Home

Labview - Department of Materials Science and Metallurgy

1. t Youcan also select Probe tool from Tools palette el and click on wire When your VI is not executable a broken arrow is displayed in the Run button in the palette Finding Errors To list errors click on the broken arrow To locate the bad object click on the error message Execution Highlighting Animates the diagram and traces the flow of the data allowing you to view intermediate values Click on the light bulb on the toolbar Probe Used to view values in arrays and clusters Click on wires with the Probe tool or right click on the wire to set probes Retain Wire Values Used in conjunction with probes to view the values from the last iteration of the program Breakpoint Set pauses at different locations on the diagram Click on wires or objects with the Breakpoint tool to set breakpoints Exercise 1 Complete the following steps to create a VI that acquires data from your sound card 1 Launch LabVIEW 2 In the Getting Started window click the Blank VI link 3 Display the block diagram by pressing lt Ctrl E gt or selecting Window Show Block Diagram 4 Place the Acquire Sound Express VI on the block diagram Right click to open the functions palette and select Express Input Acquire Sound Place the Express VI on the block diagram 5 In the configuration window under Channels select 1 from the drop down list and click OK 6 Place the Filter Express VI to the right of the Acquire Signal VI
2. There is no set answer on how to approach writing a program however there are some useful tips Before you start ask yourself What do you actually want you program to do What inputs do you have to get you to this event How do you combine the inputs to get the desired output Once you have answered these questions you can start the process of writing the program This is generally an iterative process it is often useful though not always the case to start with a simple solution and add addition functions rather than try to do everything at once It is also important you document your work as you go this will help you if you have to come back to it at a later point or if anyone else has to work with your program The general process can be outlined as Define the problem Plan your solution Code the program Test the program A eae Document the program Program Elements Loops While Loop While Loops terminal counts iteration Always runs at least once Runs until stop condition is met For Loops i Jterminal counts iterations Run according to Input nJof count terminal 6 While and For Loops Both the While and For Loops are located on the Functions Structures palette The For Loop differs from the While Loop in that the For Loop executes a set number of times A While Loop stops executing the subdiagram only if the value at the conditional terminal exists While Loops Simil
3. In this exercise you should find a suitable model to convert the voltage to the pressure and use this to produce a program that can display an incoming voltage into a pressure You will be provided with a VI that will simulate a voltage output How should this pressure best be presented Can you include a high low pressure alarm What other features might be useful Assessed Exercise B Sound Analysis Write a program that listens for a particular sound breaking glass is not safe in the lab but what about a particular object hitting the bench and then raises an alarm Can you arrange for the program to let the sample sound be changed programmatically Can this program be extended to listen to someone speaking a specific word and by analyzing the tonal content of their voice recognize them Ideally your program will be able to tell the difference between two or three different people and programmatically learn new voices Can you extend your program to perform different actions in response to different sooken commands Assessed Exercise C Vision tracking Automatic person tracking software is a well developed technology which allows security cameras to track a person as they move across the field of view However they involve complex algorithms and do not work well in low light The aim of this project is to use a light source as an indicator of a person and use this to track their movement You have been provided with the following items
4. A stepper motor and controller A webcam 3 light sensors A NI DAQ box By using these devices it should be possible to scan across a room detect an intruder and acquire an image of them This image should then be saved for future reference Figure Pirani 501 recorder output graph mbar Stepper Motor The stepper motor is of the unipolar type and is provided with a drive board You do not need to worry about the exact mode of operation of the motor simply plug it into the drive board The board needs a 12V power supply with which you are provided The white striped wire is ve and the other ve At the back of this handout is the data sheet for the control board you can use to wire it correctly The drive board has a number of TTL level inputs you are probably most interested in those that control direction and step the level of the direction input controls the direction of the motor and every pulse sent to the step input will cause the stepper motor to move one step Using the counter on the DAQ unit you will be able to send the stepper motor a series of pulses that will cause it to move The stepper motor moves 1 8 degree per pulse you can set the driver board to half step mode which will cause the motor to move half that per pulse You can use the Driver EN input to shut down the driver when the motor is not needed to save power Remember that you will need to connect the digital ground on the DAQ board to the
5. Local Variables allow data to be passed between parallel loops single control or indicator can be read or written to from more than one location in the program Local Variables break the dataflow paradigm and should be used sparingly visible Items Find Control Loop 1 Hide Control Change to Indicator Change to Constant Description and Tip Numeric Palette Create Constant Data Operations Control Advanced Indicator oop Control Representation gt Local Variable AF Reference Men 6s Icon Property Node gt Properties Invoke Mode P Local variables are located in the Structures subpalette of the Functions palette When you place a local variable on the diagram it contains by default the name owned label of the first object you placed on the front panel You use a local variable by first selecting the object you want to access You can either click on the local variable with the Operating tool and select the object by owned label you want to access or pop up on the local variable and choose the object from the Select Item menu Next you must decide to either read or write to the object Right click on the local variable and choose Change To Read or Change to Write Further Help LabVIEW has a very comprehensive help system You should use it Remember that you can also right click on any vi to see its wiring diagam Exercise 6 Manual Analysis 1 Create a VI that displ
6. 400 000 measurements a second ots Device Input Range 10V 305uV The finite resolution of the measurements means there is an error associated with the digitisation a state of the art A D converter will run at 2 5 GS s digitized quantization noise analogue error due to jitter quantization levels time gt sampling gt jpe sampled sampled too late ton carly Nyquist Theorm Nyquist Theorem Sampling rate f s gt 2 highest frequency component of interest in the measured signal The Nyquist theorem states that a signal must be sampled at a rate greater than twice the highest frequency component of interest in the signal to capture the highest frequency component of interest otherwise the high frequency content will alias at a frequency inside the spectrum of interest pass band rr A Sampled atf B sampled at 2f TTL and CMOS Transistor transistor logic TTL is a class of digital circuits built from transistors and resistors Voc Vec Vour O collector O gt emitter GND The transistor transistor logic TTL family was developed in the use of transistor switches for logical operations and defines the binary values as 0 V to 0 8 V logic O 2Vto5V logic 1 The maximum rise fall time is 50 ns between VL and VH Time Specification Rise Time Fall Time 3 0 V 24V 2 0V Undefined em OV 0 4v OV Ground and ground loops ht
7. Boolean Numeric Arrays Strings Clusters and more The color and symbol of each terminal indicate the data type of the control or indicator Control terminals have a thicker border than indicator terminals Also arrows appear on front panel terminals to indicate whether the terminal is a control or an indicator An arrow appears on the right if the terminal is a control and an arrow appears on the left if the terminal is an indicator Definitions Array Arrays group data elements of the same type An array consists of elements and dimensions Elements are the data that make up the array A dimension is the length height or depth of an array 31 An array can have one or more dimensions and as many as 2 1 elements per dimension memory permitting Cluster Clusters group data elements of mixed types such as a bundle of wires in a telephone cable where each wire in the cable represents a different element of the cluster See Help Search the LabVIEW Help for more information The LabVIEW User Manual on ni com provides additional reference for data types found in LabVIEW Debugging Techniques e Finding Errors ES Click on broken Run button Window showing error appears e Execution Highlighting A Click on Execution Highlighting button data flow is animated using bubbles Values are displayed on wires Probes Bis Right clickon wire to display probe and It shows Numeric data as It flows through wire segment
8. Cluster subpalette select the Array icon Controls RealMatrix ctl me Drop it on the Front Panel ComplexMatri Error In 3D ctl Error Out 3D ctl Aray D gt System 1p Classic gt Express gt NET amp Activex Select a Control 12 An Array Control To create an array control or indicator as shown select an array on the Controls Modern Array Matrix and Cluster palette place it on the front panel and drag a control or indicator into the array shell If you attempt to drag an invalid control or indicator such as an XY graph into the array shell you are unable to drop the control or indicator in the array shell You must insert an object in the array shell before you use the array on the block diagram Otherwise the array terminal appears black with an empty bracket Create an Array Step 2 of 2 1 Place an Array Shell 13 Creating an Array To add dimensions to an array one at a time right click the index display and select Add Dimension from the shortcut menu You also can use the Positioning tool to resize the index display until you have as many dimensions as you want Timing a loop 1 Loop Time Delay e Configure the Time Delay Express VI for seconds to wait each iteration of the loop works on For and While loops 2 Timed Loops e Configure special timed While loop for desired df Time Delay Timed Loop Time Delay The Time Delay
