious Implementation eee cee ceeeeeceeeeeceeeeseeeeeeeeeeseseeeaeenes 26 33 Alternative Implementation 1 cece cee ceseeeeceseeeeeeeeteeeeeeeeeeees 26 33 Alternative Implementation 2 0 cece cseceseeeeceseeeseeeeeeeseneeeeeens 26 33 Case Study 3 A Static Global Table of Strings eee cece eeeeeeeeeeeeeeene 26 35 G Programming Reference Manual xviii National Instruments Corporation Table of Contents Chapter 27 Portability Issues Portable and Nonportable VIS ccssesseesseesseceececeeecsaceeececeeeeeaeceseecaeeeaeeceeeecseeeeaeens 27 1 Porting between Platforms norrena a a hs ietesnd ces ath sabteaeosaseb ea a E 27 2 Separator Character Differences eee eecseessececeseeseceseeseceeeeeeseeeeeeseneeaes 27 2 Resolution and Font Differences 0000 0 eee eeeeeeeeeeeeceeeesecaeceaecneceseeseeneeeeenes 27 2 Overlapping Labels sisne eris i e EE EEES E E dunes 27 4 Picture Ditferences msinione o ee Aes i E A ee i ee 27 4 Appendix A Data Storage Formats Data Formats for Front Panel Controls and Indicators cccceseccceeesssseeeecesssneeeeceees A 1 181079 ar 1 Sear E E A EE E E E E E A 1 Nita TTE TOE A E E E E E E EE E EE A 1 1 1 010 2 6 EEA A A E E ree ee EE EAEE A 1 TOU E EEE EEE EEE SEE AE SE AE EAE ETE E EN A 2 Singler Bi cette SRA attain Sn aia nee oni a A 2 Long Integers eniascet aner hess pesaseases vabesbbarebasseptanes esse esvep Eii A 3 Wordnte Bet sceoi
521. s if you want to return different values to the calling VI In fact the suspend mode is the only time you can set values on indicators Click on the Run button again when you are ready to return the indicator values of the subVI to the calling VI If you want to go back to the beginning of the VI click on the Skip to Beginning button Skip to Beginning The Return to Caller button appears when a suspended subVI is idle Click on it to return to the caller VI Notice that you can return to a Return to Caller caller without executing the current VI If you want to execute it be sure to press the Run button before returning to the caller Viewing Hierarchy Windows During Suspension The Hierarchy window displays an exclamation point glyph to indicate a subVI that has been suspended The following illustration shows a subVI in the Hierarchy window with the Suspend when Called option is on G Programming Reference Manual 4 30 National Instruments Corporation Chapter 4 Executing and Debugging Vis and SubVIs Disabling Debugging Features To reduce memory requirements and to increase performance slightly you can compile a VI without various debugging features To do this go to VI Setup Window Options from the connector pane pop up menu on the front panel and deselect the checkboxes for Show Run Button Show Continuous Run Button Show Abort Button or Allow Debugging Commenting out Sections of Diagrams In some cases you might
522. s a copy of the picture of the part on the Clipboard If you select Copy to Clipboard for the slide housing the Clipboard contains a picture of a tall narrow inset rectangle This Clipboard picture can be pasted onto any front panel or imported as the picture for another part using Import Picture These pictures are just like the Decorations in the Controls palette When you need simple shapes like the housing rectangle for other parts there are several advantages to using pictures copied from other parts instead of making them in a paint program Pictures taken from existing parts or decorations look better than pictures made in a paint program when you change their size For example a rectangle drawn in a paint program can only grow uniformly enlarging its area but also making its border thicker A rectangle copied from a part like the slide housing keeps the same thin border when resized Another advantage is that built in parts appear basically the same on both color and black and white monitors In addition you can color pictures taken from parts or decorations with the Color tool Pictures imported from another source keep the colors they had when they were imported because those colors are a part of the definition of that picture Import Picture Replaces the current picture of a cosmetic part with the picture that is currently on the Clipboard Use this option to individually customize the appearance of your controls For examp
523. s and warnings for other VIs by selecting the name of the VI from the VI List pop up menu The following list contains some of the most common reasons for a VI being broken during editing e A function terminal requiring an input is unwired For example you must wire all inputs to arithmetic functions You cannot leave unwired functions on the diagram while you run the VI to try out different designs e The block diagram contains a broken wire because of a mismatch of data types or a loose unconnected end You can remove broken wires including wire stubs you cannot see with the Edit gt Remove Bad Wires command or by typing lt Control B gt e A subVI is broken or you edited its connector after you placed its icon in the diagram e You might have a problem with an object you have made invisible disabled or otherwise altered through an Attribute Node Restore the object using the Attribute Node to fix the problem if possible Interpreting Error Messages The following list contains some possible errors in a form similar to the way they look in the Error List window Table 4 1 Error Messages Error Messages Descriptions Function Name contains unwired A required input is not wired or the type is or bad terminal inappropriate Wire the required inputs with the proper data types Code Interface Node object cod You did not link the object code of a CIN properly not loaded Pop up on the node
524. s chapter for more information Saving Custom Controls If you want to use your custom control on other front panels choose File Save as from the main menu of the Control Editor You save a control the same way you save a VI in a directory or in a VI library A directory or VI library contains controls VIs or both If you close the Control Editor window without saving your changes to the control a dialog box asks you if you want to save the control Using Custom Controls When you save the custom control you can use it on other front panels by selecting the Controls Select a Control from the front panel of any VI For more information about adding a custom control to the Controls palette see the Customizing the Controls and Functions Palettes section of Chapter 7 Customizing Your G Environment G Programming Reference Manual 22 4 National Instruments Corporation Making Icons control icon Chapter 22 Custom Controls and Type Definitions If you save your controls so that they appear in the Controls palette you should make an icon representing the control before you save it Pop up or double click on the icon square in the top right corner of the Control Editor window to create an icon for the control This icon represents the control in the palette when you save the control in a library directory Independent Instances of Custom Controls You can open any custom control you have saved by selecting File Op
525. s drawn on the same grid An example of overlaid plots is shown in the following illustration You can display multiple plots alternatively by stacking one above the other with a different Y scale for each plot by selecting the Stack Plots option from the chart pop up menu If you do this the Y scale for each G Programming Reference Manual 15 28 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators chart can have a different range An example of stacked plots is shown in the following illustration When you input data to the chart as a cluster the chart automatically stacks the correct number of plot displays When you input data as a 2 D array you must create the correct number of plot displays using the Legend available in the Show submenu of the pop up menu As you enlarge the Legend display to increase the number of plots the number of stacked plot displays increases to match Intensity Graphs The intensity graph is essentially the same as the intensity chart except it does not retain previous data Each time it is passed new data the new data replaces old data as it arrives For an example of an intensity graph see general examples graphs intgraph 1llb Intensity Graph Data Type The intensity graph accepts two dimensional arrays of numbers where each number is mapped by the chart to a color Rows of the data you pass in are displayed as new columns on the chart If you
526. s never load two VIs with the same name regardless of the paths to those VIs This includes subVIs When you select Replace on a subVI to replace it with a VI of the same name G realizes it already has a copy of the VI in memory and replaces the VI with itself To load the new copy of the subVI you must first remove the old copy from memory The VIs currently are listed in the Windows menu The easiest way to remove the subVI from memory is to close the subVI and any other VIs that call the subVI Open the new copy of the subVI into memory check File Show VI Info to confirm that this is the version you want and then re open the main VI When the VI tries to link to the subVI it finds a copy in memory the new version and uses it rather than search for the previous version The solution to many of these problems is always to give subVIs unique names Loading two Vis that call two distinct subVls with the same name causes problems For example mainl vi and main2 vi both call distinct subVIs which are both named subVI vi l mainl vi is loaded into memory subVI vi is loaded in because it is called by mainl vi 2 main2 vi is loaded into memory linker information signals LabVIEW or Bridge VIEW to load subVI vi The application recognizes that it already has subVI vi loaded into memory tries National Instruments Corporation B 11 G Programming Reference Manual Appendix B Common Questions about G to link main
527. s on the minimum maximum and average number of byes and blocks used by each VI per run See the Performance Profiling section at the beginning of this chapter for more details As shown in the following illustration you can use Windows Show VI Info to have a breakdown of the memory usage for a given VI The left column of this information summarizes disk usage and the right column summarizes how much RAM currently is being used for various components of the VI Notice that these statistics do not include memory usage of subVIs Memory Usage Resources Front Panel 5 4K Block Diagram 11 7K Code Data Total National Instruments Corporation 26 17 G Programming Reference Manual Chapter 26 Performance Issues A fourth method for determining memory usage is to use a VI called the Memory Monitor VI in memmon 11b inside of the general directory This VI uses CINs to determine memory usage for all VIs in memory Rules for Better Memory Usage The main point of the previous discussion is that the compiler attempts to reuse memory intelligently The rules for when the compiler can reuse memory and when it cannot are fairly complex and are discussed at the end of this chapter In practice the following rules can help you to create VIs that use memory efficiently G Programming Reference Manual Breaking a VI into subVIs generally does not hurt your memory usage In fact in many cases memory usage improves b
528. s shown in the following illustration L Point Style i Color lisible Name Bring into View Goto Cursor G Programming Reference Manual 15 34 National Instruments Corporation Chapter 15 Graph and Chart Controls and Indicators Select the Visible Name option from this menu to make the cursor name visible on the plot as shown in the following illustration Selecting Bring into View moves the cursor back into the displayed region of the graph This is helpful when the cursor has moved out of visible range Selecting this option changes the x y coordinate position of the cursor Selecting Goto Cursor moves the displayed region of the graph so that the cursor is visible The cursor position remains constant but the scales change to include the cursor selected The size of the displayed region also stays constant This feature is helpful when the cursor is used to identify a point of interest in the graph such as a minimum or a maximum and you want to see that point You can use the last button for each cursor to lock a cursor onto a a particular plot By clicking on the lock button you see a pop up menu that you can use to lock the cursor to a specific plot If you lock the cursor onto a plot the button changes to a closed lock This pop up menu is shown in the following illustration unlocked locked National Instruments Corporation 15 35 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Ind
529. s the platform and the data for the VI are loaded into memory If the VI needs to be recompiled because of a change in platform or a change in the interface to a subVI then the diagram is loaded into memory as well You also can load the code and data space of subVIs into memory Under certain circumstances you can load the front panel of some subVIs into memory as well This can occur for example if the subVI National Instruments Corporation 26 13 G Programming Reference Manual Chapter 26 Performance Issues uses Attribute Nodes because Attribute Nodes manipulate state information for front panel controls More information on subVIs and their panels is discussed later in this chapter An important point in the organization of VI components is that you generally do not use too much memory when you convert a section of your VI into a subVI If you create a single huge VI with no subVIs you end up with the front panel code and data for that top level VI in memory However if you break the VI into subVIs the code for the top level VI is smaller and the code and data of the subVIs reside in memory In some cases you actually might see lower run time memory usage This idea is discussed later in this chapter in the section Monitoring Memory Usage You also might find that massive VIs take longer to edit You do not see this problem as much if you break your VI into subVIs because the editor can handle smaller VIs more efficien
530. s to options in the Block Diagram Preferences dialog box take effect immediately Debugging Preferences The Debugging Preferences dialog box is shown in the following illustration Preferences Debugging Show data bubbles during execution highlighting Auto probe during execution highlighting C Show warnings in error box by default i PNAS gee pbeesi rt eeitonete pisyies este wed VVCRPP GARASA GHGs LIE ghe The options in this dialog box are as follows Show data bubbles during execution highlighting Animates execution flow by drawing bubbles along the wires You might want to turn this feature off if it significantly slows down performance on your computer Auto probe during execution highlighting Probes scalar values automatically drawing their values on the diagram You can turn off this feature if you find that it clutters the display Show warnings in error box by default Displays warnings in addition to errors in the Error List dialog box A warning does not mean that the VI is incorrect it just points out a potential problem in your block diagram Warn about objects unavailable in the student edition If you have selected the previous option about warnings this option includes warnings about objects unavailable in the LabVIEW Student Edition G Programming Reference Manual 7 12 National Instruments Corporation Chapter 7 Customizing Your G Environment Note Changes to options in the Debugging Pre
531. s to the Call Library Function This is necessary when calling DLLs created with some third party compilers such as Borland C On by default Add Instrument Error I O Checking Causes the converter to drop error handling code on the block diagram of each VI created If you select this option Error In and Out clusters are dropped on the front panel positioned below all other controls and indicators derived from the LabWindows CVI function panel The front panel terminals and Call Library Function on the block diagram are enclosed in a case structure which is executed only if the status field of Error In is FALSE indicating no error On by default Use SubVI for CVI Error Conversion Drops a subVI on the block diagram of each VI to map LabWindows CVI style error codes to G style error clusters suitable for feeding to the General Error Handler The integer return value from the Call Library Function node the Error In cluster and the name of the current VI is passed to the subVI If an error is detected by the subVI it is passed to Error Out with status set to TRUE If a warning is detected it is passed to Error Out but with status set to FALSE Otherwise Error In is passed to Error Out If this option is not set no subVI is dropped and the block diagram is constructed so that an error is indicated in Error Out only if the Call Library Function return value is less than zero On by default Include CVI Class Names in VI Names Aut