9. The input value determines which box to execute If out of range of the cases LabVIEW will choose the default case Example c When the Boolean passes a TRUE value to the Select VI the value 5 is passed to the indicator When the Boolean passes a FALSE value to the Select VI O is passed to the indicator Shift Registers Available at left or right border of loop structures Right click the border and select Add Shift Register Right terminal stores data on completion of iteration Left terminal provides stored data at beginning of next iteration A values Before Loop First Second Last Begins Iteration Iteration Iteration Shift registers transfer data from one iteration to the next Right click on the left or right side of a For Loop or a While Loop and select Add Shift Register The right terminal stores data at the end of an iteration Data appears at the left terminal at the start of the next iteration A shift register adapts to any data type wired into it An input of O would result in an output of 5 the first iteration 10 the second iteration and 15 the third iteration Said another way shift registers are used to retain values from one iteration to the next They are valuable for many applications that have memory or feedback between states State Machines eWhile Loop eCase Structure eShift Register o State bossssssssesssessssosesssesesso Tranation A ba gs cn Code S 2 oge 3 2 E
10. Vig sin w t Osig The lock in amplifier then generates its own internal reference phase locked to an external refer ence Reference V sin w t 8 et The lock in amplifies the signal and then multiplies it by the lock in reference using a phase sensitive detector or multiplier The output of the PSD is simply the product of two sine waves Vesp VigVi sin w t 0jg sin w t 6 cf VsigV L cos w w t Oig Oret h VsigWL cos w w t Osig Oret The PSD output is two AC signals one at the difference frequency w w and the other at the sum frequency w W If the PSD output is passed through a low pass filter the AC signals are removed If w equals w the difference frequency component will be a DC signal In this case the filtered PSD output will be Vosd Y VeigVi COS Bsig Oret This is a very nice DC signal proportional to the signal amplitude Note the later sections of each exercise are challenging and open ended do not be dispirited if your program does not work very well the important thing is to show you can program in Labview and understand and explain in your report the limitations of your program Assessed Exercise A Pressure sensor A pirani is a widely used tool to measure vacuum pressures The pirani consists of a metal wire the resistance of which varies with pressure This variation is calibrated and gives a voltage output in relation to the pressure as shown in the figure on the next page
11. EII OOOO ee You can use the state machine design pattern to implement an algorithm that you can explicitly described with a state diagram or flowchart A state machine consists of a set of states and a transition function that maps to the next state Each state can lead to one or multiple states or end the process flow A common application of State machines is to create user interfaces In a user interface different user actions send the user interface into different processing segments Each processing segment acts as a state Process testing is another common application of the state machine design pattern For a process test a state represents each segment of the process Depending on the result of each state s test a different state might be called Start Default_ pf Several programming techniques exist for transitioning from state to state in LabVIEVV using State Machines Default transition implies that after one state another state always follows Transitions between two potential states can be handled by a Select Function Review of datatypes Double Precision Humber Waveform Cluster Integer Humber Complex Humber Error Cluster Y 20 Array of Doubles Simulate Signal Matrix of Doubles ri 0 a Jprecrseorscrcescecsescerneaacerneeacectaeacee r1 F 9 Type of data in LabVIEW LabVIEW utilizes many common datatypes These Datatypes include
12. Labview Vis can be saved to disk just like any other document Please don t forget to save a copy of your work to a USB stick or other safe place so you don t lose it Saving different versions can be useful in case you decide you want to revert to an earlier version of your programme File Operate Tools Help fa LabVIEW 2013 Cl Create Project Open Existing Show All 2 Blank Project Power Control vproj Front Panel Data Socket Ivproj Shared Variable lvproj IV Curve Ivproj Paralell loops Ivproj Temperature Monitoring Iwproj ho Find Drivers and Add ons he Community and Support he Welcome to LabVIEW Connect to devices and expand the E Participate in the discussion forums or Leam to use LabVIEW and upgrade functionality of LabVIEW request technical support from previous versions LabVIEW News Interact With LabVIEW From Your Tablet LabVIEW Basics LabVIEW programs are called virtual instruments VIs Controls are inputs and indicators are outputs Each VI contains two main parts Front Panel How the user interacts with the VI 139 slide Example v1 File Edit View Project Operate Tools Window Block Diagram The code that controls the program 13 Slide Example vi Block Diagram Ja Eg File Edit View Project Operate Tools Window Help ESOO ASIS In LabVIEW you build a user interface by using a set of tools and objects The user interface is known as the front panel You then
13. close it Spreadsheet Vis Sometimes it is better to save data as text so you can import it into Excel Soreadsheets are usually ASCII text files with a certain type of formatting Two formatting methods are comma separated values CSV and tab delimited Tab delimited files which are the most popular have tabs constants between columns of data and end of line constants between rows LabVIEW includes VIs that perform this formatting e Write to Spreadsheet File takes either 1D or 2D arrays of numeric data formats this data and writes this information to file e Format Into File takes many different types of data string numeric Boolean and writes this information to file using either a file path or file reference This function can be resized to include as many data terminals as necessary e Array to Spreadsheet String is a string function that formats array data into a string that can be written to a text file e The Concatenate String function is used to create longer strings from shorter ones and is the most flexible when converting data to a string that can be written to a text file Exercise 5 Spreadsheet Vis not all wiring instructions are given here some are obvious refer to the diagram or ask a demonstrator if you are unsure 1 Open a blank new VI from the Getting Started screen 2 Place the Open Create Replace File function on the block diagram Right click on the block diagram to open the functions pa
14. devices are sharing an earth within a building it is likely the poten tial will fluctuate Therefore it is often preferable to have a clean or isolated earth Using an isola tion transformer allows you to have a second circuit with its own very good connection to earth such that you can be confident it is constant you can also bias this reference to an arbitrary value if required Using a transformer to pass power from the main supply prevents high frequency noise Power Source Load BI T Lock in amplifiers http www thinksrs com downloads PDFs ApplicationNotes AboutLIAs pdf Lock in amplifiers allow you to measure very small signals buried in large amounts several orders of magnitude larger of background signal noise By exciting the experiment at a known frequency the lock in can act as a very narrow band pass filter which then extracts only the signal you require In essence a lock in amplifier takes the input signal multiplies it by the reference signal either provided from the internal oscillator or an external source and integrates it over a specified time usually on the order of milliseconds to a few seconds The resulting signal is a DC signal where the contribution from any signal that is not at the same frequency as the reference signal is attenuated close to zero Reference Signal 7 O ref Lock in Firstly a signal is created by exciting the experiment using an external sine wave Signal
15. drop it Put other constants inside the shell Note You cannot place terminals for front panel objects in a cluster constant on the block diagram nor can you place special constants like the Tab or Empty String constant within a block diagram cluster shell Cluster Functions Inthe Cluster amp Variant subpalette of the Programming palette e Can also be accessed by right clicking the cluster terminal umeric contra oro Pa pl 3 EINEN component ees me Cluster component 1 ez Terminal labels Et reflect data type Bundle input cluster new component A owned label 4 J new component B owned label B output cluster Bundle By Name The terms Bundle and Cluster are closely related in LabVIEW Example You use a Bundle Function to create a Cluster You use an Unbundle function to extract the parts of a cluster Bundle function Forms a cluster containing the given objects explain the example Bundle by Name function Updates specific cluster object values the object must have an owned label Note You must have an existing cluster wired into the middle terminal of the function to use Bundle By Name Using Arrays and Clusters with Graphs Waveform Graph Plot 0 i The Waveform Datatype contains 3 pieces of data etO Start Time edt Time between Samples e Y Array of Y magnitudes Two ways to create a Waveform Cluster Build Wa
16. ground on the driver board for the signals to be read Light Sensors The Light Sensors have 3 wires 5V Red OV black and output Configure the analog input for differential mode where each channel measures the voltage between two inputs You will need to connect the light sensor to the 5V output of the DAQ board and to the Digital Ground The output needs to go to the terminal of one of the analog inputs Remember that you will need to connect the ve input to the digital ground terminal in order to measure the output from the light sensor The data sheet for the light sensor is at the back of this handout It has a non linear response closely matched to that of the human eye and will output about 4 2V in bright light The Light Sensor has been pre wired for you with a 5 1 kQ resistor USB Camera Using the LabVIEW Vision Development module you will be able to simply build a VI that takes a picture from the camera The system is much more powerful than this and you may wish to spend some time exploring the features of the software If you get stuck ask a demonstrator DAQ Pinout The counter outputs by default on PFI4 Do not address the output lines as a port since this will prevent you using PFI4 as a counter output address the output lines individual in labview Bus Powered M Series Multifunction DAQ for USB 16 Bit up to 400 kS s up to 32 Analog Inputs Isolation a USS crn A a Mw Pub i z wet Wee Up to 32
17. gt CDB2D ray gt 2D Array gt U16 1D Matrix gt U32 1D U64 1D 18 1D 116 1D 132 1D 164 1D y DBL 1D EXT 1D CSG 1D CDB 1D CXT 1D Boolean 1D String 1D Properties String 1D 13 Wire Out to the Waveform Graph 14 Return to the front panel and increase the frequency to be between 50 and 100 Run the VI 15 Open the Interactive MathScript Window Tools MathScript Window 16 In the MathScript Window the Command Window can be used to enter in the command that you wish to compute In the Command Window type global In and press Enter This will allow you to see the data passed to the variable In on the MathScript Node 17 Note that all declared variables in the script along with their dimensions and type are listed on the Variables tab To display the graphed data click once on the variable In and change the drop down menu from Numeric to Graph 18 Use the graph palette to zoom in on your data 19 Multiply the data by a decreasing exponential function Follow these steps a Make a 100 element array of data that constitutes a ramp function going from 0 01 to 5 by typing Array 0 01 0 05 5 in the Command Window and pressing Enter What type of variable is Array b Make an array containing a decreasing exponential Type Exp 5 exp Array and press Enter C Now multiply the Exp and In arrays element by element by typing Out In Exp and pres
18. is very useful when trying to track down bugs Strings Strings are pieces of text data which can be manipulated just like any other data type A primary use is for file names where certain tasks are often useful String Length Returns in length the number of characters bytes in string Array To Spreadsheet String Converts an array of any dimension to a table in string form containing tabs separating column elements a platform dependent EOL character separating rows and for arrays of three or more dimensions headers separating pages Concatenate Strings Concatenates input strings and 1D arrays of strings into a single output string For array inputs this function concatenates each element of the array Match Pattern Searches for regular expression in string beginning at offset and if it finds a match splits string into three substrings A regular expression requires a specific combination of characters for pattern matching Dialog Boxes The Dialog and User Interface group features a number of VIs which allow the user to make decisions Popup boxes can be useful when setting up the VI for the first time but use them with care too many can be very frustrating Paths Paths are a specific type of string which carry file location data You can ask a user to select a file location using a dialog box or you can use a number of preset file locations such as the correct My Documents folder or the location where the VI
19. itself is saved There are type categories of file path relative and absolute A relative path describes the location of a file or directory relative to an arbitrary location in the file system An absolute path describes the location of a file or directory starting from the top level of the file system Using relative paths in VIs avoids having to rework the paths if you build an application or run the VI ona different computer Digital vs analog TTL sampling rates and Nyquist theory We will be using a NI USB 6211 16 Bit 250 kS s M Series Multifunction DAQ But what does this mean The Data Aquistion box DAQ has 4 key features e Upto 32 analog inputs at 16 bits up to 400 kS s 250 kS s scanning e Upto 2 analog outputs at 16 bits e Upto 32 TTL CMOS digital I O lines e Two 32 bit 80 MHz counter timers Analog to digital conversion The DAQ box can measure analog inputs however in order to process this using a digital system a computer this analog signal must be digitised This is where the 16 bits up to 400 kS s is important To digitise an analog signal is is broken down into a number of discrete values digitzation levels or bins The number of these levels defines the resolution in terms of the measurement value in this case 16 bit This means there are 2 of these levels 65 536 The next important value is how quickly the input value is quantised this determines the resolution in time The NI USB 6211 can make
20. 6 Colors at iia C Show Terminals TT Disconnect All Terminals C x LJ 256 Colors aan aan ha 8 Right click on the Connector Panel and select Edit Icon This will bring up the Icon Editor 9 Modify the graphics to more accurately represent the function of the SubVI in this case Addition 10 Save the SubVI It can now be used in any other VI to perform any function in this case adding two numbers Advanced Labview Concepts We will now explore some more involved aspects of working with Labview Many of these will be important if you want your program to run on multiple machines or be used by other people The details given here are only an overview where applicable there is a link to further information Property nodes Many of the variables normally controlled through the settings dialog boxes can also be controlled programmatically using property nodes Visual elements like colours and labels can be changed but it is also possible to query front panel objects in ways not normally possible A ocale Range Maximum m A Scale Range Minimum s Active Plot waa Waveform Graph ee 7 Color Box bx Scale Maximum XScale Minimum Plot Color ActPlot Plot Mame Plot Plot Mame To create a property node right click on the object you wish to control then Create Property Node Diagram Disable This tool found in the structures panel allows you to temporarily disable areas of code This
21. Express VI delays execution by a specified number of seconds Following the rules of Data Flow Programming the while loop will not iterate until all tasks inside of it are complete thus delaying each iteration of the loop Timed Loops Executes each iteration of the loop at the period you specify Use the Timed Loop when you want to develop VIs with multi rate timing capabilities precise timing feedback on loop execution timing characteristics that change dynamically or several levels of execution priority Double click the Input Node or right click the Input Node and select Configure Timed Loop from the shortcut menu to display the Loop Configuration dialog box where you can configure the Timed Loop The values you enter in the Loop Configuration dialog box appear as options in the Input Node Wait Until Next ms Multiple Waits until the value of the millisecond timer becomes a multiple of the specified millisecond multiple Use this function to synchronize activities You can call this function in a loop to control the loop execution rate However it is possible that the first loop period might be short This function makes asynchronous system calls but the nodes themselves function synchronously Therefore it does not complete execution until the specified time has elapsed Functions Programming Timing Wait Until Next ms Multiple A 14 The Wait until Next ms Multiple function Clusters Clusters group like or unlike compon
22. Natural Sciences Tripos Part II MATERIALS SCIENCE Computing Course LabVIEW NATIONAL INSTRUMENTS Dr D Bosworth Michaelmas Term 2015 16 UNIVERSITY OF CAMBRIDGE Department of Materials Bronze Award Science and Metallurgy Computerised Data Acquisition in LabVIEW Dr D Bosworth October 2015 This course is adapted from LabVIEW in 6 hours published by National Instruments and a range of NI white papers Where relevant links have been included to provide more detail Introduction LabVIEW is one of several programming languages that can be used to automate scientific experiments It is widely used in the materials science department because it can be used to write programs quickly that have easy to use graphical interfaces This course will cover the basics of how to use labview and then provide a chance for you to put what you have learnt in to practice Course Overview The course consists of 6 hours of introductory lectures and 12 hours of practical work We expect to you to have widely different programming experience please do not worry if you find that some tasks take you longer than other members of the group There are a total of 3 assessed exercises which you should aim to complete through the term The course is assessed out of 30 marks You will work individually for the first two assessed exercises and as a pair for the final one The final report must be entirely your own work A max
23. add code using graphical representations of functions to control the front panel objects The block diagram contains this code In some ways the block diagram resembles a flowchart Users interact with the Front Panel when the program is running Users can control the program change inputs and see data updated in real time Controls are used for inputs such as adjusting a slide control to set an alarm value turning a switch on or off or to stop a program Indicators are used as outputs Thermometers lights and other indicators display output values from the program These may include data program states and other information Every front panel control or indicator has a corresponding terminal on the block diagram When a VI is run values from controls flow through the block diagram where they are used in the functions on the diagram and the results are passed into other functions or indicators through wires Use the Controls palette to place controls and indicators on the front panel The Controls palette is available only on the front panel To view the palette select Window Show Controls Palette You also can display the Controls palette by right clicking an open area on the front panel Tack down the Controls palette by clicking the pushpin on the top left corner of the palette EJ Modern system Classic i ww F Express EP ei b b J 4 H all I i Mum Ctrls Buttons Text Ctrls Al H ej m Mum I