532. s vj C Dialog Box Show Scroll Bars fl Window has Title Bar Show Menu Bar i Allow User to Close window Show Toolbar i Allow User to Resize window Show Run Button fl Allow Run Time Pop up Menu El Show Continous Run Button fiilite Return Boolean Show Abort Button Size to Screen Allow Debugging Compile in debugging code M aute Center EJ Enable Log Print at Completion C ean Dialog Box prevents the user from interacting with other windows while this option window is open just as a system dialog box does If you turn off the Allow User to Close Window checkbox in the VI Setup dialog box the Window Options dialog box hides the close box for the VI front panel and dims the File Close option With this VI setup option you can ensure that a user cannot close a run time or pop up VI front panel inadvertently Allow Run Time Pop Up Menu determines if objects on this front panel can display a pop up menu of data operations in run mode When you select the Hilite lt Return gt Boolean option G highlights any Boolean currently associated with the lt Ent er gt Windows and HP UX or lt Return gt Macintosh and Sun key You associate keys with controls using the Key Navigation dialog box which is described in the Key Navigation Option for Controls section of Chapter 8 Introduction to Front Panel Objects The Size to Screen option automaticall
533. se data log you have been viewing Selecting Operate Clear Log File Binding disassociates the VI from any associated log file The next time you log from the front panel data of the VI you will be prompted to specify the log file To view logged data interactively select the Operate Retrieve option The toolbar becomes the data retrieval toolbar as shown in the following illustration E 0 5 8 21 95 17 11 52 000 G Programming Reference Manual 4 6 National Instruments Corporation Chapter 4 Executing and Debugging Vis and SubVIs The highlighted number indicates which record currently is selected for viewing The numbers in square brackets indicate the range of records logged The date and time indicate when the selected record was logged You can view the next or previous record by clicking on the up arrow or down arrow respectively You also can use the up or down arrows on your keyboard Retrieving Data Programmatically You can retrieve data logged from a VI by using the Enable Database Access option or using standard file I O functions to read the file as a datalog file Accessing Databases You also can retrieve data by using the Enable Database Access option You can access this option from the pop up menu of a subVI that has logged front panel data in the associated datalog file of the VI as shown in the following illustration A halo that looks like a file cabinet appears around the datalog file This halo has te
534. searches the remaining string for the numeric pattern If the pattern is found offset is not 1 this diagram uses Build Array to add the number to a resulting array of numbers When there are no values left in the string Match Pattern returns 1 and this diagram completes execution nitialize Array One problem with this diagram is that it uses Build Array in the loop to concatenate the new value to the previous value Instead you can use auto indexing to accumulate values on the edge of the loop Notice that National Instruments Corporation 26 27 G Programming Reference Manual Chapter 26 Performance Issues you end up seeing an extra unwanted value in the array from the last iteration of the loop where Match Pattern fails to find a match A solution is to use array subset to remove the extra unwanted value This is shown in the following illustration Remove last value 1 implied no value encountered From Decimal String to search The other problem with this diagram is that you create an unnecessary copy of the remaining string every time through the loop Match Pattern has an input you can use to indicate where to start searching If you remember the offset from the previous iteration you can use this number to indicate where to start searching on the next iteration This technique is shown in the following illustration Remove last value 1 implied no value encountered string Match Pattern i
535. see your Windows or Macintosh system manual Positioning Objects You can position an object by clicking on it with the Positioning tool and then dragging it to the location you want If you hold down the lt Shift gt key and then drag an object the action restricts the direction of movement horizontally or vertically depending on which direction you first move the object You can move selected objects in small precise increments by pressing the appropriate arrow key on the keyboard once for each pixel you want the objects to move Hold down an arrow key to repeat the action Hold down the lt Shift gt key along with an arrow key to move the object more rapidly National Instruments Corporation 2 9 G Programming Reference Manual Chapter 2 Building Vis If you change your mind about moving an object while you are dragging continue to drag until the cursor is outside all open windows and the dotted outline disappears then release the mouse button This cancels the move operation and the object remains where it was If your screen is cluttered the menu bar is a convenient and safe place to release the mouse button when you want to cancel a move You also can place objects on top of other objects There are several commands in the Edit menu to move them relative to each other For example assume you have three objects stacked on top of each other Object is on the bottom of the stack and object 3 is on top Move To Front
536. seis eee ee er ee A o raas S E sees es EEEE ees 6 2 Execution Opthos srini t isre sec coeesh jes sbes Spucessdes ses SEs senaseeets Esseni ERSTER oS SEES 6 2 Documentation Options e ssseeeeseeeessseesestsstsresteresteetsteetertserenrtsteseeesrentereneers 6 3 Window OpHODS oieri er a E E e E R E E E Ta ii 6 4 SubVI Node Setup Dialog Box eee eseeseecsseesecsecsseeseceseesecesceeeeeeeeeseaeeseeeaecaeeeaes 6 6 Chapter 7 Customizing Your G Environment Setting G Preferences vs in r ee tla eae oats oj Sia eee Bie 7 1 Preferences Dialog Box Options 0 eee cee ceseesecneceseeeeceseeeeeeeeeeeseaeeeeseneeaes 7 1 Path Preferences ynni a a T E AR 7 2 Library Temporary and Default Directories 7 3 VMI Search Path rnnr iere o R EE RE 7 5 Performance and Disk Preferences ccceesccesceceeeeesteeeeeeeseeeeneeeseees 7 6 Front Panel Preferencesinenisocceiiiennnna e i a E 7 9 Block Diagram Preferences eeeessseecceceeceeseceeeeceeceseeceeeeeeeeeneees 7 11 Debugging Preferences 0 seceececeseeesseeeceeceeceenecesceceaeceseeceneeceeeeneens 7 12 Color PretereniCes rasene einet a ae ERRET R 7 13 Font Preferences iii ii iccssezsceeiscsneceeedcavegsencteneeavccootae E ETES 7 14 Printing Preferences cisiveue edie nae eset E S EEEE 7 16 History Preferentes nonen te a E A E 7 17 Time and Date Preferente Sirenene ne i e ia 7 21 Miscellaneous Preferences s neseseeesseseeseseeseseeseserseresesseereersresressesse 7 22 H
537. sest enumeration item If you connect an enumeration control to a numeric value the value is the enumerated type index To wire an enumeration control to an enumeration indicator the enumeration items must match exactly G Programming Reference Manual 13 12 National Instruments Corporation Chapter Array and Cluster Controls and Indicators This chapter describes how to use arrays and clusters You access arrays and clusters from the Controls Array amp Cluster palette shown in the following illustration d d HR aoe H A l Rina 20 O Array amp Cluster See the examples in general examples general arrays 11b The Online Reference Function and VI Reference describes G functions many of which can operate on arrays in addition to scalars The Array Functions and the Cluster Functions topics describe the functions designed exclusively for array and cluster operations Arrays An array is a variable sized collection of data elements that are all the same type as opposed to a cluster which is a fixed sized collection of data elements of mixed types Array elements are ordered and you access an individual array element by indexing the array The index is National Instruments Corporation 14 1 G Programming Reference Manual Chapter 14 Array and Cluster Controls and Indicators zero based which means it is in the range of zero to n 1 where n is the number of elements in the ar
538. several options for customizing the look and behavior of the VI Use the ring at the top of the dialog box to select from three different option categories Execution Options Window Options and Documentation VI Setup Options Execution Options Initially the VI Setup dialog box presents you with execution options for the current VI The Execution Options are shown in the following illustration Ul Setup Execution Options vj LJ Show Front Panel when Loaded CJ Print Panel when V1 Completes Execution LJ Show Front Panel When Called J Print Header name date page FST war a Ee Scale to Fit C Run when Opened E surround Panel with Border Suspend When Called C Reentrant Execution Priority O Low Priority vj Ca Can If you want a subVI panel to open as soon as the top level VI is loaded turn on the Show Front Panel When Loaded option Two of the most useful options of this page are Show Front Panel When Called and Close Afterwards if Originally Closed If you turn these options on for a subVI that sub VI front panel opens automatically when the subVI is called and then closes automatically if it was originally closed The Run When Opened option is another useful option you can use to set up a VI to start running automatically when it opens Setting the Suspend When Called option is the same as selecting Operate Suspend when Called This debuggi
539. show VI info text or history information or components of objects such as the label or description The following options are available for indicating the search string G Programming Reference Manual Match Case Finds only text strings that exactly match the case uppercase or lowercase of the characters you type in Match Whole Word Finds text strings only if they are preceded and followed by a non alphanumeric character such as a space or a plus sign or the start or end of a line If this option is not selected the command matches any string regardless of if it is a fragment of a larger string or not Regular Expression Handles the character string as a regular expression The regular expression has the same specifications the Match Pattern function see Online Help Function and VI Reference for those specifications 3 26 National Instruments Corporation Chapter 3 Building SubVis Text Search Options The More Options button invokes the Text Search Options dialog box which has options for configuring the scope of the text search for each VI Text Search Options Search in V s eau ee E Front Panel E Get Info text o EJ Block Diagram EJ History text Cancel Search in Object s Label Search in Object s Data amp Parts EX Visible labels x Visible EJ Description E Hidden labels EX Hidden The options indicate if and where to search text that is visible or hidden The options are as
540. single element form that is wired to an array indicator in tabular form with five elements displayed The first figure shows that both arrays are empty element values are undefined 1D Array Control 1D Array Indicator 1D Array Control 1D Array Indicator Ext ext If you set the index display of the array control to 9 and set the element value at index 9 to 5 4 the data in the array expands to 10 elements 0 to 9 The value of element 9 is the value you set 5 4 in this example G assigns to the other elements the default value of the digital control 0 00 After running the VI the indicator displays the same values 1D Array Control 1D Array Indicator Ep Selecting Reinitialize to Default for an element resets that element only to its default value Now assume you change the default value of a numeric element from 0 0 to 1 0 You can do this by changing the value in the indicator with the Operating tool and then popping up on the element and selecting Make Current Value Default Or you can choose the Data Range option from the pop up menu Assume you also set the value of element 12 to 7 0 The array now has 13 elements The values of the first 10 elements do not change but elements 10 and 11 have the new default G Programming Reference Manual 14 12 National Instruments Corporation Chapter 14 Array and Cluster Controls and Indicators value of 1 0 and element 12 has the assigned value of 7 0 This example
541. sion PLOCeSS ites atrora ne reee r EE EEEE EEE EES 23 8 Chapter 24 Understanding the G Execution System MUN ta SKINS 2 353 onenig a T RR E NE A ER 24 1 Coop A O isi ie he Res en RO Es hl AA RR RRT 24 2 Task S WATCHIN 8 aa eei e a e a a pate estab 24 2 Synchronous Nodes eeeeeeeeeceseeececscessecseeaeceeceseeeceseeeeseeeeeeseneeseecaessaeeaees 24 3 Prioritizing Tasks of the Same Priority Level eee eee eseessecsecnseeneeeseees 24 3 Wait Functions for Prioritizing Tasks tees ceceseeeeceseeeeeeeeeeeseeeeeeseneeaes 24 3 VI Sep Priority Seting ee eaaeo neesan eaeoe eucdgeeesteesdueven denver aeetgeues 24 4 Subroutine Priority Level sseseessseesseeesreresrsssseersseersreserrenrerrerreresreresreersrreee 24 4 Reentrant EXecUtion isere oe e E E E E S N 24 5 Examples in which You Should Use Reentrancy seeseeeeeeseeereeereereererrsreees 24 5 Using a VI That Walts snene e s eaen bisi h 24 5 Using a Storage VI Not Meant to Share Its Data eee 24 7 Chapter 25 Managing Your Applications File Arrangement Using VI Libraries seisseen renn e i 25 1 Backing Up Your Fileswis cecc se ne ea ee ee hie ees Me a ed he 25 2 DStei DUNS WIS ies sted n e ea a E N TE sebsstanedy csv stevie NEn EE sasen 25 2 Save with Options Dialog BOX ssseesseseseesesrsssrrrsseersrestrresrerrsseressreresreresrreee 25 3 Designing Applications with Multiple Developers ssssessssesseseeresssrerrsrerrsrreerrrsrreresese 25 5 Keeping Master Copies
542. ssages you send to info LabVIEW request if you want to receive one bulk message daily After you have subscribed to the list you receive postings from other subscribers Traffic in the group is fairly active from 10 to 30 postings per day To post information to the list send e mail to this address info LabVIEW pica army mil How can I load and run Vis dynamically When a subVI exists in the block diagram of another VI the subVI is loaded into memory as soon as the calling VI is loaded into memory For memory considerations you might want to load and unload VIs dynamically from memory during the execution of your program You can use the VI Control VIs to do this These are located in the Functions Advanced VI Control palette For more information on these VIs see the Function and VI Reference located in the Online Reference G Programming Reference Manual B 10 National Instruments Corporation Appendix B Common Questions about G Macintosh In addition to the platform independent VI Control VIs you can use Apple Events on the Macintosh to dynamically load and run VIs The VIs are located in the palette Functions Communication A ppleEvent or its subpalette LabVIEW Specific Apple Events and are called e AESend Finder Open e AESend Open Run Close VI e AESend Run VI e AESend Close VI How do replace a subVI with another VI that has the same name LabVIEW and BridgeVIEW reference all VIs by name and thu
543. string format are C Pascal or G Base your selection of the string format on the type of string that the library function expects Most standard libraries expect either a C string string followed by a character or a Pascal string string preceded by a length byte If the library function that you are calling is written specifically for G then you might want to use the string format which consists of four bytes for length information followed by string data WW Caution Do not attempt to resize a string with system functions such as realloc Doing so can cause your system to crash Calling Functions that Expect Other Data Types In some cases you might encounter a function that expects a data type G does not use For example you cannot use the Call Library Function to pass an arbitrary cluster or an array of non numeric data Depending on the data type you might be able to pass the data by creating a string or array of bytes that contains a binary image of the data that you want to send You can create binary data by typecasting data elements to strings and concatenating them Another option is to write a library function that accepts data types G does use and parameters to build the data structures that the library function expects then calls the library function Finally you can write a code interface node instead Code interface nodes can accept arbitrary data structures but take some time to master because you have to