24. al Measurements Express VI Functions Express Signal Analysis Spectral 5 Find the dominant frequency of the filtered data using the Tone Measurements Express VI 6 Compare that frequency to a user inputted limit If the frequency is over that limit light up an LED 7 If you get stuck ask the demonstrator for a hint Exercise 9 Creating a SubVI A Create a subVI from a new VI which adds two inputs and outputs the sum 2 Open a new VI Ctrl N 3 Place the Add function Programming Numeric on the block diagram 4 Create controls and indicators by right clicking and selecting Create Control or Indictor The Block Diagram and Front Panel should look similar to the images below 5 On the Front Panel right click the Icon at the top right and select Show Connector to reveal the Connector Pane 6 Assign icon terminals to the two controls and indicators by first left clicking on a icon terminal and then clicking the desired control indicator al 7 Note General convention is to have controls as data inputs on the left side and indicators as outputs on the rights side of this icon VI Properties Edit Icon Show Icon Find All Instances Icon Editor File Edit Help Add Terminal TT Remove Terminal B amp w Copy from Bae Patterns gt ee _Black amp white _ pS Rotate 90 Degrees __ 16 Colors BZ Flip Horizontal IN oe color
25. ally when input is open depending on the switch position CLOCK DIS functions are logic LOW active LS TTL level 0 V to lt 0 8 V no HIGH signal allowed leave open instead CCW HS functions are logic LOW active LS TTL level 0 V to lt 0 8 V CLOCK one step is generated for each negative edge of the clock signal clock signal LS TTL level Take care on the input levels LS TTL signals For LOW a real ground connection is required If an input is left open it is detected as HIGH Input signals gt 5V may destroy the SAMOTRONIC101 SAMOtronic101_R7_E doc 1 5 rgess OU 35 sala Smart solutions for comfort and safety 40 Saia Burgess Dresden AG Karl Liebknecht Strasse 6 D 01257 Dresden Germany T 49 0 351 207 860 F 49 0 351 207 863 61 www Saia burgess com field of operation unipolar stepper motors lt 350 mA phase power supply 10 24 10 VDC connectors plug connector for the motor screw connector for supplying voltage and external control signals Functions Logic level LS TTL LOW OV to lt 0 8V HIGH gt 2V to 5V function external setting on the PCB variable via screw connector connector step frequency S1 On adjustable via on use port CLK to access the board potentiometer internal generated clock signal fs 50 20 390 Hz 10 accuracy 15 CLOCK S1 Off connect to external clock TTL via shielded cable full step mode S2 Off half step m
26. analog inputs at 16 bits up to 400 kS s 250 NI PGIA 2 and NI MCal calibration technology for kS s scanning improved measurement accuracy Up to 2 analog outputs at 16 bits NI signal streaming for 4 high speed data streams Up to 32 TTL CMOS digital I O lines on USB Two 32 bit 80 MHz counter timers Bus powered design Available with CAT isolation Overview With recent bandwidth improvements and new innovations from National Instruments USB has evolved into a core bus of choice for measurement and automation applications NI M Series devices for USB deliver high performance data acquisition in an easy to use and portable form factor through USB ports on laptop computers and other portable computing platforms National Instruments designed the new and innovative patent pending NI signal streaming technology that enables sustained bidirectional high speed data streams on USB The new technology combined with advanced external synchronization and isolation helps engineers and scientists achieve high performance applications on USB NI M Series bus powered multifunction data acquisition DAQ devices for USB are optimized for superior accuracy in a small form factor They provide an onboard NI PGIA 2 amplifier designed for fast settling times at high scanning rates ensuring 16 bit accuracy even when measuring all available channels at maximum speed All bus powered devices have a minimum of 16 analog inputs digital triggering and two counter ti
27. ar to a Do Loop or a Repeat Until Loop in text based programming languages a While Loop shown at the top right executes a subdiagram until a condition is met The While Loop executes the sub diagram until the conditional terminal an input terminal receives a specific Boolean value The default behavior and appearance of the conditional terminal is Stop If True When a conditional terminal is Stop If True the While Loop executes its subdiagram until the conditional terminal receives a TRUE value The iteration terminal an output terminal shown at left contains the number of completed iterations The iteration count always starts at zero During the first iteration the iteration terminal returns 0 For Loops A For Loop shown above executes a subdiagram a set number of times The value in the count terminal an input terminal represented by the N indicates how many times to repeat the subdiagram The iteration terminal an output terminal shown at left contains the number of completed iterations The iteration count always starts at zero During the first iteration the iteration terminal returns O Drawing a Loop 2 Enclose code to be repeated 1 Select the structure While Loop Flat Sequence Case Structure e Time Delay Elapsed Time gt Favorites Select a VI 7 Drawing a Loop Place loops in your diagram by selecting them from the Structures palette of the Functions palette When selected the mo
28. ays simulated data on a waveform graph and measures the frequency and amplitude of that data Use cursors on the graph to verify the frequency and amplitude measurements 2 Open Exercise 3 3 Save the VI as Exercise 6 vi 4 Go to the block diagram and remove the While Loop Right click the edge of the loop and choose Remove While Loop so that the code inside the loop does not get deleted 5 Delete the stop button 6 Make the cursor legend viewable on the graph Right click on the graph and select Visible Items Cursor Legend 7 Change the maximum value of the Frequency In dial to 100 Double click on the maximum value and type 100 once the text is highlighted 8 Set a default value for the Frequency In dial by setting the dial to the value you would like right clicking the dial and selecting Data Operations Make Current Value Default 9 Run the VI and observe the signal on the waveform graph If you cannot see the signal you may need to turn on auto scaling for the x axis Right click on the graph and select X Scale AutoScale X 10 Change the frequency of the signal so you can see a few periods on the graph 11 Manually measure the frequency and amplitude of the signal on the graph using cursors To make the cursors display on the graph click on one of the three buttons in the cursor legend Once the cursors are displayed you can drag them around on the graph and their coordinates will be display
29. cify the file name file format and segment size These functions are very easy to use and are excellent for simple applications In the case where you will do constant streaming to the files by continuously writing to or reading from the file there may be some overhead in using these functions In the next example we will examine how to write to or read from LabVIEW Measurements files lvm files Arrays Building arrays with Loops Loops can accumulate Auto Indexing Enabled arrays at their boundaries re ACONES MENO with auto indexing For Loops auto index by default While Loops output only the final value by default e Right click tunnel and Auto Indexing Disabled enable disable auto indexing 1D Array Indicator 012345 Wire remains the same size Numeric Indicator Only one value last iteration 5 is passed out of the loop 11 How to auto index arrays For Loops and While Loops can index and accumulate arrays at their boundaries This is known as auto indexing The indexing point on the boundary is called a tunnel The For Loop default is auto indexing enabled e The While Loop default is auto indexing disabled Examples Enable auto indexing to collect values within the loop and build the array All values are placed in array upon exiting loop Disable auto indexing if you are interested only in the final value Creating an Array Control From the Controls Modern Array Matrix and
30. clocks External base clock frequency Base clock accuracy 2 32 bits Edge counting pulse semi period period two edge separation 80 MHz 20 MHz 0 1 MHz 0 MHz to 20 MHz 50 ppm Stepping Motor Tech nical k Type Y129 Informat 422 8 023 Phase resistance Phase inductance MA TO Holding torque bipolar Nem ls TA AAA Detent torque Nem Jg 28 gt 9 an Rotor inertia gem 2 PB fInsulationClass B Single All dimensions in mm i amp TRO gt Y Ni ADVANCING THE DRIVETOWARDS MOTOR EFFICIENCY Issue 01 01 03 Saia Burgess Dresden AG Karl Liebknecht Strasse 6 D 01257 Dresden Germany T 49 0 351 207 860 F 49 0 351 207 863 61 www Saia burgess com SAMOTRONIC101 4 636 6608 0 Short Reference Unipolar Stepper Motor Driver 1 Overview All dimensions in mm Tolerance of hole diameter 0 1mm of all other dimensions 0 5mm ll 55 10VDC 24VDC CLOCK DIS CLOCK CW CCW FS HS DRIVER INH OOVOOO p 41 10 Frequency driver inibit connect DRIVER INH input with GND to let the motor run full step mode external frequency LS TTL OFF PhA1 PhA PhA2 ON PhB1 PhB internal frequency PhB2 half step mode motor is working as long as the SAMOTRONIC101 is connected to the supplying voltage CW FS DRIVER INH functions are logic HIGH active LS TTL level gt 2 V to 5 V they apply automatic
31. dd Input Name this input In1 by typing while the input node is highlighted black 7 Right click on the right border of the MathScript Node and select Add Output Name this output Out 8 Convert the Dynamic Data Type output of the Simulate Signals VI to a 1D Array of Scalars to input to the MathScript Node Place a Convert from Dynamic Data Express VI on the block diagram Express Signal Manipulation Convert from Dynamic Data By default the VI is configured correctly so click OK in the configuration window 9 Wire the Sine output of the Simulate Signal VI to the Dynamic Data input of the Convert from Dynamic Data VI 10 Wire the Array output of the Convert from Dynamic Data VI to the In1 node on the MathScript Node 11 In order to use the data from the Simulate Signal VI in the Interactive MathScript Window it is necessary to declare a global variable and then place the value from In1 in it Inside the MathScript Node type global In and on the next line In In1 Initally we will just pass this variable straight through so type Out In 12 Right click on the variable Out and select Choose Data Type All types 1D Array DBL 1D Output data types must be set manually on the MathScript Node global In 2 In In1 3 Out In Waveform Graph gr i Change to Input Remove Choose Data Type gt Array Palette gt All Types gt Scalar gt reate
32. did a a ERE T a y e f T Cadmium free sensor with spectral response The Through hole Type for easy implementation as Light Sensor NaPiCa Le a CdS cell replacement FEATURES 1 Built in optical filter for spectral response similar to that of the human eye Peak sensitivity wavelength is 580 nm Through hole lype TYPICAL APPLICATIONS 1 Brightness detection for LCD backlight control for LCD devices LCD TVs car navigation systems etc 2 Brightness detection for circuits in a Human spectral household lighting crime y NE NaPiCa spectral prevention lighting and automatic Fa a ik 4 lighting for bicycle a oh ie 3 Brightness detection for wall clocks 2 A IN radio clocks pen E po 4 Brightness detection for z X MEA surveillance cameras night O O IA switching MO NIA ot oN Anode 400 50 500 600 700 800 900 1000 1100 Cathode Wavelength nm 2 Photocurrent is proportional to illumination linear output High photocurrent is achieved by built in photocurrent amp IL 260 uA typical Ev 100 Ix florescent light 3 Uses environmentally friendly silicon chips 4 Lead free 5 Operates on 1 5 to 6 V DC which is suitable for battery operation 6 Same through hole shape as CdS cell TYPES Photocurrent Packing quantity 260 pA 2 000pes Note Ev 100 lx Fluorescent lamp is used as light source Tape package is the standard pack
33. e Between Front Panel and Block Diagram lt Ctrl Z gt Undo Also in Edit Menu Tools Options Set Preferences In LabVIEW VI Properties Configure VI Appearance Documentation etc 4 Keyboard Shortcuts LabVIEW has many keystroke shortcuts that make working easier The most common shortcuts are listed above While the Automatic Selection Tool is great for choosing the tool you would like to use in LabVIEW there are sometimes cases when you want manual control Once the Automatic Selection Tool is turned off use the Tab key to toggle between the four most common tools Operate Value Position Size Select Edit Text Set Color on Front Panel and Operate Value Position Size Select Edit Text Connect Wire on Block Diagram Once you are finished with the tool you choose you can press lt Shift Tab gt to turn the Automatic Selection Tool back on In the Tools Options dialog there are many configurable options for customizing your Front Panel Block Diagram Colors Printing and much more Similar to the LabVIEW Options you can configure VI specific properties by going to File VI Properties There you can document the VI change the appearance of the window and customize it in several other ways There are several buttons available across the top of the program window Run Button Continuous Run Button Additional Buttons on the Diagram Toolbar Abort Execution Pause Continue Button pt A
34. e Labeling tool to edit text and create free labels The Labeling tool changes to a cursor when you create free labels Scrolling Tool Breakpoint Tool Probe Tool Color Copy Tool 214 Coloring Tool 3 Shortcut Menu Tool Use the Wiring tool to wire objects together on the block diagram The Context Help function is a quick way of finding out more about a sub VI Pressing Ctrl H will bring up the window when you hover over a VI it will display the information about it Context Help To get helpful information about a node move the cursor onto it Objects with context help information include Vis functions constants structures palettes properties methods events and dialog box components To display the Context Help window select Help Show Context Help press the lt Ctrl H gt keys or press the Show Context Help Window button in the toolbar Connections displayed in Context Help Required bold Recommended normal Optional dimmed Additional Help VI Function amp How To Help is also available Help VI Function amp How To Help Right click the VI icon and choose Help or Choose Detailed Help on the context help window LabVIEW Help reference style help Help Search the LabVIEW Help e Keystroke Shortcuts lt Ctrl H gt Activate Deactivate Context Help Window lt Ctrl B gt Remove Broken Wires From Block Diagram lt Ctri E gt Toggl
35. e sure substitute copy for original is selected and click Continue 4 Add a case structure to the block diagram inside the while loop Functions Programming Structures Case Structure 5 Inside the true case of the case structure add a Write to Measurement File Express VI Functions Programming File O Write to Measurement File write To Measurement File a In the configuration window that opens choose Save to series of files multiple files Note the default location your file will be saved to and change it if you wish b Click Settings and choose Use next available file name under the Existing Files heading C Under File Termination choose to start a new file after 10 segments Click OK twice 6 Add code so that if the frequency computed from the Tone Measurements Express VI goes below a user controlled limit the data will be saved to file Hint Go to Functions Programming Comparison Less 7 Remember to connect your data from the DAQ Assistant or Acquire Sound Express VI to the Signals input of the Write to Measurement File VI If you need help refer to the solution to this exercise 8 Go to the front panel and run your VI Vary your frequency limit and then stop the VI 9 Navigate to My Documents LabVIEW Data and open one of the files that was saved there Examine the file structure and check to verify that 10 segments are in the file 10 Save your VI and
36. earch the LabVIEW Help SubVIs for more information LabVIEW Functions and SubVls operate like Functions in other languages Function Pseudo Code Calling Program Pseudo Code function average in1 in2 out main out in1 in2 2 0 average in1 in2 pointavg SubVI Block Diagram Calling VI Block Diagram A subVI node corresponds to a subroutine call in text based programming languages The node is not the subVI itself just as a subroutine call statement in a program is not the subroutine itself A block diagram that contains several identical subVI nodes calls the same subVI several times The modular approach makes applications easier to debug and maintain The functionality of the subVI does not matter for this example The important point is the passing of two numeric inputs and one numeric output Icon and Connector Pane m 1 Use this connector pane layout as a standard aii Top terminals are usually reserved for references such as a file reference Bottom terminals are usually reserved for Inputs Outputs error clusters Reference In Reference Out The Icon and Connector Pane allows you to define the data being transferred in and out of the subVI as well as its appearance in the main LabVIEW code Every VI displays an icon in the upper right corner of the front panel and block diagram windows After you build a VI build the icon and the connector pane so you can use the VI as a subVI T
37. ect on the Front Panel a terminal will be created on the Block Diagram These terminals give you access to the Front Panel objects from the Block Diagram code Each terminal contains useful information about the Front Panel object it corresponds to For example the color and symbols provide information about the data type For example The dynamic data type is a polymorphic data type represented by dark blue terminals Boolean terminals are green with TF lettering In general blue terminals should wire to blue terminals green to green and so on This is not a hard and fast rule LabVIEW will allow a user to connect a blue terminal dynamic data to an orange terminal fractional value for example But in most cases look for a match in colors A red dot indicates that values are being converted from one variable type to another Controls have an arrow on the right side and have a thick border Indicators have an arrow on the left and a thin border Logic rules apply to wiring in LabVIEW Each wire must have one but only one source or control and each wire may have multiple destinations or indicators Dataflow Programming Block diagram execution Dependent on the flow of data Block diagram does NOT execute left to right Node executes when data Is available to ALL input terminals Nodes supply data to all output terminals when done LabVIEW follows a dataflow model for running VIs A block diagram node execut
38. ed in the cursor legend If you can t see the cursor check they aren t at the far edge of the plot window Cursors X Y a 3 Visible Items H Create Cursor P Free Single Plot Multi Plot Properties 12 Remember that the frequency of a signal is the reciprocal of its period f 1 T Does your measurement match the frequency and amplitude indicators from the Tone Measurements VI 13 Save your VI and close it 14 If you are making good progress try to see if you can programmatically calculate the frequency from the cursors Hint you will need to create a property node on the graph indicator for the cursors and select each of two cursors in turn Exercise 7 MathScript Note that in Mathscript the input to the formula node cannot be a global variable Make sure that you wire the input to In1 and then define a global variable and place the value of In1 in it di Create a VI that uses the MathScript Node to alter your simulated signal and graph it Use the Interactive MathScript Window to view and alter the data and then load the script you have created back into the MathScript Node 2 Open Exercise 6 vi 3 Save the Vl as Exercise 7 vi 4 Go to the block diagram and delete the wire connecting the Simulate Signal VI to the Waveform Graph 5 Place down a MathScript Node Programming Structures MathScript Node 6 Right click on the left border of the MathScript Node and select A
39. ents together They are equivalent to a record in Pascal or a struct in C Cluster components may be of different data types Examples Error information Grouping a Boolean error flag a numeric error code and an error source string to specify the exact error User information Grouping a string indicating a user s name and an ID number specifying their security code All elements of a cluster must be either controls or indicators You cannot have a string control and a Boolean indicator Clusters can be thought of as grouping individual wires data objects together into a cable cluster Creating a Cluster 1 Select a Cluster shell 2 Place objects inside the shell Controls Modern Array Matrix Cluster Fuser theses a Cluster front panel objects can be created by choosing Cluster from the Controls Modern Array Matrix amp Cluster palette This option gives you a shell similar to the array shell when creating arrays You can size the cluster shell when you drop it Right click inside the shell and add objects of any type Note You can even have a cluster inside of a cluster The cluster becomes a control or an indicator cluster based on the first object you place inside the cluster You can also create a cluster constant on the block diagram by choosing Cluster Constant from the Cluster palette This gives you an empty cluster shell You can size the cluster when you