544. switch the third and fourth pictures are the same but this is not always the case 1 False 2 True 3 TOF 4 FT National Instruments Corporation 22 13 G Programming Reference Manual Chapter 22 Custom Controls and Type Definitions Text Parts When a cosmetic part can have different sized pictures the part has the Independent Sizes option on its pop up menu as shown in the following illustration Copy to Clipboard Import Picture Import at Same Size Revert YEG Sige Picture Item Independent Sizes Independent Sizes is an option you can turn on only when you are in customize mode if you want to move and resize each picture individually without changing the other pictures of the cosmetic part Normally this option is not checked and when you move or resize the current picture of the cosmetic part its other pictures also move the same amount or change size proportionally A text part is a picture with some text The pop up menu for a text part such as a name label has some items identical to those on the pop up menu of a cosmetic part The other items on this menu are the same as the text pop up menu in front panel edit mode An example pop up menu for a text part is shown in the following illustration Copy to Clipboard Import Picture Import at Same Size Revert Sriginaj Siz Size to Test G Programming Reference Manual 22 14 National Instruments Corporation Chapter 22 Custom Controls and Type D
545. t all the units you can use with the units feature Table 9 2 Base Units Quantity Name Unit Abbreviation plane angle radian rad solid angle steradian sr time second s length meter m mass gram g electric current ampere A thermodynamic kelvin K temperature amount of mole mol substance luminous intensity candela cd Table 9 3 Derived Units with Special Names Quantity Name Unit Abbreviation frequency hertz Hz force newton N pressure pascal Pa energy joule J power watt W electric charge coulomb C G Programming Reference Manual 9 28 National Instruments Corporation Chapter 9 Numeric Controls and Indicators Table 9 3 Derived Units with Special Names Continued Quantity Name Unit Abbreviation electric potential volt V capacitance farad F electric resistance ohm Ohm conductance siemens S magnetic flux weber Wb magnetic flux tesla T density inductance henry H luminous flux lumen Im illuminance lux Ix Celsius degree degC temperature Celsius activity becquerel Bq absorbed dose gray Gy dose equivalent sievert Sv Table 9 4 Additional Units in Use with SI Units Quantity Name Unit Abbreviation time minute min time hour h time day d plane angle degree deg National Instruments Corporation 9 29 G Programming Reference Manual Chapter 9 N
546. t buttons to move to the next or previous item Incrementing continues in circular fashion through the list of items as long as you hold down the mouse button You also can select any item directly by clicking on the ring with the Operating tool and then choosing the item you want from the menu that appears Adding Text Items to Rings A new text ring has one item with a value of zero and a display containing an empty string You enter or change text in the ring text area as you do with labels using the Labeling tool Press the lt Enter gt Windows and HP UX or lt Return gt Macintosh and Sun key or click outside the text area to finish typing Add Item After from the text ring pop up menu creates a new empty item following the current one Add Item Before inserts a new item in front of the current item If you are editing item 0 when you select Add Item After for example item 1 is created ready for you to enter text for the new item You also can press lt Shift Enter gt Windows and HP UX or lt Shift Return gt Macintosh and Sun after typing in an item to advance to a new item You add items to the menu ring or dialog ring the same way you add items to the text ring However the menu ring looks and operates like a pull down menu It has no increment buttons You select an item by clicking on the ring and selecting an item from the menu that appears The ring displays the currently selected item You can pop up and select
547. t parts have different pop up menus There are three basic types of parts you can customize e Cosmetic parts such as the slide housing slider and the increment and decrement arrows are the most common Cosmetic parts display a picture e Text parts such as the name label of the slide Text parts consist of a picture for the background usually just a rectangle and some text e Controls as parts such as the slide which uses a numeric control for a digital display Knobs meters and charts also use a numeric control for a digital display Some controls are even more complicated than that for example the graph uses an array of clusters for its cursor display part The following sections describe the different parts and their pop up options in more detail Cosmetic Parts A cosmetic part is a par that has no dynamic user interaction or indication The following illustration shows a pop up menu for a cosmetic part such as a slide housing To pop up on a cosmetic part you National Instruments Corporation 22 9 G Programming Reference Manual Chapter 22 Custom Controls and Type Definitions must be in customize mode You must pop up on the part itself not on the picture of the part in the Control Parts window Copy to Clipboard Import Picture Import at Same Size Revert Grigia Size The following list describes the options available from the pop up menu G Programming Reference Manual Copy to Clipboard Place
548. t platform you might need to use a utility program such as Apple File Exchange on the Macintosh to read the disk You cannot port the following VIs e VIs distributed in the vi 1ib directory Each distribution contains its own vi lib so do not move VIs in vi 1ib across platforms e VIs containing CINs You see an object code not found error if the CIN is from a different platform If you write your CIN source code in a platform independent manner you can recompile it on another platform and relink it to the ported VI e VIs containing the Call Library function The VI can port but is broken unless it can find a library of the same name e Platform specific communication VIs such as AppleEvents on the Macintosh and DDE on Windows e In Port and Out Port Utility VIs for Windows and the Peek and Poke Utility VIs for Macintosh National Instruments Corporation 27 1 G Programming Reference Manual Chapter 27 Portability Issues Porting between Platforms There are several things you can do to ease porting between platforms Portability issues include differences in filenames separator characters resolutions and fonts possible overlapping of labels and differences in picture formats One consideration is the filename Filenames are limited to eight characters plus an optional three character extension typically vi in DOS Windows 3 x and in FAT volumes in Windows NT Macintosh filenames can have 31 characters Windows
549. t the memory is virtual The main difference is speed With virtual memory you occasionally might notice more sluggish performance when memory is swapped to and from the disk by the operating system Virtual memory can help run larger applications but it is probably not appropriate for applications that have critical time constraints Macintosh Memory When you launch an application on the Macintosh the system allocates a single block of memory for it from which all memory is allocated When you load VIs components of those are loaded into that memory Similarly when you run a VI all the memory that it manipulates is allocated out of that single block of memory You configure the amount of memory that the system allocates at launch time using the File Get Info command from the Finder Keep in mind that if your application runs out of memory it cannot increase the size of this memory pool Therefore you should set up this parameter to be as large as is practical If you have a 16 MB machine consider the applications that you want to run in parallel If you do not plan to run any other applications set the memory preference to be as large as possible VI Component Memory Management A VI has four major components e Front panel e Block diagram e Code diagram compiled to machine code e Data control and indicator values default data diagram constant data and so on When you load a VI the front panel the code if it matche
550. t this label the way you want it to look National Instruments Corporation 2 15 G Programming Reference Manual Chapter 2 Building Vis i Note G Programming Reference Manual To display a hidden label pop up on the object and select Show Label from the pop up menu as shown in the following illustration Change to Indicator Find Terminal Show Label Data Operations Unit Label Create Radix Key Navigation Replace Representation Data Range Format amp Precision The label appears waiting for typed input The label disappears if you do not enter text into it before clicking outside the label On the block diagram subVIs do not have labels that you can edit The label of a subVI always shows its name Function labels on the other hand can be edited to reflect the use of the function in the block diagram For example you can use the label of an Add function to document what quantities are being added or why they are being added at that point in the block diagram See the note in the Creating VI Descriptions section in this chapter for related information Text Characteristics You can change text attributes by using the options from the Font ring on the toolbar as shown in the illustration that follows If you select objects or text and make a selection from this ring the changes apply to everything selected If nothing is selected the changes apply to the default font meaning that labels you create fr
551. ta Select a Control For choosing a custom control of your own design Front Panel Control and Indicator Options G Programming Reference Manual When you pop up on a control or indicator on the front panel while editing a VI you see a menu like the one shown in the following illustration The options above the line in the pop up menu are common to all controls and indicators Some controls and indicators do not have any of the options shown below the line Representation Data Range and Format amp Precision in their pop up menus Change to Indicator Find Terminal Show b Data Operations Create Attribute Node Key Navigation Replace Representation Data Range Format amp Precision Objects in the Controls palette initially are configured as controls or indicators For example if you choose a toggle switch from the Boolean palette it appears on the front panel as a control because a toggle switch is usually an input device Conversely if you select an LED it 8 2 National Instruments Corporation Chapter 8 Introduction to Front Panel Objects appears on the front panel as an indicator because an LED is usually an output device However you can reconfigure all controls to be indicators and indicators to controls by choosing the Change to Control or Change to Indicator commands from the pop up menu of the object The Numeric palette contains both a digital control and a digital indicator b
552. taken off the queue until the Wait or I O is complete assigning other tasks possibly with lower priority to execute Notice that as soon as the wait or I O is complete the execution system reinserts the pending task on the queue in front of lower priority tasks Subroutine Priority Level The previous discussion explains how multitasking works with priority levels 0 through 3 If you set a VI to subroutine priority the highest level the behavior is slightly different When a VI runs at subroutine priority no other VI can run until the subroutine priority VI finishes executing even if the other VI is also marked as a subroutine With subroutine VIs the execution system does not multitask execution of VIs In addition subroutine VI execution is streamlined so that front panel controls and indicators are not updated when the subroutine is called Watching a subroutine VI front panel reveals nothing about its execution A subroutine VI might call other subroutine VIs but it might not call a VI with any other priority Use subroutine VIs in situations in which you want to put a simple computation having no interactive elements into a reusable subVI where the call overhead for the subVI is minimized G Programming Reference Manual 24 4 National Instruments Corporation Chapter 24 Understanding the G Execution System Reentrant Execution Under normal circumstances the execution system cannot execute multiple calls to the same subV
553. te Auto indexing with a While Loop that iterates too many times can cause you to run out of memory If you are a LabVIEW user see Chapter 4 Arrays Clusters and Graphs of the LabVIEW Tutorial Manual for further information about building arrays with While Loops to prevent this problem Executing a For Loop Zero Times When you set the count to zero a For Loop does not execute its subdiagram at all The value of all scalar data leaving the For Loop conforms to the following rules e An output array created by auto indexing at an output tunnel is empty e The output from an initialized shift register is the initial value See the Shift Registers section of this chapter for more information e An array passed through a non indexing output tunnel is also empty e All scalars passed through non indexing output tunnels are undefined and you cannot rely on their value The loop count is set to zero or defaults to zero in two ways You can auto index an empty input array or you can wire a zero or a negative number to the count terminal explicitly You must wire to the count terminal unless you auto index an input array When you auto index input arrays or set the loop count with a variable analyze the diagram to determine whether a zero count can occur and if so what the effects would be National Instruments Corporation 18 9 G Programming Reference Manual Chapter 18 Structures Shift Registers Shift registers which ar
554. tects a cycle it displays a dialog box prompting you either to create a new VI from the selection or to cancel If you choose to create a new VI anew Untitled VI is created from your selection The selected items in the original diagram are left untouched Attribute Nodes within Loops Do not include Attribute Nodes within a loop in your selection Because an Attribute Node is retained on the caller VI and wired to the subVI execution of the subVI does not update the value of the attribute on every iteration of the loop You cannot make a subVI in such cases G Programming Reference Manual 3 12 National Instruments Corporation Chapter 3 Building SubVis Illogical Selections Do not convert selections into a subVI that do not make sense For example it does not make sense to convert a selection consisting of one object inside a Sequence Structure and another object outside of the Sequence Structure without including the Sequence Structure itself G disallows such selections and displays an explanation of the problem Locals and Front Panel Terminals within Loops Try to avoid including local variables or front panel terminals inside a loop in your selection Because selected front panel terminals or locals are retained on the caller VI and wired to the subVI execution of the sub VI does not update the value of these items on every iteration of the loop This can cause a change in the functionality of the caller VI G displays a
555. ted in the Numeric Additional National Instruments Corporation 16 3 G Programming Reference Manual Chapter 16 Introduction to the Block Diagram Numerics subpalette The path constant is in the File I O File Constants subpalette The constants are shown in the following illustration First 0 First o a a a iu La mi amp C My HD Gproj You can label your constant by popping up on the constant and selecting Show Label A highlighted text box appears indicating that you can type into it immediately without changing the tool The user defined constants like labels resize automatically as you enter information into them If you resize or change the shape of a label or string constant you can select Size to Text from its pop up menu and the constant or label resizes itself automatically to fit its contents You use the Operating tool to set the value of a user defined constant the same way you set the value of a digital control Boolean slide switch or string control on the front panel The numeric and string constants resemble front panel numeric controls and have pop up menus similar to the pop up menus of controls as shown in the following illustration G Programming Reference Manual 16 4 National Instruments Corporation Chapter 16 Introduction to the Block Diagram Numeric Constant Show Data Operations Replace Representation P Format amp Precision Create Constant Create Control Cre
556. ten to by another diagram during this loop you might use the following diagram instead Notice that you need the shift registers to pass the new value from the subVI to the next iteration of the loop The following diagram is a common mistake that some beginning users make Since there is no shift register the results from the subVI never pass back to the subVI as its new input value National Instruments Corporation 26 11 G Programming Reference Manual Chapter 26 Performance Issues Memory Usage Virtual Memory G handles many of the details which you normally have to worry about in aconventional programming language transparently One of the main challenges of a conventional language is memory usage In a conventional language you the programmer have to take care of allocating memory before you use it and deallocating it when you finish You also have to be particularly careful not to accidentally write past the end of the memory you allocated in the first place Failure to allocate memory or to allocate enough memory is one of the biggest mistakes that programmers make in conventional text based languages Inadequate memory allocation is also a difficult problem to debug The dataflow paradigm for G removes much of the difficulty of managing memory In G you do not allocate variables nor assign values to and from them Instead you create a diagram with connections representing the transition of data Functions th
557. terminals tunnels and selection terminal is available to all cases Cases are not required to use input data or to supply output data but if any case supplies output data all must do so If you do not wire data to an output tunnel from every case the tunnel turns white as in the top example in the following illustration and the run button shows a broken arrow When all cases supply data to the tunnel it turns black as in the bottom example in the following illustration and the run button appears unbroken Incorrect Correct Adding moving and deleting Case subdiagrams are discussed after the following section on the Sequence Structure because these operations are similar for both structures National Instruments Corporation 18 15 G Programming Reference Manual Chapter 18 Structures Sequence Structures The Sequence Structure which looks like a frame of film consists of one or more subdiagrams or frames that execute sequentially For an example of a VI that uses a Sequence Structure see general structs llb TimingTemplate vi Determining the execution order of a program by arranging its elements in sequence is called control flow BASIC C and most other programming languages have inherent control flow because statements execute in the order in which they appear in the program The Sequence Structure is a way of obtaining control flow when data dependencies are not sufficient A Sequence Structure executes frame
558. terminals that connect them to other nodes For example the terminals that feed data into and out of structures are called tunnels Tunnels are relocatable connection points for wires from outside and inside the structures See Chapter 18 Structures for more information Replacing and Inserting Block Diagram Objects Suppose you used an Increment function in the block diagram in which you should have used the Decrement function You can delete the Increment function node and then select the Decrement node from the Functions palette and rewire it You also can use the Replace option in the Increment node pop up menu Selecting Replace accesses the Functions palette from which you can choose the Decrement function The advantage of this method is that the new node is placed where the old node was and does not disturb the wiring You can replace a function with any other function although if the number of terminals or data types in each function node is different you might have broken wires You also can use Replace to replace a constant with another constant or a structure with another similar structure such as a While Loop with a For Loop ir Note When using Replace if you select a VI whose name is the same as one already in memory the replaced node refers to the VI that was already in memory not the VI you selected Wire pop up menus have an Insert option Choosing Insert accesses the Functions palette from which you can choose
559. text parts 22 14 to 22 15 customizing G environment See G environment customizing Cut command Edit menu 2 12 Cut Data option Data Operations menu 11 8 14 13 CVI Function Panel Converter dialog box See LabWindows CVI Function Panel converter cycles avoiding in subVIs 3 12 to 3 13 Attribute Node in Case Structure 3 13 Attribute Nodes within loops 3 12 detection by G 3 12 front panel terminal in Case Structure 3 13 illogical selections 3 13 National Instruments Corporation Index local variable in Case Structure 3 13 locals and front panel terminals within loops 3 13 D Data Log File RefNum 12 3 to 12 5 Data Logging menu 4 5 to 4 6 Change Log File Binding option 4 6 data logging operation 4 5 to 4 6 illustration 4 5 Purge Data option 4 6 data logging on front panel 4 5 to 4 7 changing log file binding 4 6 Data Logging menu 4 5 to 4 6 deleting marked records 4 6 enabling disabling automatic data logging 6 6 marking records for deletion 4 6 retrieving data programmatically 4 7 to 4 9 accessing databases 4 7 to 4 9 halo terminals for accessing data 4 7 4 8 using file I O functions 4 9 viewing records 4 6 to 4 7 waveform charts note 4 6 Data Operations menu Autoscale X 15 13 Autoscale Y 15 13 control pop up menu options 4 2 to 4 3 Copy Data 11 8 Cut Data 11 8 14 13 Description 2 26 Empty Array 14 13 End Selection 14 14 to 14 16 15 33 front panel control and indicator pop
560. that the ticks can be moved as shown in the following illustration In Uniform mode dragging a tick changes the marker distribution In Arbitrary Markers mode dragging a tick moves only the current marker without changing the other markers Pressing the lt Ctr1 gt Windows lt option gt Macintosh lt met a gt Sun or lt Alt gt HP UX National Instruments Corporation 9 17 G Programming Reference Manual Chapter 9 Numeric Controls and Indicators key while dragging creates a new marker If the ticks are hidden as chosen in the Scale Style dialog box you cannot drag them The arbitrary markers affect only the inner markers not the two end markers If no arbitrary markers are visible in the current range the scale reverts temporarily to uniform markers Text Scale You also can use text labels on numeric scales Labels are useful because you can associate strings with integer values This configuration is useful for selecting mutually exclusive options To implement this option select Text Labels from the slide pop up menu The slide control appears with default text labels min and max and you can begin typing immediately to enter the labels you want Press lt Shift Enter gt Windows and HP UX or lt Shift Return gt Macintosh and Sun after each label to create a new label and lt Enter gt on the numeric keypad after you have finished your last label You can use the Labeling tool to edit min
561. the color is set to the color of the largest level less than or equal to the current value National Instruments Corporation 9 25 G Programming Reference Manual Chapter 9 Numeric Controls and Indicators i Note Unit Types The color array always is sorted by level The scale on the ramp corresponds to the largest and smallest values in the array When the minimum or maximum of the scale changes the color array levels are redistributed automatically between the new values The color scale has a number of options which you can display or hide These options include the unit label the digital display and the ramp The ramp component of this control has an extra color at the top and the bottom of the scale You can use these colors to select a color to display if an overflow or an underflow occurs Click on these areas with the Operating tool and select your overflow and underflow colors from the Color palette Both the color ramp and the color box are used to display a numeric value as a color With the color ramp you can assign any range of numbers to any range of colors The color box however displays only the color specified by the red green and blue components of the numeric value any given value always maps to the same color The color ramp can have as many colors as your monitor can handle but no more colors than what are available on your monitor You can use the color scale to indicate color tables for the Intensi
562. the data Number of Samples G Programming Reference Manual 24 8 National Instruments Corporation Chapter Managing Your Applications This chapter contains information about managing your files in G File Arrangement Using VI Libraries You can group multiple VI files by saving them as VI libraries by convention the names of these files end with the extension 11b Or you can save VIs as individual files and group them within directories For a comparison of the two methods see the Saving VIs section of Chapter 2 Building VIs If you use VI libraries you might want to divide your application into multiple VI libraries Put the high level VIs in one VI library and set up other VI libraries to contain VIs separated by function It is easier to manage your VIs if you organize your files in this manner Another reason to break your VIs into multiple VI libraries is because saving files takes longer as the size of your VI library increases When you save a VI into a VI library the library is copied to the temporary directory the VI is compressed and saved into the VI library and the VI library is copied back to the original directory This copying process helps prevent accidental corruption of the original file but it also takes longer to save VIs A good rule of thumb is to avoid creating VI libraries that are larger than 1 MB Notice there is no real limit on the size of a library and the time to load VIs from VI
563. the options for the waveform chart With the Show menu you can show and hide the color scale for the z scale The X Scale and Y Scale menus are identical to the corresponding menus for the waveform chart The intensity chart maintains a history of data from previous updates You can configure this buffer by selecting Chart History Length from the chart pop up menu The default size for an intensity chart is 128 points Notice that the intensity chart display can be very memory intensive For example to display a single precision chart with a history of 512 points and 128 y values requires 512 128 4 bytes size of a single or 256 kilobytes If you want to display large quantities of data on an intensity chart make sure enough memory is available to G The intensity chart supports the standard chart update modes of strip chart sweep chart and scope chart As with the waveform chart you select the update mode from the Data Operations menu Color Mapping You can set the color mapping interactively in the same way that you define the colors for a color ramp numeric control See the description of the color ramp control in Chapter 9 Numeric Controls and Indicators for more details You can set the colors used for display programmatically using the Attribute Node in two ways First you can specify the value to color mappings to the Attribute Node in the same way you do it with the color scale For this method you specify the Z Scal
564. tion Replace Add Dimension Remove Dimension Add Element Gap Reinitialize to Default Make Current Value Default Cut Data Copy Data Paste Data Description Online Help Empty Array Show Last Element Show Selection End Selection SelectAll Find Terminal Show Key Navigation Replace gt Add Dimension Remove Dimension Add Element Gap Reinitialize to Default Make Current Value Default Cut Data Copy Data Paste Data Description Online Help Empty Array Show Last Element Show Selection Start Selection SelectAll 14 15 G Programming Reference Manual Array and Cluster Controls and Indicators Chapter 14 Array and Cluster Controls and Indicators the cells from 1 1 to 3 3 you need to set the index to 4 4 before choosing End Selection After you select cells you can cut or copy the data to paste into other cells When you finish notice that one border line remains highlighted This is an insertion point and remains in the array To hide this line you can deselect the Show Selection option from the pop up menu You can eliminate this line without deselecting Show Selection by emptying the selection Set the index to 0 in all dimensions and then select Start Selection and End Selection This makes the selection run from 0 to 0 in all dimensions which is what the selection is set to when you first place it on the front panel G Arrays and
565. tion Sealing Factors D Engineering Notation HO dH O Relative Time seconds 0 00E 0 LO0E 0 Select the options in this dialog box to set the following graph properties Scale Style Use this option to select major and minor tick marks for the scale Major tick marks are points corresponding to scale labels and minor tick marks are interior points between labels You also use this palette to decide if you want the markers for a particular axis to be visible Mapping Mode Use this option of the scale menus to decide if the scale displays data using a linear or a logarithmic format Grid Options Clicking on these options brings up a palette of grid types to select if you want no gridlines gridlines only at major tick mark locations points corresponding to scale labels or major and minor tick marks minor tick marks are interior points between labels The control next to the grid pop up is a color ring you can use to select the color for the gridlines Scaling Factors You use the scaling factors to specify the initial value and spacing between points on a waveform chart or graph or along the scales of an intensity chart or graph You also can use these National Instruments Corporation 15 15 G Programming Reference Manual Chapter 15 Graph and Chart Controls and Indicators scaling factors to scale your data for display For example if your data was binary sampled data in a range of 2 04
566. tion continue dragging the frame corner outside the window until the dotted frame disappears Then release the mouse button The object maintains its original size Some objects can change size only horizontally or vertically or keep the same proportions when you resize it such as a knob The resizing cursor appears the same but the dotted resize outline moves in only one direction To restrict the growth of any object vertically or horizontally or to maintain the current proportions of the object hold down the lt Shift gt key as you click on the object and drag it Labels You resize labels as you would other objects using the resizing cursor Labels normally autosize that is the box automatically resizes to contain the text you enter Label text remains on one line unless you enter a carriage return or resize the label box Choose Size to Text from the label pop up menu to turn autosizing back on National Instruments Corporation 2 23 G Programming Reference Manual Chapter 2 Building Vis Coloring Objects Front Panel and Block Diagram Work Space To resize the working space to your front panel or block diagram first lt Ctrl click gt Windows lt option click gt Macintosh lt meta click gt Sun lt Alt click gt HP UX and then drag out a region with the Positioning tool You see a rectangle marked by a dotted line which defines your new space Your G development environment appears on the s
567. tional Instruments Corporation Chapter 2 Building VIs Transparency affects only the appearance of an object The object responds to mouse and key operations as usual Some objects have both a foreground and a background that you can color separately The foreground color of a knob for example is the main dial area and the background color is the base color of the raised edge The display at the bottom of the color selection box indicates if you are coloring the foreground the background or both A black border around a square indicates that you have selected that square In the default setting both the foreground and the background are selected To change between foreground and background you can press lt f gt for foreground and lt b gt for background Pressing lt a gt for all selects both foreground and background Pressing any other key also toggles the selection between foreground and background The selection does not toggle until you move the Color tool Selecting the More option from the Color palette accesses a dialog box with which you can customize the colors The More Colors dialog box is shown in the following illustration More Colors x Foreground Red Green Blue Each of the three color components red green and blue describes eight bits of a 24 bit color Therefore each component has a range of 0 to 255 To change the value of a color component you can double click on the display of that col
568. tional Instruments Corporation Chapter 4 Executing and Debugging VIs and SubVIs E O number 0 to number 0 to 1 8 7855E 1 Find Wire Reinitialize to Default Cui Gata Copy Data Paqie prin If you select the Find Wire option the block diagram containing that wire comes to the front of all VIs and the wire is highlighted Use Reinitialize to Default to reset the value displayed in the Probe window to its default value Use the Copy Data option to copy the data to other numeric controls in the same VI or in other VIs Creating Probes When you create a probe you create a default style probe to match the data type of the wire With numeric data types for example a digital indicator is used to probe the data of a wire If you prefer you can select a control for the probe from the built in controls or from controls that have been saved as custom controls or type definitions To do so pop up on the wire select Custom Probe and then select a control from the Custom Probe palette that appears to the right If you choose Select a Control you can use the file dialog box to select any custom control or type definition that was saved in the file National Instruments Corporation 4 25 G Programming Reference Manual Chapter 4 Executing and Debugging VIs and SubVIs system Type definitions are treated just like standard custom controls when used to probe data Description Pig Bape Insert Only t