40. es when all its inputs are available When a node completes execution it supplies data to its output terminals and passes the output data to the next node in the dataflow path Visual Basic C JAVA and most other text based programming languages follow a control flow model of program execution In control flow the sequential order of program elements determines the execution order of a program Consider the block diagram above It adds two numbers and then multiplies by 2 from the result of the addition In this case the block diagram executes from left to right not because the objects are placed in that order but because one of the inputs of the Multiply function is not valid until the Add function has finished executing and passed the data to the Multiply function Remember that a node executes only when data are available at all of its input terminals and it supplies data to its output terminals only when it finishes execution In the second piece of code the Simulate Signal Express VI receives input from the controls and passes its result to the Graph You may consider the add multiply and the simulate signal code to co exist on the same block diagram in parallel This means that they will both begin executing at the same time and run independent of one another If the computer running this code had multiple processors these two pieces of code could run independent of one another each on its own processor without any additional coding
41. he control on the front panel the label text is highlighted While this text is highlighted type Frequency In to give a name to this control You will need to edit this control so it gives a range from 10 100 as the Simulate Signal VI only works with frequencies above 10Hz 5 Go to the block diagram lt Ctrl E gt and place a while loop down Right click to open the functions palette and select Express Execution Control While Loop Click and drag on the block diagram to make the while loop the correct size Select the waveform chart and dial and drag them inside the while loop if they are not already Notice that a stop button is already connected to the conditional terminal of the while loop 6 Place the Simulate Signal Express VI on the block diagram From the functions palette select Express Signal Analysis Simulate Signal and place it on the block diagram inside the while loop In the configuration window under Timing choose Simulate acquisition timing Click OK Simulate Signal 7 Place a Tone Measurements Express VI on the block diagram Express Signal Analysis Tone Measurements In the configuration window choose Amplitude and Frequency measurements in the Single Tone Measurements section Click OK Tone Measurements 8 Make the following connections on the block diagram by hovering your mouse over the terminal so that it becomes the wiring tool and clicking once on each of the terminals y
42. he exact same functionality and if needed the temperature scale selection portion of the code can be reused in other applications very easily Any portion of LabVIEW code can be turned into a subVI that in turn can be used by other LabVIEW code Creating SubVIs A subVI node corresponds to a subroutine call in text based programming languages A block diagram that contains several identical subVI nodes calls the same subVI several times The subVI controls and indicators receive data from and return data to the block diagram of the calling VI Click the Select a VI icon or text on the Functions palette navigate to and double click a VI and place the VI on a block diagram to create a subVI call to that VI A subVI input and output terminals and the icon can be easily customized Follow the instructions below to quickly create a subVI eEnclose area to be converted into a subVl eSelect Edit Create SubVI from the Edit Menu Creating SubVIs from Sections of a VI Convert a section of a VI into a subVI by using the Positioning tool to select the section of the block diagram you want to reuse and selecting Edit Create SubVI An icon for the new subVI replaces the selected section of the block diagram LabVIEW creates controls and indicators for the new subVI automatically configures the connector pane based on the number of control and indicator terminals you selected and wires the subVI to the existing wires See Help S
43. he icon and connector pane correspond to the function prototype in text based programming languages There are many options for the connector pane but some general standards are specified above Namely to always reserve the top terminals for references and the bottom terminals for error clusters To define a connector pane right click the icon in the upper right corner of the front panel and select Show Connector from the shortcut menu Each rectangle on the connector pane represents a terminal Use the terminals to assign inputs and outputs Select a different pattern by right clicking the connector pane and selecting Patterns from the shortcut menu An icon is a graphical representation of a VI If you use a VI as a subVI the icon identifies the subVI on the block diagram of the VI The Icon Editor is a utility that comes built into LabVIEW 8 to allow users to fully customize the appearance of their subVls This allows programmers to visually distinguish their subVIs which will greatly improve the usability of the subVI in large portions of code After you ve defined the connector pane and have customized the icon you are ready to place the subVI into other LabVIEW code There are two ways to accomplish this To place a subVI on the block diagram 1 Click the Select a VI button on the Functions palette 2 Navigate to the VI you want to use as a subVI 3 Double click to place it on the block diagram To place an open VI on the block diagra
44. imum of 5 marks are awarded for each of the first two exercises with 10 marks available for the final exercise You will be marked on how well your final programs fulfils the specifications the quality of the solution you have arrived at and how well you have used the various aspects of labview to complete the problem 10 marks will be awarded for a short report on the three programs no more than 8 A4 pages This should explain how your programs work why you made your design choices and assess how well you think your final effort fulfilled your aims The deadline for the submission of the report will be given to you at the start of the term A paper copy should be submitted to the teaching office You should also combine the VIS from your project into a zip file and email this to teaching office msm cam ac uk You should find you have your own computer in the computer lab and a microphone is provided this will serve as a source of data Work through the exercises in this booklet in order LabVIEW LabVIEW opens as an application like any other When you open the program choose to create a New blank VI Virtual Instrument or VI is the term that National Instruments applies to an individual program or subroutine When your new program opens there are two windows The grey coloured window is the Front Panel from where you interact with the program The white coloured window is the program where you draw your program
45. ing style RATINGS 1 Absolute maximum ratings Ambient temperature 25 C 77 F Item Symbol AMS302 Remarks Reverse voltage VR 0 5 to 8 V Photocurrent IL 5 mA Power dissipation P 40 mA Operating temperature Topr 30 to 85 C 22 to 185 F Non condensing at low temperatures Storage temperature Tstg 40 to 100 C 40 to 176 F Non condensing at low temperatures 2 Recommended operating condition ued ZAL AMS302 Remarks Reverse voltage Stein y 1 5 V 3 Maximum 6V All Rights Reserved COPYRIGHT Matsushita Electric Works Ltd Light Sensor AMS3 3 Electrical characteristics Ambient temperature 25 C 77 F ltem Symbol AMS302 Condition Peak sensitivity wavelength Ap 580 nm Minimum 9 1uA Photocurrent 1 Typical lu 13uA Vr 5V Ev 5 lx Maximum 16 9uA Minimum 182uA Photocurrent 2 Typical lla 26014 A Vr 5 V Ev 100 Ix Maximum 338uA Photocurrent 3 Typical lus 500uA Vr 5 V Ev 100 Ix Dark current Maximum lo 0 3uA Vr 5V o ee pica eas Va 2 5 V Vo 2 5 V Ri 5kQ Fall time Typical tr 8 5 ms 1 Fluorescent lamp is used as light source Substituted with white LED for testing before shipping 2 CIE standard illuminant A is used as light source Measuring method for switching time White LED gt REFERENCE DATA 1 Power dissipation vs ambient temperature 2 Relative sens
46. itivity vs wavelength 3 Dark current vs ambient temperature characteristics characteristics characteristics Ambient temperature 25 C 77 F Reverse voltage 5V 50 1 0 10 RN Human spectral gt MOB EN NaPiCa spectral E 40 gt 08 z E A E O O O O EL T Eo SI 5 MN 5 E e EA q qv _ AN O AAT T llo E A 1 oot HA TT tT 00 CEP ANV PU ot Le S rr ne a A 0 20 40 60 8085 100 400 500 600 700 800 900 1000 1100 Ambient temperature C Wavelength nm Ambient temperature C 4 Photocurrent vs brightness characteristics 5 Relative photocurrent vs ambient 6 Relative photocurrent vs reverse voltage Light source Fluorescent lamp CIE standard A temperature characteristics characteristics Reverse voltage 5V Ambient temperature 25 C 77 F Light source Fluorescent lamp Brightness 100 Ix Light source Fluorescent lamp Brightness 100 Ix Reverse voltage 5V Ambient temperature 25 C 77 F 10000 CIE standard A Amis 1000 E AMABA ee NH HH e Pt TA va iw CH ee CH AHHH Many E E AA PA Photocurrent uA Relative photocurrent Relative photocurrent 10 Cob dc EHH CE EE L PTET A 1 10 100 1000 10000 40 20 0 20 40 60 80 100 Brightness Ix Ambient temperature C Reverse voltage V All Rights Reserved COPYRIGHT Matsushita Electric Works Ltd
47. lect Numeric Random Number 0 1 12 Wire the error out terminal of the Write Text File function to an output tunnel on the While Loop 13 Place an Unbundle By Name function inside the While Loop Right click on the block diagram to open the functions palette and select Cluster amp Variant Unbundle By Name 14 Wire the error out from the Write Text File function to the Unbundle By Name function 15 Place an Or function in the While Loop Right click on the block diagram to open the functions palette and select Boolean Or 16 Switch to the front panel and place a stop button Right Click on the front panel to open the Controls palette and select Boolean Stop Button 17 On the block diagram wire the status element of the error cluster to the x input of the Or function and wire the stop button to the y input 18 Wire the output of the Or function to the conditional terminal of the While Loop 19 Place a Close File function to the right of the While Loop Right click on the block diagram to open the functions palette and select File I O Close File 20 Wire the refnum output tunnel to the refnum input terminal of the Close File function 21 Wire the error output tunnel to the error in terminal of the Close File function 22 Return to the front panel and run the VI You will be prompted to Choose or enter path of file to open enter spreadsheet xls 23 Click on the stop button to stop the executio
48. lette and select File I O Open Create Replace File 3 Right click the operation terminal of the Open Create Replace File function and select Create Constant from the shortcut menu and select open or create from the drop down menu 4 Place a While loop from the Structures palette on the block diagram to the right of the Open Create Replace File function Right click on the block diagram select Structures While Loop 5 Place a Write Text File function inside the While Loop Right click on the block diagram select File I O Write To Text File 6 Wire the refnum out terminal from the Open Create Replace File function to the file use dialog terminal of the Write Text File function 7 Wire the error out terminal from the Open Create Replace File function to the error in terminal of the Write Text File function 8 Place an Array to Spreadsheet String function inside the while loop and to the left of the on Open Create Replace File function Right click on the block diagram and select String Array to Spreadsheet String 9 Right click the format string terminal of the Array to Spreadsheet function and select Create Constant from the shortcut menu and enter 0 4f in the string constant to format the input data 10 Place a Build Array Function on the block diagram Right click on the block diagram and select Array Build Array 11 Place a Random Number inside the While Loop Right click on the block diagram and se
49. m is a tab delimited text file you can open with a spreadsheet application or a text editing application This file format is a specific type of ASCII file created for LabVIEW The lvm file contain information about the data such as the date and time the data was generated TDM This file format is a specific type of binary created for National Instruments products It actually consists of two separate files an XML section contains the data attributes and a binary file for the waveform High Level File I O These functions provide a higher level of abstraction to the user by opening and closing the file automatically before and after reading or writing data Some of these functions are e Write to Spreadsheet File Converts a 1D or 2D array of single precision numbers to a text string and writes the string to a new ASCII file or appends the string to an existing file e Read From Spreadsheet File Reads a specified number of lines or rows from a numeric text file beginning at a specified character offset and converts the data to a 2D single precision array of numbers The VI opens the file before reading from it and closes it afterwards e Write to Measurement File Express VI that writes data to a text based measurement file lvm or a binary measurement file tdm format e Read from Measurement File An Express VI that writes data to a text based measurement file lvm or a binary measurement file tdm format You can spe
50. m of another open VI 1 Use the Positioning tool to click the icon of the VI you want to use as a subVI 2 Drag the icon to the block diagram of the other VI Math nodes You can also enter mathematical equations in LabVIEW in so called MathScript windows You can place these from the structures window Finish each line with a semicolon top ensure that the windows only terminates when every line has processed MathScript Mode y put n 0 length fe x cost pi a r 10 A MathScript Node Help for the environment can be accessed using the Mathscript Interactive Environment Window Type Help in the command window for an introduction to MathScript help Help followed by a function will display help specific to that function File I O File I O operations pass data from memory to and from files In LabVIEW you can use File I O functions to o Open and close data files o Read data from and write data to files e Read from and write to spreadsheet formatted files o Move and rename files and directories Change file characteristics e Create modify and read a configuration file The different file formats that LabVIEW can use or create are the following Binary Binary files are the underlying file format of all other file formats ASCII An ASCII file is a specific type of binary file that is a standard used by most programs ASCII file are also called text files LVM The LabVIEW measurement data file lv
51. mers USB M Series devices are ideal for test control and design applications including portable data logging field monitoring embedded OEM in vehicle data acquisition and academic PFI OP0 0 In PFI 10 1 In PFI 2 P0 2 In PFI S P0 3 In D GND PFI 4 P 1 0 Out PFI SP 1 1 Out PFI amp P 1 2 Out PFI 7P1 3 Out bo Y D GND AC O AQ 1 AC ND Al Q Ala Al 1 AIS Al 2 Al 10 Al 3 Al 11 Al SENSE Al 4 Al 12 ALS Al 13 Al GND Al 6 Al 14 Al Al 15 EF LOG PEZ E pm ri da k k P E Lab pl di 2 a or k e Analog Input Number of channels Maximum Sampling rate Timing resolution Input coupling Input range Analog Output Number of channels DAC resolution Maximum update rate 1 channel 2 channels Timing accuracy Timing resolution Output range Output coupling Output impedance Output current drive Power on state Power on glitch Output FIFO size Data transfers 8 differential or 16 single ended 250 kS s single channel 250 kS s multichannel aggregate 50 ns DC 10 V 5 V 1 V 0 2V 10 4 V of Al GND 2 16 bits 250 kS s 250 kS s per channel 50 ppm of sample rate 50 ns 10 V DG 0 20 2 mA 20 mV 1 V for 200 ms 8 191 samples shared among channels used USB Signal Stream programmed I O General Purpose Counter Timers Number of counter timers Resolution Counter measurements Internal base
52. n of the VI 24 Open the file named spreadsheet xls 25 Save and the close the VI Switches One of the most basic control mechanisms is through switches However depending on how you want the switch to behave there are various mechanical options to choose from Action on Press or Release RELEASE PRESS RELEASE RELEASE How many times will LabVIEW read it Many times Many times Maybe never released too quick Maybe many times released slowly Once revert when LabVIEW reads Once revert when LabVIEW reads At least once maybe more revert when LabVIEW reads after button released Sub Vis Select f IED y i N as Mukipty Add DAQ Assistant gt Ez Convert repeated functions L and VIs with a single VI _ Modularity defines the degree to which your VI is composed of discrete components such that a change to one component has minimal impact on other components In LabVIEW these separate components are called subVIs Creating subVIs out of your code increases the readability and reusability of your VIs In the upper image we see repeated code allowing the user to choose between temperature scales Since this portion of this code is identical in both cases we can create a subVI for it This will make the code more readable by being less clustered and will allow us to reuse code easily As you can see the code is far less cluttered now achieves t
53. nds LEDs Text Inds a a Ln ee Graph Indicat P NET amp Active Select a Control 1 The Controls Palette Use the Functions palette to build the block diagram The Functions palette is available only on the block diagram To view the palette select Window Show Functions Palette You also can display the Functions palette by right clicking an open area on the block diagram Tack down the Functions palette by clicking the pushpin on the top left corner of the palette xe Ch Search Choa VIE Programming Instrument To Mathematics Signal Processing Data Communication Connectivity itr rr rrF F Express 7 Input Signal Analysis i 4 1 TF FL a Cc gm Cc LOT a WM Signal Manipu Exec Control Arith amp Compar Nl H Favorites Select a YI 2 The Functions Palette If automatic tool selection is enabled and you move the cursor over objects on the front panel or block diagram LabVIEW automatically selects the corresponding tool from the Tools palette Toggle automatic tool selection by clicking the Automatic Tool Selection button in the Tools palette ES 3 The Tools Palette Use the Operating tool to change the values of a control or select the text within a control Use the Positioning tool to select move or resize objects The Positioning tool changes shape when it moves over a corner of a resizable object Use th
54. ode S2 On switching between FS HS S2 Off HIGH or not connected full step full nalf step mode LOW half step stop signal S3 On motor is working with step frequency as long as supplying voltage appears DRIVER INH 2 Off LOW motor is working with step frequency HIGH or not connected motor stands still phases switched off CLK DIS LOW clock stopped motor still under current HIGH is not allowed direction CW CCW TTL signal 0 V CCW HIGH or not connected CW The single functions are fixable with help of the DIP switches or controllable with external signals With fixed functions it is only necessary to connect the SAMOTRONIC101 to the supplying voltage and to change the direction if necessary Mounting The unit must be installed in a case so that the user is not able to access it while working Otherwise and for maintenance purpose the unit must be used in an antistatic environment and the user must be discharged with standard ESD protection equipment Take care to leave minimum distance to holes and gapes in the case to prevent electrostatic discharges A typical value for 8kV EN50082 1 2 is 8mm DIN VDE0110 1 depending on environment humidity and temperature conditions Cables Max cable length for all control inputs screw terminal port 2 6 is 3m At the clock input screw terminal port 5 shielded wires must be used SAMOtronic101_R7_E doc 2 5 rgess OU Smart solutions for comfort and safety S
55. on the block diagram From the functions palette select Express Signal Analysis Filter and place it on the block diagram In the configuration window under Filtering Type choose Highpass Under Cutoff Frequency use a value of 300 Hz Click OK 7 Make the following connections on the block diagram by hovering your mouse over the terminal so that it becomes the wiring tool and clicking once on each of the terminals you wish to connect a Connect the Data output terminal of the Acquire Signal VI to the Signal input of the Filter VI b Create a graph indicator for the filtered signal by right clicking on the Filtered Signal output terminal and choose Create Graph Indicator 8 Return to the front panel by pressing lt Ctrl E gt or Window Show Front Panel 9 Run your program by clicking the run button Hum or whistle into your microphone and observe the data you acquire from your sound card 10 Save the VI 11 Close the VI Exercise 2 1 Create a VI that produces a sine wave with a specified frequency and displays the data on a Waveform Chart until stopped by the user 2 Open a blank VI from the Getting Started screen 3 Place a chart on the front panel Right click to open the controls palette and select Controls Modern Graph Waveform Chart 4 Place a dial control on the front panel From the controls palette select Controls Modern Numeric Dial Notice that when you first place t