569. tions that do not produce bad wires but do make the block diagram difficult to read or make it appear to do things it actually does not do Remember when you are unsure of what connects to a wire you can double click on the wire to select the branch or triple click to select the entire wire Looping Wires A loop of wire is not an error but is a poor design because it unnecessarily clutters the diagram Double click on one of the branches to select it then delete it A wire loop is shown in the following illustration li National Instruments Corporation 17 15 G Programming Reference Manual Chapter 17 Wiring the Block Diagram Hidden Wire Segments Try to avoid wiring under a structure border or between overlapped objects because some segments of the resulting wire might be hidden An example of hidden wire segments is shown in the following illustration You can create hidden wire segments inadvertently such as when you move a tunnel or enlarge a structure as shown in parts and 2 of the preceding example Parts 3 and 4 of this example show one way you can make this diagram less confusing You can drag the wire segment connected to the constant so that the hidden wire segments reappear Press the lt Shift gt key to constrain the wire drag and reduce the likelihood of creating loose ends G Programming Reference Manual 17 16 National Instruments Corporation Chapter 17 Wiring the Block Diagram Wiring underneath
570. tity Extended Precision Complex 1E lt nn gt xx1E lt k gt lt k base exp gt Physical Quantity A 9 G Programming Reference Manual National Instruments Corporation Data Storage Formats Appendix A Data Storage Formats Table A 2 _Non Numeric Data Types Data Type Type Code Type Descriptor Boolean 20 0004 xx20 String 30 0004 xx30 Handle 31 0006 xx31 lt kind gt Path 32 0004 xx32 Pict 33 0004 xx33 Array 40 lt nn gt 0x40 lt k gt lt k dims gt lt element type descriptor gt Cluster 0x50 lt nn gt 0x50 lt k gt lt k element type descriptors gt The minimum value in the size field of a type descriptor is 4 as shown in the first table However any type descriptor can have a name appended a Pascal string in which case the size is larger by the length of the name Notice that the array and cluster data types each have their own type code They also contain additional information about their dimensionality for arrays or number of elements for clusters as well as information about the data types of their elements In the following example of an enumerated type for the items am fm fm stereo each group represents a 16 bit word The space enclosed in quotes represents an ASCII space 0016 0015 0003 02a m02 fm 09f m st er eo 0016 indicates 22 bytes total 0015 indicates an enumerated byte 0003 indicates that there are three items In the following example of
571. tly This is in addition to the fact that a more hierarchical organization to your VIs is generally easier to maintain and read i Note If the front panel or block diagram of a given VI is much larger than a screen you might want to break it into subVIs to make it more accessible Dataflow Programming and Data Buffers In dataflow programming you do not generally use variables Dataflow models usually describe nodes as consuming data inputs and producing data outputs A literal implementation of this model would produce applications that can use very large amounts of memory and have sluggish performance Every function would produce a copy of data for every destination to which an output is passed The compiler improves on this implementation by attempting to determine when memory can be reused and by looking at the destinations of an output to determine whether it is necessary to make copies for each individual terminal For example in a more traditional approach to the compiler the following diagram would use two blocks of data memory one for the input and one for the output Input Array i _ Output Array G Programming Reference Manual 26 14 National Instruments Corporation Chapter 26 Performance Issues The input array and the output array contain the same number of elements and the data type for both arrays is the same Think of the incoming array as a buffer of data Instead of creating a new buffer for the outp
572. to scroll windows Terminal that passes data between the frames of a Sequence Structure G 11 G Programming Reference Manual Glossary Sequence Structure shared external routine shift register sink terminal slider source terminal string controls and indicators strip chart structure stub VI subdiagram subVI sweep chart T table driven execution terminal G Programming Reference Manual Program control structure that executes its subdiagrams in numeric order Commonly used to force nodes that are not data dependent to execute in a desired order Subroutine that can be shared by several CIN code resources Optional mechanism in loop structures used to pass the value of a variable from one iteration of a loop to a subsequent iteration Terminal that absorbs data Also called a destination terminal Moveable part of slide controls and indicators Terminal that emits data Front panel objects used to manipulate and display or input and output text A numeric plotting indicator modeled after a paper strip chart recorder which scrolls as it plots data Program control element such as a Sequence Case For Loop or While Loop A nonfunctional prototype of a subVI It has inputs and outputs but is incomplete It is used during early planning stages of a VI design as a place holder for future VI development Block diagram within the border of a structure VI used in the block diagram of anoth
573. to the x power minus one e 1 floor x Round to Infinity Truncates x to the next lower integer largest int is smaller than or equal to x getexp x Mantissa amp Exponent Returns the exponent of x getman x Mantissa amp Exponent Returns the mantissa of x int x Round To Nearest Rounds its argument to the integer nearest even integer intrz x Round Toward 0 Rounds x to the nearest integer between x and zero In x Natural Logarithm Computes the natural logarithm of x to the base e G Programming Reference Manual 19 6 National Instruments Corporation Chapter 19 Formula Nodes Table 19 1 Formula Node Functions Continued Function Corresponding G Description Function Name Inp1 x Natural Logarithm Computes the natural logarithm Arg 1 of x 1 log x Logarithm Base 10 Computes the logarithm of x to the base of 10 log2 x Logarithm Base 2 Computes the logarithm of x to the base 2 max x y Max amp Min Compares x and y and returns the larger value min x y Max amp Min Compares x and y and returns the smaller value mod x y Quotient amp Remainder Computes the remainder of x y when the quotient is rounded toward Infinity rand Random Number Produces a floating point number 0 1 between 0 and 1 exclusively rem x y Remainder Computes the remainder of x y when the quotient is rounded to the nearest integer sec x
574. tomatically imports the picture to the G Clipboard Or you can use the Import Picture from File option from the Windows Edit menu to import a graphics file into the G Clipboard In Windows 3 1 you can use the latter method on CLP EMF GIF PCX BMP TARGA TIFF LZW WMF and WPG files On Windows 95 NT you can use EMF WMF and CLP files Macintosh If you copy from a paint program to the Clipboard and then switch to G G automatically imports the picture to its Clipboard UNIX You can use the Import Picture from File option from the UNIX Edit menu to import a picture of type X Window Dump XWD which you can create using the xwd command All Platforms When a picture is on the G Clipboard you can paste it as a static picture on your front panel or you can use the Import Picture option of a pop up menu or the Import Picture options in the Control Editor For an example of how to import graphics from other programs see general controls custom 11lb National Instruments Corporation 8 11 G Programming Reference Manual Chapter Numeric Controls and Indicators This chapter explains how to create operate and configure the various styles of numeric controls and indicators When you select Controls Numeric from the palette a new palette of controls and indicators appears as shown in the following illustration 10 0 oy og 14 4 1 ON O aor oo dwd og toto oy d oy dih pod Ea e Wa 10 a AL i
575. tomizing Your G Environment Installing and Changing Views Palettes Editor Controls and Functions palette information is stored in the menus directory of the directory of your application The menus directory contains directories corresponding to each view that you create or install This organization makes it easy to transfer views to other people To give someone else a copy of a view give the person a copy of the directory of the view from the menus directory After placing it in his or her menus directory the view becomes available To switch to another view select Edit Edit Control amp Function Palettes Then select the view that you want from the menu setup ring To create your own view see the description in the following Palettes Editor section For more details on how views are organized see the How Views Work section later in this chapter For more control over the layout and contents of the Controls and Functions palettes use the Edit gt Edit Control amp Function Palettes option When you have selected this option you enter the Palettes Editor The Edit Palettes dialog box appears In this editor you can rearrange the contents of palettes by dragging objects to new locations If you want to delete customize or insert objects pop up on a palette as shown in the following illustration or pop up on an object within a subpalette Insert Submenu Move Submenu Custom Control s Delete Sub
576. top command aborts the top level VI at the Stop button earliest opportunity The halted VI most likely did not complete its task so you cannot rely on any data it produces Although G closes files open at the time and halts any data acquisition that might be in progress you should avoid designing VIs that rely on the Stop button or Stop menu option For example if you create a VI that executes indefinitely within a While Loop until stopped by the operator wire the conditional terminal of the loop with a Boolean switch on the front panel If you want to prevent an operator from inadvertently aborting your VI by clicking on the Stop button hide it by deselecting the VI Setup Window Options Show Abort Button option from the icon pane pop up menu on the front panel of the VI See Chapter 6 Setting up VIs and SubVIs for information on setting window options G Programming Reference Manual 4 4 National Instruments Corporation Chapter 4 Executing and Debugging Vis and SubVIs Running Vis Repeatedly Run Continuously button l VI running continuously To execute a VI repeatedly click on the Run Continuously button The VI begins executing immediately and the Run Continuously button changes from outlined arrows to filled arrows while the VI is running Click on the Run Continuously button again to stop the VI The VI stops when it has completed normally The behavior of the VI and the state of the toolbar during continuous r
577. tors For a Single Selection Listbox you have selection mode options to set the listbox to support zero or one selections or one selection shown in the following illustration Change to Indicator Find Terminal Show b Data Operations gt Create gt Key Navigation Replace gt Selection Mode 0 or 1 litem Keyboard Mode gt 1 Item 0 or More Items 1 or More Items Disable Item tem Symbol If you select 1 Item the default setting then one option in the listbox always is selected highlighted When you click on a different option the new option is selected highlighted and the previous option is deselected If you select 0 or 1 Item the behavior is the same with the exception that a user can deselect the current option by lt Shift gt clicking on it leaving no options selected In a Multiple Selection Listbox you have the same selection mode options as the Single Selection Listbox In addition you can indicate that multiple options can be selected as shown in the following illustration Selection Mode Dori item 1 Item lt O or More Items 1 or More Items By default the Multiple Selection listbox has a selection mode in which the user can select 0 or More Items You also can select 0 or More Items to put it into a multiple selection mode where at least one item must be selected National Instruments Corporation 13 5 G Programming Reference Manual Chapter 13 List a
578. tors The rotary objects have most of the same options as the slide The sliders or needles in rotary objects turn rather than slide but you operate them the same way you operate slides Rotary controls like linear controls can display more than one value as shown in the preceding illustration You add new values by selecting Add Needle from the pop up menu in the same way you add new values to slides If you move the Positioning tool to the scale the tool changes to a rotary cursor If you click on and drag the outer limits of the scale you can change the arc that the scale covers If you click on and drag the inner markers of the scale you can rotate the arc it still has the same range but different starting and ending angles This procedure is shown in the following illustration Hold down the lt Shift gt key to snap the arc to 45 degree angles Place the cursor on the knob scale where it changes appearance to a double arrow horseshoe G Programming Reference Manual 9 22 National Instruments Corporation Chapter 9 Numeric Controls and Indicators Dragging outer markers changes the size of the scale arc Tick marks of rotary scales can be dragged with the Operating tool just like linear scales Ticks also can be unevenly distributed in a similar manner to linear scales See the section Selecting Non Uniform Scale Marker Distribution for more information For more information on ring controls and indicators s
579. tory note 2 29 copying original VI note 2 28 editing after saving note 2 28 individual VI files 2 28 to 2 29 saving for distribution 25 3 to 25 4 VI libraries LLBs 2 29 to 2 30 scalar data types flattened data A 13 non numeric table A 10 Scale Block Diagram to Fit option 5 4 Scale Front Panel to Fit option 5 4 scale markers 9 15 to 9 18 Arbitrary Markers mode 9 17 changing scale limits 9 16 nonuniform deleting 9 16 to 9 18 moving 9 17 selecting non uniform distribution 9 16 to 9 18 Uniform Markers mode 9 17 scale options graph indicators 15 12 to 15 17 Formatting 15 15 to 15 17 Marker Spacing 15 13 to 15 14 scale parts 22 15 Scale pop up menu 9 14 to 9 15 Format amp Precision 9 15 illustration 9 14 Mapping 9 15 Marker Spacing 9 14 Style 9 15 Scale Style option 15 15 Scale to Fit option 5 4 Scaling Factors option 15 15 to 15 16 scope chart update mode 15 27 National Instruments Corporation screen display performance considerations 26 7 Scroll tool 2 5 Scrollbar option color settings 7 13 string controls and indicators 11 3 search path for VIs setting 7 5 to 7 6 Search Results command 3 28 Search Results window 3 28 to 3 29 Clear option 3 28 Find option 3 28 Go to option 3 28 Stop option 3 29 search string options Match Case 3 26 Match Whole Word 3 26 Regular Expression 3 26 searching for VIs objects and text See Find dialog box section headers printing
580. tributes yc santo ei he eG eis E AEN 20 7 Visible Attribute enere sns pere eas aeara ae ao TNE HEESE ii En 20 7 Disabled Attribute i sese oueienn neran asa is ERRE 20 7 Key Foc s Attn Bute seinninn a ER 20 8 Blinking Attribute soni neneke aer E ea E EEES 20 8 Position Atribute cate oa eaea a Saa Sni EA 20 9 Bounds Attribute Read Only eesseseessesssessesesessessesesessereseeserseeseesee 20 10 Examples of Attributes Specific to Controls or Indicators eee 20 10 Changing Plot Color on a Chart 0 0 ice ce eeeecseesseeeeseeesecseessecneesneenees 20 10 Setting the Strings of a Boolean Attribute 0 ee eeeeeeeeeneeeeee 20 11 Setting the Strings of Ring Controls 0 ec eceeeeecseeecneeeseeeeeeeees 20 12 Using a Double Clicked Listbox Item wo ee cece ceeeeseeeeeneees 20 13 Selectively Presenting Users with Options eee cece eeeeeeee 20 14 Reading Graph Cursors Programmatically 0 00 eeeseeeseeeeeenee 20 14 National Instruments Corporation XV G Programming Reference Manual Table of Contents Chapter 21 Global and Local Variables Global Variable Saa t a n a See awe aE saab Haste So wna ata 21 1 Poca RS F219 i ee ene oe ae a o o a tereni 21 3 Advanced Topics Chapters 22 through 27 Chapter 22 Custom Controls and Type Definitions CUSTOM Control s ssc 5 piectac ee Haweiee R oes is Seen E E its eventos ear ee eee Lee 22 1 Using the Control Editor oo eee eee ceesecscessececsseeeceseesecneeseseeeeseseaeea