56. ou wish to connect a Connect the Sine output terminal of the Simulate Signal VI to the Signals input of the Tone Measurements VI b Connect the Sine output to the Waveform Chart C Create indicators for the amplitude and frequency measurements by right clicking on each of the terminals of the Tone Measurements Express VI and selecting Create Numeric Indicator d Connect the Frequency In control to the Frequency terminal of the Simulate Signal VI 9 Return to the front panel and run the VI Move the Frequency In dial and observe the frequency of the signal Click the stop button once you are finished 10 Save the VI dd Close the VI Notes When you bring up the functions palette press the small push pin in the upper left hand corner of the palette This will tack down the palette so that it doesn t disappear This step will be omitted in the following exercises but should be repeated Exercise 3 1 Create a VI that measures the frequency and amplitude of the signal from your sound card and displays the acquired signal on a waveform chart The instructions are the same as in Exercise 2 but the Sound Signal VI is used in place of the Simulate Signal VI Try to do this without following the instructions 2 Open a blank VI 3 Go to the block diagram and place a While Loop down Express Execution Control While Loop 4 Place the Acquire Sound Express VI on the block diagram Ex
57. pplication Font Text Settings step Into Button Align Objects E Distribute Objects Y Step Over Button step Out Button p Reorder i Resize front panel objects 5 Buttons avaliable in a LabVIEW window Click the Run button to run the VI While the VI runs the Run button appears with a black arrow if the VI is a top level VI meaning it has no callers and therefore is not a subVl Click the Continuous Run button to run the VI until you abort or pause it You also can click the button again to disable continuous running While the VI runs the Abort Execution button appears Click this button to stop the VI immediately Note Avoid using the Abort Execution button to stop a VI Either let the VI complete its data flow or design a method to stop the VI programmatically By doing so the VI is at a known state For example place a button on the front panel that stops the VI when you click it Click the Pause button to pause a running VI When you click the Pause button LabVIEW highlights on the block diagram the location where you paused execution Click the Pause button again to continue running the VI Select the Text Settings pull down menu to change the font settings for the VI including size style and color Select the Align Objects pull down menu to align objects along axes including vertical top edge left and so on Select the Distribute Objects pull down menu to space objects evenly including gaps com
58. press Input Acquire Sound 5 Place a Filter Express VI on the block diagram In the configuration window choose a highpass filter and a cutoff frequency of 300 Hz 6 Place a Tone Measurements Express VI on the block diagram Express Signal Analysis Tone In the configuration window choose Amplitude and Frequency measurements in the Single Tone Measurements section 7 Create indicators for the amplitude and frequency measurements by right clicking on each of the terminals of the Tone Measurements Express VI and selecting Create Numeric Indicator 8 Connect the Data terminal of the Acquire Sound Express VI to the Signal input of the Filter VI 9 Connect the Filtered Signal terminal of the Filter VI to the Signals input of the Tone Measurements VI 10 Create a graph indicator for the Filtered Signal by right clicking on the Filtered Signa terminal and selecting Create Graph Indicator 11 Return to the front panel and run the VI Observe the signal from your sound card and its amplitude and frequency Hum or whistle into the microphone and observe the amplitude and frequency you are producing 12 Save the VI Close the VI Exercise 4 Decision Making and Saving Data 1 Create a VI that allows you to save your data to file if the frequency of your data goes below a user controlled limit 2 Open Exercise 3 3 Go to File Save As and save it In the Save As dialog box mak
59. pression and so on Select the Resize Objects pull down menu to change the width and height of front panel objects Select the Reorder pull down menu when you have objects that overlap each other and you want to define which one is in front or back of another Select one of the objects with the Positioning tool and then select from Move Forward Move Backward Move To Front and Move To Back Note The following items only appear on the block diagram toolbar Click the Highlight Execution button to see the flow of data through the block diagram Click the button again to disable execution highlighting Click Retain Wire Values button to save the wire values at each point in the flow of execution so that when you place a probe on a wire you can immediately obtain the most recent value of the data that passed through the wire Click the Step Into button to single step into a loop subVI and so on Single stepping through a VI steps through the VI node to node Each node blinks to denote when it is ready to execute By stepping into the node you are ready to single step inside the node Click the Step Over button to step over a loop subVI and so on By stepping over the node you execute the node without single stepping through the node Click the Step Out button to step out of a loop subVI and so on By stepping out of a node you complete single stepping through the node and go to the next node A simple VI When you create an obj
60. sing Enter Note the operator is the matrix multiplication operator and not the simple multiplication operator d Look at the graph of the variable Out 20 Go to the History tab and use Ctrl click to choose the 4 commands you just entered Copy those commands using lt Ctrl C gt 21 On the Script tab paste the commands into the Script Editor using lt Ctrl V gt 22 Save your script by clicking Save at the bottom of the window Save it as myscript txt 23 Close the MathScript Window 24 Return to the block diagram of Exercise 4 2 MathScript Load the script you just made by right clicking on the MathScript Node border and selecting Import Navigate to myscript txt select it and click OK 25 Return to the front panel and run the VI 26 Does the data look like you expect Can you edit the program so that it responds to a change in frequency in real time 27 Save and close your VI Show your VI to the demonstrator Exercise 8 1 In this exercise you will create a VI that uses what you have learned Design a VI that does the following 2 Acquire data from your device and graph it 3 Filter that data using the Filter Express VI Functions Express Signal Analysis Filter There should be a front panel control for a user configurable cut off frequency 4 Take a Fast Fourier Transform to get the frequency information from the filtered data and graph the result Use the Spectr
61. tp www ni com white paper 3394 en At a simple level ground or earth is the reference zero point from which voltages can be measured This common zero makes it possible to measure the differential voltage at different sites If a circuit is not connected to ground then it is referred to as floating Power supplies and any equipment connected through a main supply will typically be grounded to earth Self contained circuits like multimeters or circuits running from a battery will typically not reference earth and therefore are floating While ground can often be thought of as a perfect sink for charge in that it never has a voltage build up on it in reality for very sensitive measurements there can be problems with using a normal grounding The grounds of two independently grounded signal sources generally will not be at the same poten tial The difference in ground potential between two instruments connected to the same building ground system is typically 10mV to 200mV or even more The difference can be higher if power dis tribution circuits are not properly connected Signal Interconnection line Signal 0 1V Grounded Equipments Safety Ground Wire AC voltage caused by Resistance 0 1 ohm current in ground wire a 1 A current flowing Because there is voltage difference between the equipment the signal in the interconnection wire sees that difference added to signal Additionally if a large number of
62. use cursor becomes a special pointer that you use to enclose the section of code you want to repeat Click the mouse button to define the top left corner click the mouse button again at the bottom right corner and the While Loop boundary is created around the selected code Drag or drop additional nodes in the While Loop if needed 1 Case Structures NA a Boolean Control 8 Different ways of making a choice in LabVIEW Case Structure The Case Structure has one or more subdiagrams or cases exactly one of which executes when the structure executes The value wired to the selector terminal determines which case to execute and can be boolean string integer or enumerated type Right click the structure border to add or delete cases Use the Labeling tool to enter value s in the case selector label and configure the value s handled by each case It is found at Functions Programming Structures Case Structure Select Returns the value wired to the t input or f input depending on the value of s If s is TRUE this function returns the value wired to t If sis FALSE this function returns the value wired to f The connector pane displays the default data types for this polymorphic function It is found at Functions Programming Comparison Select Example a Boolean input Simple if then case If the Boolean input is TRUE the true case will execute otherwise the FALSE case will execute Example b Numeric input
63. veform absolute time Cluster relative time The waveform data type carries the data start time and At of a waveform You can create waveforms using the Build Waveform function Many of the Vis and functions you use to acquire or analyze waveforms accept and return the waveform data type by default When you wire a waveform data type to a waveform graph or chart the graph or chart automatically plots a waveform based on the data start time and Ax of the waveform When you wire an array of waveform data types to a waveform graph or chart the graph or chart automatically plots all the waveforms The feedback node is another representation of the same concept pictured below Both programs pictured behave the same Communicating between loops Communicating between loops using data flow is not possible The left loop will execute completely before the right loop Variables are needed when communication with wires does not give the desired behavior Loop 1 Loop 2 There is no way to communicate between parallel loops using data flow Data cannot enter or leave a structure while it s still running via dataflow Variables are block diagram elements that allow you to access or store data in another location Local variables store data in front panel controls and indicators Variables allow you to circumvent normal dataflow by passing data from one place to another without connecting the two places with a wire Local Variables

Labview - Department of Materials Science and Metallurgy

Contents

Download Pdf Manuals

Related Search

Related Contents