581. trols accept only the following decimal digits a decimal point uppercase or lowercase e and the terms Inf infinity and NaN not a number and in absolute time format the following characters and uppercase or lowercase a m p and m If you exceed the limit for the selected representation G coerces the number to the natural limit For example if you enter 1234 into a control set for byte integers G coerces the number to 127 If you incorrectly enter non numeric values such as aNN for NaN or I fn for Inf G passes over them and uses the previous value The increment buttons usually change the ones digit Increasing a digit beyond 9 or decreasing below 0 affects the appropriate adjacent digit G Programming Reference Manual 9 2 National Instruments Corporation Chapter 9 Numeric Controls and Indicators Increasing and decreasing repeats automatically If you click on an increment button and hold the mouse button down the display increases or decreases repeatedly If you hold the lt Shift gt key down while increasing the value repeatedly the size of the increment increases by successively higher orders of magnitude For example by ones then by tens then by hundreds and so on As the range limit approaches the increment decreases by orders of magnitude slowing down to normal as the value reaches the limit In a digital control for time and date individual components second minute hour day month year as
582. tronic services include a bulletin board service an FTP site a FaxBack system and e mail support If you have a hardware or software problem first try the electronic support systems If the information available on these systems does not answer your questions we offer fax and telephone support through our technical support centers which are staffed by applications engineers Electronic Services Bulletin Board Support National Instruments has BBS and FTP sites dedicated for 24 hour support with a collection of files and documents to answer most common customer questions From these sites you can also download the latest instrument drivers updates and example programs For recorded instructions on how to use the bulletin board and FTP services and for BBS automated information call 512 795 6990 You can access these services at United States 512 794 5422 or 800 327 3077 Up to 14 400 baud 8 data bits 1 stop bit no parity United Kingdom 01635 551422 Up to 9 600 baud 8 data bits 1 stop bit no parity France 01 48 65 15 59 Up to 9 600 baud 8 data bits 1 stop bit no parity FTP Support To access our FTP site log on to our Internet host ftp natinst com as anonymous and use your Internet address such as joesmith anywhere com as your password The support files and documents are located in the support directories National Instruments Corporation C 1 G Programming Reference Manual FaxBack Support FaxBack
583. tructure or VI and pause The keyboard shortcut is lt Ctrl gt Windows lt command gt Macintosh lt meta gt Sun or lt Alt gt HP UX followed by the up arrow key When the VI finishes executing the step buttons become grayed out G Programming Reference Manual 4 20 National Instruments Corporation Chapter 4 Executing and Debugging VIs and SubVIs Reading Call Chains When a subVI is paused a Call Chain ring appears This menu lists the chain of callers from the top level VI down to this subVI but keep in mind that this is not the same as the Project This VI s Caller s option which lists all calling VIs regardless of whether they currently are executing When you select a VI from the Call Chain ring its block diagram opens and the VI calling the current subVI is selected This helps you distinguish the current instance of the subVI if the block diagram contains more than one instance Caller wi TY Call Chain ring In addition to the keyboard shortcuts given in the Using Step Buttons the following commands are available e When single stepping through a subVI or structure clicking on the Step Out button while holding the mouse down brings up a menu from which you can select how far the VI should execute before pausing e Double clicking on front panel controls and indicators local variables and global variables displays and highlights the corresponding block diagram object e Pressing the lt Ctrl gt
584. ts Corporation B 5 G Programming Reference Manual Appendix B Common Questions about G Platform Issues and Compatibilities What is required to transfer Vis between platforms When a VI file is brought to another platform no conversion is necessary for LabVIEW or BridgeVIEW to read it When G opens the VI it recognizes that it has been compiled for a different platform and recompiles it for the new platform This means that you must include the block diagram of a VI if you want to take it to another platform For VIs containing CINs you need to recompile the CINs on the new platform and then relink them to the ported VI You should eliminate platform specific functions for example Apple Events for Macintosh DDE for Windows and so on before you port a VI to another platform You can move VIs between platforms using networks modems and disks VIs are saved in the same file format on all platforms If you transfer VIs across a network using ftp or modem make sure that you specify a binary transfer If disks are the method of transfer you need disk conversion utilities to read the disks from other platforms Conversion utilities change the format of files stored on disk because each platform Macintosh Windows Sun saves files to disk in a different format Most file conversion utilities not only read files from another platform but also write files in the disk format of that platform For example there are utilities such as Ma
585. tton 4 1 pencil tool Icon Editor 3 3 Performance and Disk Preferences dialog box 7 6 to 7 9 Check available disk space during launch 7 9 Compact memory during execution 7 8 Cooperation level 7 9 Deallocate memory as soon as possible 7 7 illustration 7 7 Performance and Disk dialog box 7 7 Use default timer 7 7 to 7 8 performance issues efficient data structures 26 28 to 26 36 alternative implementations 26 33 to 26 35 avoiding complicated data types 26 30 to 26 32 global table of mixed data types 26 32 to 26 35 obvious implementation 26 33 static global table of strings 26 35 to 26 36 National Instruments Corporation memory usage 26 12 to 26 36 basic concepts 26 12 consistent data types 26 22 to 26 28 building arrays example 26 24 to 26 26 searching through strings example 26 27 to 26 28 dataflow programming and data buffers 26 14 to 26 17 deallocation 26 21 to 26 22 front panels 26 19 to 26 20 general rules for improving 26 18 to 26 19 global variables 26 21 input buffer reuse by output 26 22 local variables 26 20 to 26 21 Macintosh memory 26 13 monitoring 26 17 to 26 18 overview 26 12 subVI reuse of data memory 26 20 VI components 26 13 to 26 14 virtual memory 26 12 to 26 13 Profile window 26 1 to 26 5 illustration 26 2 memory information 26 5 Reset button 26 2 Save button 26 2 Snapshot button 26 2 Start button 26 2 SubVI s Time 26 3 timing information 26 4 to 26 5
586. tton pauses execution You can press it again at any time to continue execution National Instruments Corporation 4 1 G Programming Reference Manual Chapter 4 Executing and Debugging VIs and SubVIs Run button You can run multiple VIs at the same time After you start the first one switch to the front panel or block diagram of the next one and start it as described previously Notice that if you run a subVI as a top level VI all caller VIs are broken until the subVI completes You cannot run a subVI as a top level VI and as a subVI at the same time If your VI runs but does not perform correctly see the sections Debugging Broken VIs and Debugging Executable VIs later in this chapter When you edit a VI the toolbar contains several tools used for editing VIs including the Font ring the Alignment ring and the Distribution ring 22 ball Loot Anolication Fonk Eok aol When you run a VI those tools are replaced with debugging tools as shown in the following illustration If you pop up on a control while running a VI you can see that all objects have a much simpler set of options These are the same as the options in the Data Operations submenu that you see in pop up menus when you edit VIs Reinitialize to Default Pit PREG Copy Data Pasta aia Description ppiinpp Hein Find Control G Programming Reference Manual 4 2 National Instruments Corporation Chapter 4 Executing and Debugging Vis an
587. ty Graph and Intensity Chart controls See Chapter 15 Graph and Chart Controls and Indicators for more information on these controls Any numeric control can have physical units such as meters or kilometers second associated with it Any numeric control with an associated unit is restricted to a floating point data type Units for a control are displayed and modified in a separate but attached label called the unit label You can show this label by selecting the option from the pop up menu as shown in the following illustration G Programming Reference Manual 9 26 National Instruments Corporation Chapter 9 Numeric Controls and Indicators Change to Indicator Find Terminal Show d Lobel Data Operations Unit Label Create Attribute Node Radix E When the unit label is displayed you can enter a unit using standard abbreviations such as m for meters ft for feet s for seconds and so on If you are not familiar with which units are acceptable enter a simple unit such as m then pop up on the unit label and select Unit A dialog box appears that contains information about the units that are available You can use this dialog box to replace your first unit with a more appropriate choice The following numeric control is set to have units of meters per second National Instruments Corporation 9 27 G Programming Reference Manual Chapter 9 Numeric Controls and Indicators Table 9 6 1 through Table 9 6 5 lis
588. type definition if you change the strict type definition to an integer you automatically update every VI that uses it or you can check to make sure if they need to be updated Unlike the general type definition however other changes to the strict type definition such as changing the red frame color to blue also requires VIs using the strict type definition to be updated Note Many Attribute Nodes are not available for strict type definitions However the attributes that are available for strict type definitions are those that affect the appearance of the control such as Visible Disabled Key Focus Position and Bounds Creating Type Definitions You make a type definition by setting the ring on the toolbar in a Control Editor window as shown in the following illustration Set up the control the way you want it and choose File Save in the Control Editor window Ej control __Jrtapstoatonront jE T ype Def y Strict Type Def You can open any type definition you have saved by selecting File Open A type definition always opens in a Control Editor window Any changes you make to a type definition affect all VIs that are using it Using Type Definitions Place general type definitions and strict type definitions on the front panel of a VI as you would any custom control You can edit and operate a type definition on your front panel as you would any other control Note You cannot edit a strict type definition on
589. u are LabVIEW user see the Alignment Considerations section of Chapter 2 CIN Parameter Passing of the LabVIEW Code Interface Reference Manual for further information The illustrations that follow show a cluster containing a single precision floating point number an extended precision floating point number and a handle to a one dimensional array of unsigned word integers presented in that order For more information see Chapter 14 Array and Cluster Controls and Indicators e Windows SGL float ET float Handle to Array e Macintosh SGL float 4 EXT float Handle to Array e Sun SGL float O S EXT float Handle to Array G Programming Reference Manual A 6 National Instruments Corporation Appendix A Data Storage Formats e HP UX SGL float 2 EXT float Handle to Array In the next example the embedded clusters are not stored indirectly Instead the data is stored inside the embedded clusters directly as if the data were not embedded in the subcluster Only arrays strings and handles are stored indirectly ET 32 bit float P 32 bit float ul p 32 bit int Handie to Array 32 bit int Type Descriptors Each wire and terminal in the block diagram has a data type associated with it You can keep track of this type with a structure in memory called a type descriptor This descriptor is a string of word integers that can describe any data typ
590. u should avoid overusing local and global variables When you read from a global variable a copy of the data of the global variable is generated Thus a complete copy of the data of the array is being generated each time you access an element The next method shows an even more efficient method that avoids this overhead Alternative Implementation 2 There is an alternative method for storing global data and that is to use an uninitialized shift register Essentially if you do not wire an initial value a shift register remembers its value from call to call If you are a National Instruments Corporation 26 33 G Programming Reference Manual Chapter 26 Performance Issues LabVIEW user and are not familiar with uninitialized shift registers see Chapter 3 Loops and Charts of the LabVIEW Tutorial Manual before continuing with this discussion If you are a Bridge VIEW user see Chapter 10 Loops and Charts in your BridgeVIEW User Manual for similar information The compiler handles access to shift registers efficiently Reading the value of a shift register does not necessarily generate a copy of the data In fact you can index an array that is stored in a shift register and even change and update its value without generating extra copies of the overall array The only problem with a shift register is that only the VI that contains the shift register can access the data of the shift register On the other hand the shift register has the
591. u want to pass a refnum between two VIs If you are a LabVIEW user refer to Chapter 5 VISA Transition Library Reference in the LabVIEW Instrument I O VI Reference Manual for information on the two VISA refnums There are two kinds of file refnums one for datalog files and one for byte stream files Because datalog files have an inherent structure the Data Log File RefNum is used to pass the refnum as well as a description of the file type to or from calling VIs The Data Log File RefNum is resizeable like a cluster You place a control inside the refnum that defines the National Instruments Corporation 12 3 G Programming Reference Manual Chapter 12 Path Controls and Indicators and Refnums structure of the file For a file that contains numbers you create a datalog refnum containing a number If each record in the file contains a pair of numbers you place a cluster inside the refnum and then place two numeric controls inside the cluster The remaining refnums are easy to use because they do not have any options The Byte Stream File RefNum is used with byte stream files either text or binary files Typically you use it when you open or create a file in one VI but want to perform I O on the file in another VI You need a refnum control on the front panel of the VI that performs I O and a refnum indicator on the front panel of the VI that opens or creates the file The Device RefNum is used with the device I O functions
592. ugh the Edit Preferences Front Panel dialog box It can be turned on or off for individual graphs from their pop up menus G Programming Reference Manual B 2 National Instruments Corporation Appendix B Common Questions about G How do update a graph without clearing it All the graphs waveform XY and intensity always clear before writing new data however it is a simple procedure to keep track of the data previously written to the graph and append new data with each write The general arrays llb Separate Array Values vi demonstrates the technique of using the Build Array function to append new values to an array If you are a LabVIEW user refer to Chapter 4 Arrays Clusters and Graphs of the LabVIEW Tutorial Manual How can create a bar graph See the examples in general graphs bargraph 11lb This VI library contains an example bar graph and two VIs you can use to create bar graphs out of an array input The G Picture Control Toolkit also can create bar graphs How can create polar plots and Smith charts The G Picture Control Toolkit contains examples with routines to create polar plots and Smith charts The toolkit is a versatile graphics package for creating arbitrary front panel displays The Picture VI Library which ships with the toolkit implements a common set of drawing commands for building the graphic images How can make a label for the y axis that is rotated 90 degrees Bridge VIEW and LabVIEW d
593. ultiply has executed And in the following example the For Loop has a breakpoint The VI will pause after Multiply has executed G Programming Reference Manual 4 28 National Instruments Corporation Chapter 4 Executing and Debugging Vis and SubVIs When a VI pauses because of a breakpoint its block diagram is brought to the front if the front panel was closed it is opened as well and the node or wire that caused the break is highlighted with a marquee Breakpoints are saved with a VI but only become active during execution Suspending Execution You can edit indicators execute the subVI as many times as you want before returning to the caller or go back to the beginning of the subVI by suspending execution of a SubVI To set a subVI in suspend mode open the subVI and check the Operate Suspend when Called option This option also can be accessed by popping up on the connector pane on the front panel while in run mode and selecting Setup Execution Options Suspend when Called The subVI automatically suspends when it is called If you check this option when single stepping the VI does not switch into suspend mode immediately If you want to suspend execution at a particular call to a subVI use the SubVI Node Setup option from the pop up menu of the subVI node instead of the Suspend when Called option The SubVI Node Setup suspends execution at that particular instance of the subVI only Recognizing Auto
594. umeric Controls and Indicators Also keep in mind that you cannot enter ambiguous units Thus m ss is flagged in the following illustration because it is not clear if it means meters per second squared or meters seconds seconds To resolve ambiguity you have to enter the units differently as shown in the three examples to the right You cannot select units for a chart or graph unless you wire them to an object that has an associated unit Then you can show the unit that the chart or graph has acquired through the connection You can change this unit to another unit that measures the same phenomenon but not to a unit measuring a different class of quantity or quality For example if an input to a chart carries the unit mi you can edit the chart unit to ft in or m but not to N Hz min acre or A G Programming Reference Manual 9 32 National Instruments Corporation Chapter 9 Numeric Controls and Indicators Units and Strict Type Checking A wire connected to a source that has a unit associated with it can connect only to a destination with a compatible unit as shown in the following illustration In the case of the previous illustration the distance display is scaled automatically to display kilometers instead of meters because that was the specified unit for the indicator You cannot connect signals with incompatible units as shown in the following illustration If you select List Errors from the pop u
595. umeric Controls and Indicators Table 9 4 Additional Units in Use with SI Units Continued Quantity Name Unit Abbreviation plane angle minute plane angle second volume liter l mass metric ton t area hectare ha energy electron eV volt mass unified u atomic mass unit Table 9 5 CGS Units Quantity Name Unit Abbreviation area barn b force dyne dyn energy erg erg pressure bar bar Table 9 6 Other Units Quantity Name Unit Abbreviation Fahrenheit temperature degree Fahrenheit degF Celsius temperature Celsius degree Cdeg difference G Programming Reference Manual 9 30 National Instruments Corporation Chapter 9 Numeric Controls and Indicators Table 9 6 Other Units Continued Quantity Name Unit Abbreviation Fahrenheit temperature Fahrenheit degree Fdeg difference length foot ft length inch in length mile mi area acre acre pressure atmosphere atm energy calorie cal energy British thermal unit Btu Entering Units If you try to enter an invalid unit into a unit label G flags the invalid unit by placing a in the label as shown in the following illustration Notice that you must enter units using the correct abbreviations or G flags it as shown in the following illustration National Instruments Corporation 9 31 G Programming Reference Manual Chapter 9 N
596. un is the same as during a single run started with the Run button or the Operate Run command Data Logging on the Front Panel Front panel data logging logs a time stamp and the data in all front panel controls of a VI to a separate datalog file You can have several separate files each filled with logged data from different tests You can retrieve this data using interactive retrieval through the VI programmatic data retrieval or standard file I O functions Each VI maintains a log file binding which shows where the datalog file to which it will log front panel data resides If the binding is clear meaning that the location is unspecified the VI prompts you for the location of the file Configure and control front panel data logging by selecting the Operate menu and its Data Logging submenu as shown in the following illustration roject Windows Help tion Forlad zolz Print at Completion Log at Completion Data Logging Log Suspend when Called Retrieve Purge Data Make Current Values Default Change Log File Binding Reinitialize All To Default Clear Log File Binding Change to Run Mode Ctrl M CF National Instruments Corporation 4 5 G Programming Reference Manual Chapter 4 Executing and Debugging VIs and SubVIs When automatic data logging is enabled for a VI G logs the front panel of the VI any time the VI completes execution You can tell if automatic data logging is enabled for a VI by looking at t
597. up menu 8 3 Make Current Value Default 14 21 object pop up menu options 4 3 to 4 4 Paste Data 11 8 Reinitialize to Default Values 14 21 Show Last Element 14 13 G Programming Reference Manual Index Show Selection 11 9 Smooth Updates 15 13 Start Selection 14 14 to 14 16 15 33 Update Mode 15 26 Data Range dialog box 9 7 Data Range option 4 14 9 15 14 12 data storage formats arrays A 3 to A 5 Boolean A 1 clusters A 5 to A 7 numeric A 1 to A 3 paths A 5 strings A 5 data tables See tables data types arrays 23 6 to 23 7 avoiding complicated data types in structures 26 30 to 26 32 calling functions that expect non G data types 23 7 examples A 10 to A 11 listbox items 13 3 memory considerations avoiding constant resizing of data 26 24 to 26 28 consistent data types 26 22 to 26 23 building arrays example 26 24 to 26 26 searching through strings example 26 27 to 26 28 generating data of right type 26 23 to 26 24 numerics 23 6 printing control data type 5 6 scalar numeric table A 8 to A 9 storage of physical quantities note A 11 strings 23 7 void 23 5 waveform graph data types multiplot graph 15 4 to 15 9 single plot graph 15 2 to 15 3 G Programming Reference Manual 1 26 XY graph data types multiplot graph 15 9 to 15 11 single plot graph 15 3 to 15 4 data dependent execution 1 5 data driven execution 1 5 dataflow programming data buffers 26 14 to 26 17 overview 1 5
598. ursor on a wire or pop up on the wire and select Probe As shown in the following illustration the floating Probe window appears with no data displayed within As soon as you run the VI the Probe window displays data passed along the wire iO number 0 to number O to 1 2 7555E 1 Each probe is numbered automatically and uniquely The wire to which itis attached is marked with the same number This helps you keep track of which probe is associated with which wire However if the name of the front panel control is as long as or longer than the Probe window the number is not visible You can use the probe in conjunction with execution highlighting single stepping or breakpoints to view values more easily During single stepping or pausing at a breakpoint data is updated immediately if it is available Then you can examine the inputs of a node when execution halts at the node You can insert the probe before running your VI to see the data In single stepping you also can create a probe for a wire that has executed and it updates to show the contents of the wire This is useful when you have set a breakpoint on a node and you want to examine its inputs You cannot change data with the probe and the probe has no effect on VI execution If you pop up on the indicator of the Probe window you can find the associated wire by selecting Find Wire as shown in the following illustration G Programming Reference Manual 4 24 Na
599. use the Insert Submenu option from the pop up menu in the Palettes Editor When you select this option you are presented with the following dialog box National Instruments Corporation 7 27 G Programming Reference Manual Chapter 7 Customizing Your G Environment Insert Submenu eo Create a new menu file mnu 4 Link to an existing menu file mnu 4 Link to a library Tb a Link to a directory You can store submenu information in VI libraries or in mnu files A menu file or LLB can contain one Functions palette and one Controls palette Select Create a new menu file to insert a new empty palette You then are prompted for a name for the palette and a file to contain it It is recommended that you add a mnu extension to the file to indicate that itis a menu palette In addition it is recommended that you either store the mnu file in the directory of your view in the menus directory or in the same directory that contains the controls or VIs that the menu largely represents Select Link to an existing menu file if you have an existing palette that you want to add to the Controls or Functions palette file Select Link to a directory if you want to create a palette with entries for all the files in the directory Selecting this option also recursively creates subpalettes for each of the subdirectories VI libraries or mnu files within the directory These palettes automatically update if you add new files to or
600. use while the user was interacting with the front panel of this VI This can be significant for some kinds of operations such as zooming in or out of a graph 26 4 National Instruments Corporation Chapter 26 Performance Issues selecting items from a pop up menu or selecting and typing text in a control e Locals Time spent copying data to or from local variables on the diagram Experience with users has shown that this time can sometimes be significant especially when it involves large complex data Memory Information When the Memory Usage checkbox is checked remember that this is only available if the Profile Memory Usage checkbox was selected before you began the profiling session you can view information about how your VIs are using memory These values are a measure of the memory used by the data space for the VI and do not include the support data structures necessary for all VIs The data space for the VI contains not just the data explicitly being used by front panel controls but also temporary buffers that are implicitly created by the compiler The memory sizes are measured at the conclusion of the run of a VI and might not exactly reflect its total usage For instance if a VI creates large arrays during its run but reduces their size before the VI finishes the sizes displayed do not reflect the intermediate larger sizes Two sets of data are displayed in this section data related to the number of bytes used
601. user you must make sure your palettes are changed to Basic G Select Edit Select Palette Set Then choose the Basic G palette from the palette set menu You create objects on the front panel and block diagram by selecting them from the floating Controls and Functions palettes For example National Instruments Corporation 2 1 G Programming Reference Manual Chapter 2 Building Vis if you want to create a knob on a front panel select it from the Numeric palette of the Controls palette as shown in the following illustration _ HNumeric Knob ac 1 0 100 W 0 1 z 1 st os fs AE dd oo io oo dh oo Wolo ole ania a 10 0 Co sO a oor As you move the selection arrow over an object on the palette the name of the object appears at the top of the palette In the preceding illustration the digital control is selected At this point if you click on and move the mouse over the front panel a digital control appears at the point where you release the mouse You can resize an object at the same time you create it by clicking on and dragging it as you place it iz Note If you need several functions from the same palette you can keep it open To keep a palette open select the pushpin in the top left corner of the palette When you have pinned the palette open it has a titlebar so you can move it around easily If you save the VI the next time you launch your G development environment the palettes are opened in t
602. ut the compiler reuses the input buffer This saves memory and also results in faster execution because no memory allocation needs to take place at run time The compiler cannot reuse memory buffers in all cases however as shown in the following illustration replace array element O A single source of data is being passed to multiple destinations The destinations want to modify the data to produce resulting arrays In this case the compiler creates new data buffers for two of the functions and copies the array data into the buffers Thus one of the functions is reused by the input array and the others are not This diagram uses about 12 KB 4 KB for the original array and 4 KB for each of the extra two data buffers National Instruments Corporation 26 15 G Programming Reference Manual Chapter 26 Performance Issues Now examine the following diagram Index Arra As before the input branches to three functions are the same However in this case none of them need to modify the data If you pass data to multiple locations all of which read the data without modifying it G does not need to make a copy of the data This diagram uses up about 4 KB of data Finally consider the following diagram replace array element O In this case the input branches to two functions one of which wants to modify the data There is no dependency between the two functions Therefore you can predict that at least one copy needs
603. ution With the execution system you can run multiple VIs simultaneously In addition within a given VI you might have several parallel branches each of which can also execute simultaneously In normal use you do not need to be concerned with the details of how multitasking takes place You can think of portions of a diagram as executing in parallel and multiple VIs as running in parallel With the execution system multitasking capability you can edit a VI while others run or you can single step through a VI while others run at full speed Also if you inadvertently build a VI with an infinite loop it should not lock up the computer or prevent other VIs from executing In some applications such as process control applications you might need a better understanding of how the multitasking system works The following section covers this topic Multitasking Most computers have only one processor meaning only one task can execute at any given time Multitasking is achieved by running one task for a short amount of time and then having other tasks run As long as the amount of time that each task has is small enough you have the appearance of having multiple tasks running simultaneously There are two kinds of multitasking preemptive and cooperative With a preemptive multitasking system each task is given a limited amount of time to execute When the time is up for a given task one task is forced to pause while another starts exec
604. ution Preemptive multitasking is not currently available on all operating systems and is not used currently by the execution system Cooperative multitasking which is more common in current small computer operating systems relies on each task being written to share time Each task is responsible for deciding when it should relinquish National Instruments Corporation 24 1 G Programming Reference Manual Chapter 24 Understanding the G Execution System Cooperation time to other tasks If any task fails to share time that task ends up locking out other tasks until it is ready to share time The execution system is a cooperative multitasking system which means it can execute multiple tasks in parallel Because it is cooperative you have no assurances that a given task executes within a specific amount of time Some nodes in G are synchronous meaning they do not multitask a complete list of these nodes is given in the Synchronous Nodes section later in this chapter If any synchronous nodes execute a lengthy process other tasks temporarily might be locked out of execution In practice this rarely causes problems because the number of synchronous nodes is relatively limited and the actions they execute generally take only a small amount of time When the compiler compiles a diagram into machine code the code is generated so that it periodically checks to see whether there are any other pending tasks and if it is time to have other
605. ution speed than if you can transfer data using an alternative wire path Global Variables Always Keep Copies of Their Data When you read from a global variable you create a copy of the data that is stored in that global variable When manipulating large arrays and strings the time and memory needed to manipulate global variables can be considerable This is especially inefficient when dealing with arrays if you only want to modify a single array element then store the entire array If you read from the global variable in several places in your diagram you might end up creating several buffers of memory One technique for minimizing memory usage in this case is to use an uninitialized shift register in a subVI This technique can combine the compactness of a global variable with the efficiency of a shift register Understanding When Memory Is Deallocated Consider the following diagram After the Mean VI has executed the array of data is no longer needed Because determining when data is no longer needed can become very complicated in larger diagrams the execution does not deallocate the data buffers of a particular VI during its execution National Instruments Corporation 26 21 G Programming Reference Manual Chapter 26 Performance Issues If the execution system is low on memory it deallocates data buffers used by any VI that is not currently executing The execution system does not deallocate memory used b
606. values to one of its indicators without halting execution The error condition exists only when a subVI attempts to return such a value Also an operator can enter out of range values into a control while its VI is executing The out of range error condition only prevents the VI from starting not from continuing once it already has started Debugging Executable Vis If your program executes but does not produce the expected results you often can solve the problem by taking the following steps e Eliminate all VI warnings If you select the Show Warnings option in the Error List window the listbox identifies the warnings for your VI Then you can determine the causes and eliminate them from your VI e Check wire paths to ensure that the wires connect to the proper terminals Triple clicking on the wire with the Operating tool highlights the entire path A wire that appears to emanate from one terminal actually might emanate from another so look closely to see where the end of the wire connects to the node e Use the Help window Help Show Help to make sure that both functions and Tip strips are wired correctly e Verify that the default value for functions or subVIs that have unwired inputs is what you expect e Use breakpoints execution highlighting and single stepping to determine if the VI is executing as you planned Make sure you disable these modes when you do not want them to interfere with performance e Use the probe
607. w option listbox controls pop up menu adding symbols to listbox items 13 4 suboptions 13 4 Show Parts Window option 22 7 Show Radix command 9 4 Show Selection option 11 9 14 14 14 16 Show submenu option 8 3 Show Terminals option 16 1 16 9 Show Toolbar option 6 6 G Programming Reference Manual I 50 Show VI Hierarchy option Hierarchy Node Pop Up menu 3 20 3 21 Project menu 3 15 Show VI Info command 2 27 Show Warnings option 4 10 signed and unsigned integer representation byte 8 bit 9 4 long 32 bit 9 4 word 16 bit 9 4 Simple Help option 1 7 single numeric data storage format A 2 single precision representation 32 bit SGL 9 4 single stepping through VIs 4 18 to 4 20 example 4 19 to 4 20 executing VIs 4 18 to 4 19 execution highlighting 4 21 to 4 23 Pause button 4 18 reading call chains 4 21 Step Into button 4 20 Step Out button 4 20 Step Over button 4 18 4 20 using step buttons 4 20 sink terminals 16 1 Size option Font ring 2 17 Size to Screen option 6 5 Size to Text option 2 23 16 4 Skip to beginning button 4 30 slide numeric controls and indicators 9 12 to 9 20 filled and multivalued slides 9 20 illustration 9 12 operating sliders 9 13 overview 9 12 scale markers 9 15 to 9 18 Arbitrary Markers mode 9 17 changing scale limits 9 16 deleting arbitrary marker 9 16 to 9 18 moving arbitrary markers 9 17 selecting non uniform scale marker distribution 9 16 to 9 18 Un
608. ware and Software Configuration Form Record the settings and revisions of your hardware and software on the line to the right of each item Complete a new copy of this form each time you revise your software or hardware configuration and use this form as a reference for your current configuration Completing this form accurately before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently National Instruments Products DAQ hardware Interrupt level of hardware DMA channels of hardware Base I O address of hardware Programming choice National Instruments software version s Other boards in system Base I O address of other boards DMA channels of other boards Interrupt level of other boards Other Products Computer make and model Microprocessor Clock frequency or speed Type of video board installed Operating system version Operating system mode Programming language Programming language version Other boards in system Base I O address of other boards DMA channels of other boards Interrupt level of other boards Documentation Comment Form National Instruments encourages you to comment on the documentation supplied with our products This information helps us provide quality products to meet your needs Title Edition Date Part Number G Programming Reference Manual Oct
609. well as individual relative time components can be increased and decreased To increase a digital display by a digit other than the ones digit use the Operating tool to place the insertion point to the right of the target digit When you are finished the ones digit again becomes the increment digit Numbers might become too large to fit in the digital display on the control You can view the complete value by resizing the control increasing its length horizontally Digital Numeric Options You can change the defaults for digital numerics through their pop up menus The pop up menu for a digital numeric is shown in the following illustration Change to Indicator Find Terminal SHOW Data Operations Create Key Navigation Replace Representation Data Range Format amp Precision National Instruments Corporation 9 3 G Programming Reference Manual Chapter 9 Numeric Controls and Indicators Displaying Integers in Other Radixes You can display signed or unsigned integer data in hexadecimal octal and binary form in addition to decimal form To change the form select Show Radix from the numeric pop up menu A d appears on the housing of the numeric display as shown in the following illustration digital contral Pex mebal Pinas If you click on the d the menu shown in the previous illustration appears The number 32 753 is displayed in each radix in the following illustration digital control
610. witched between horizontal and vertical display through an option in the View menu or by pressing the Horizontal Layout or Vertical Layout button at the top of the window In a horizontal display subVIs are shown to the right of their calling VIs in a vertical display they are shown below their calling VIs National Instruments Corporation 3 15 G Programming Reference Manual Chapter 3 Building SubVis SubVIs always are connected with lines to their calling VIs The window shown in the following illustration is displayed horizontally Al READ WAE Al START me Arrow buttons and arrows beside nodes indicate what is displayed and what is hidden as follows e A red arrow button pointing towards the node indicates that some or all subVIs are hidden Clicking on the button shows the immediate subVIs of the node e A black arrow button pointing towards the subVIs of the node indicates that all immediate subVIs are shown e A blue arrow pointing towards the callers of the node indicates that the node has additional callers that are not shown If a node has no subVIs no red or black arrow buttons are shown G Programming Reference Manual 3 16 National Instruments Corporation Chapter 3 Building SubVis A node becomes the focus node indicated by being surrounded by a thick red border when an operation is performed on it It becomes defocused when you perform an action on another node As you move your cursor ov
611. y front panel controls indicators global variables or uninitialized shift registers Now consider the same VI described previously as a subVI to a larger VI The array of data is created and used only in the subVI If the subVI is not executing and the system is low on memory it might deallocate the data in the subVI This is a case in which using subVIs can save on memory usage Determining When Outputs Can Reuse Input Buffers If an output is the same size and data type as an input and the input is not needed elsewhere the output can reuse the input buffer As mentioned previously in some cases even when an input is used elsewhere the compiler and the execution system can order code execution in such a way that it can reuse the input for an output buffer however the rules for this are complex and should not be counted on Consistent Data Types If an input has a different data type from an output the output cannot reuse that input For example if you add a 32 bit integer to a 16 bit integer you see a coercion dot that indicates that the 16 bit integer is being converted to a 32 bit integer The 32 bit integer input can be usable for the output buffer assuming it meets all of the other requirements for example the 32 bit integer is not being reused somewhere else In addition coercion dots for subVIs and many functions imply a conversion of data types In general the compiler creates a new buffer for the converted data
612. y of clusters assuming the cluster contains only scalars In the following diagram manipulation of elements becomes a little more complicated because you now have to use Unbundle and Bundle However because the cluster is probably small scalars use very little memory there is no significant overhead involved in accessing the cluster elements and replacing the elements back into the original cluster National Instruments Corporation 26 29 G Programming Reference Manual Chapter 26 Performance Issues If you have an array of clusters where each cluster contains large sub arrays or strings indexing and changing the values of elements in the cluster can be more expensive in terms of memory and speed When you index an element in the overall array a copy of that element is made Thus a copy of the cluster and its corresponding large subarray or string is made Because strings and arrays are of variable size the copy process can involve memory allocation calls to make a string or subarray of the appropriate size in addition to the overhead to actually copy the data of a string or subarray This might not be significant if you only plan to do it a few times However if your application centers around accessing this data structure frequently the memory and execution overhead might add up quickly The solution is to look at alternative representations for your data The following three case studies present three different applicatio
613. y resizes the panel of a VI to fit the screen when the VI is switched to run mode and when it is loaded into memory The VI does not retain a record of its original size and location so it stays in the same place if you switch back to edit mode Auto Center automatically centers the front panel on the user s computer screen when the VI is opened or when it is switched to run mode National Instruments Corporation 6 5 G Programming Reference Manual Chapter 6 Setting up Vis and SubVIs Other options toggle between showing and hiding various window features You can hide individual buttons by deselecting them or hide the entire toolbar by deselecting the Show Toolbar option Enable Log Print at Completion enables or disables automatic data logging see the Data Logging on the Front Panel section in Chapter 4 Executing and Debugging VIs and SubVIs and programmatic printing see the Programmatic Printing section in Chapter 5 Printing VIs Caution If you hide the menu bar and the toolbar there is no visible means of Wy changing from run mode back into edit mode Use the lt Ctr1 m gt Windows lt command m gt Macintosh lt meta m gt Sun or lt Alt m gt HP UX hot key that corresponds to the Operate Change to Edit Mode option to change the VI back to edit mode where the menu bar and palette are visible The options do not take effect until the VI starts running SubVI Node Setup Dialog Box The following dialog box
614. you want it click on the enter button to set it and exit the cluster order edit mode Click on the X button to revert to the old order The cluster order determines the order in which the elements appear as terminals on the Bundle and Unbundle functions in the block diagram For more information on these functions see the Online Reference Function and VI Reference String Functions topic Moving or Resizing Clusters Cluster elements are not permanent components of clusters That is you can move or resize elements independently even when they are in the shell To avoid inadvertently dragging them out click on the shell when you want to move a cluster and resize clusters from the shell border If you inadvertently drag an element when you meant to drag the whole cluster you can cancel the operation by dragging the element back into the shell or past the front panel window border before releasing the mouse button You also cancel a resizing operation by dragging the border past the front panel window before releasing the mouse button G Programming Reference Manual 14 22 National Instruments Corporation Chapter 14 Array and Cluster Controls and Indicators You can shrink clusters to fit their contents by selecting Autosizing from the pop up menu shown in the following illustration Change to Indicator Find Terminal Show gt Data Operations gt Create gt Key Navigation Replace gt Cluster Order Autosizing
615. your front panel contains more than 28 controls and indicators that you want to use programmatically group some of them into a cluster and assign the cluster to a terminal on the connector Required Recommended and Optional Connections for SubVIs G has a feature that can keep you from forgetting to wire subVI connections indications of required recommended and optional connections in the connector pane and the same indications in the Help window Inputs and outputs of VIs that come in vi 1ib have been premarked as Required Recommended or Optional G sets inputs and outputs of VIs that you create to Recommended by default When an input is marked as Required you cannot run the VI as a subVI without wiring it correctly When an input or output is marked as recommended you can run the VI but the Error List window lists a warning if warnings are enabled To see if connections are Required Recommended or Optional or to mark them as one of these states click on a terminal in the connector pane and select an option from the This Connection Is submenu A checkmark indicates its status as shown in the following illustration G Programming Reference Manual 3 8 National Instruments Corporation Chapter 3 Building SubVis Vl Setup Edit Icon Show Icon Patterns Rotate 90 Degrees Flip Horizontal Flip Vertical Disconnect All Terminals Disconnect This Terminal This Connection Is gt
616. your front panel extensively such as coloring and resizing it you might not want this automatic update feature You can pop up on the type definition on your front panel and turn off the Auto Update from Type Def option Instead of automatically updating this type definition when necessary the VI has a broken run arrow and the type definition on the front panel is disabled You cannot run the VI until you fix the type definition either by selecting the option Update from Type Def from the pop up menu or by changing the data type to match the type definition When you use a type definition you can assign a different default value to it However if the data type of the type definition changes all default data is updated from the master copy If the data type does not change the individual default values can be preserved National Instruments Corporation 22 21 G Programming Reference Manual Chapter 22 Custom Controls and Type Definitions Searching for Type Definitions Because G must keep a connection to the type definition the file or VI library containing the type definition must be available to runa VI using it If you open a VI and if a type definition that the VI needs is not found the type definition control on the front panel is disabled and the run arrow is broken To fix this problem you must either find and open the correct type definition or pop up on the disabled control and select Disconnect From Type Def Disconn
617. ze of an array control or indicator select Data Operations Show Last Element from the index array pop up menu National Instruments Corporation 14 13 G Programming Reference Manual Chapter 14 Array and Cluster Controls and Indicators Moving or Resizing Arrays Always move the array by clicking on the shell border or the index display and then dragging it If you drag the element in the array it separates from the array because the shell and elements are not locked together If you inadvertently drag the element when you meant to drag the shell cancel the operation by dragging the element back into the shell or past the front panel window border before releasing the mouse button You also cancel a resizing operation by dragging the border past the front panel window before releasing the mouse button If the array is part of the current selection then grabbing an element drags the array You can resize the array index vertically from any corner or horizontally from the left Selecting Array Cells You can copy data from and paste data to arrays by taking these steps 1 To select the data set the array index to the first element in the data set you want to copy 2 Then select the Data Operations Start Selection option from the array pop up menu 3 Next set the array index to the last element in the data set you want to copy 4 Finally select the Data Operations End Selection option from the array pop up menu

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