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1. Appendix To purchase the Khepera mobile robot to run the examples described in this manual order item number MLLV4 4 from K Team K Team SA Chemin de Vuasset CP 111 CH 1028 Pr verenges Switzerland http www k team com Phone 41 21 802 5472 Fax 41 21 802 54 71 Email info k team com Contact Francesco Mondada Index PathnameSeparator 52 202 Abelmann Leon 118 Abort 33 38 Abort vi 182 acquisition boards 5 AddControls 59 201 203 AddIndicators 59 201 203 advantage of MathLink over formula nodes 116 array 64 ASCII 3 26 Bad PrimeQ vi 34 Basic Front End vi 89 94 96 diagram 96 bin2Link vi 177 bitmap 92 93 Bolhuis Thijs 118 C See programming language CallIByReference 12 48 206 CallInstrument 12 56 61 206 process monitoring 107 CIN 13 63 Close All Links vi 47 56 183 Mathematica Link for LabVIEW ClosePanel 54 205 Close VIRef 205 cluster 61 64 Codes And Messages vi 87 183 coerce 66 color palette 93 Complex Application Example 117 Complex subdirectory 118 ConnectToServer 47 49 51 control 3 control character 52 57 Control2bin vi 177 cooperation level 27 Copyright Notice vi 71 106 183 custom palettes 124 data acquisition 5 8 data dependency 67 123 data flow 3 4 data structures 14 24 63 65 201 data types 37 38 63 66 cluster 61 conversion table 66 expected 14 32 polymorphi
2. Mathematica Link for LabVIEW Connected a Lil Open ii gt Lar ds Link monitoring requires two timing parameters to be integrated smoothly within an application A timeout is required to avoid getting trapped in an infinite loop Depending on the application and particular context you will want to choose between a finite or an infinite value for this parameter The other timing parameter is the link scanning period Since LabVIEW s diagrams are cooperative multitasking systems it is necessary to slow down all tasks that are not priorities The strategic use of the wait function allows the introduction of a hierarchy in task priorities refer to LabVIEW documentation for more information on this subject When monitoring a link it is necessary to balance the fast processing of incoming data with the overall CPU load Link Monitor vi The main structure of Link Monitor vi illustrated in Figure 16 is a while loop Three conditions can be used to exit the loop 1 MLReady returns 1 there is something ready to be read on the link 2 MLError does not equal MLEOK an error occurred on the link 3 Timeout exceeded 83 4 Programming Mathematica Link for LabVIEW Since these three conditions are not equivalent it is necessary to inform downstream VIs of a possible error This is the purpose of the Proceed indicator The link can be read only when this indicator returns True When an i
3. 4 Programming Mathematica Link for LabVIEW SIMPLE DATA SERVER VI DIAGRAM The Simple Data Server vi diagram has all the basic features necessary to establish a session and write data on a link First the link is opened and a connection is made Any errors that may have resulted from a previous sequence are processed at this stage to avoid sending data over a malformed link connection There is one main execution loop that terminates when the user presses the Stop button The only command lying outside of this main loop is MLC lose Inside the main loop is a nested user interface loop to poll user action When this inner UI loop terminates the data flow is directed to a case structure where a series of MathLink commands are executed in accordance with the user s choice Pay particular attention to the complex number transmission depicted in the figure Complex numbers are transmitted as functions because of their internal representation in Mathematica After the type specific case structure executes data are flushed using the MLFlush command and MathLink Error Manager vi processes any errors that may have occurred Simple Data Client vi The Simple Data Server vi demonstrates albeit in the simplest terms how to pass parameters from LabVIEW to Mathematica but suppose you prefer to move data in the other direction In this case you will be more interested in Simple Data Client vi We will explore Simple Data Client vi next OPERATI
4. OutputClusterTemplate ctl is an indicator cluster containing every kind of data that can be received from a link This indicator is used by MathLinkCIN vi and by all other Vis implementing MathLink functions Note however that it is hidden from the front panel of all Vis except MathLinkCIN vi Warning Integers are transmitted through the long integer field Output cluster In this cluster are collected all possible kinds of data that can be communicated to the CIN Not all are used together For a given MLFunction call only a limited set of data is used The other variables are passed but not used MLFunction The name of the MathLink function called Link out The link identifier Value The integer value returned by the function string The field used to read strings 135 5 Reference Guide MLFast lIb 136 long integer The field used to read integers of any format double The field used to read doubles long double The field used to read long doubles integer list The field used to read lists of integers long integer list The field used to read lists of long integers double list The field used to read lists of doubles long double list The field used to read lists of long doubles I gt HLF ast ls a a m Mathematica Link for LabVIEW Vis GetBoolean vi Link in Link out l boolean error in no error ls error out GetBoolean vi This VI reads a boolean on the link The re
5. See Chapter 2 37 3 Getting Started 2 The Mathematica kernel is already launched You are notified of this situation by a specific MathLink error message You must quit your Mathematica kernel before running Kernel Evaluation vi again You can either quit it manually or run Close All Links vi found in MLUtil 11b and accessible from the LabVIEW Tools menu 3 The data type is incorrect There are a number of situations that can result in an unexpected data type For instance if you evaluate 10 a symbol Null is returned instead of the integer that you may have expected Similarly if you attempt to evaluate Table Sqrt i i 10 expecting a list of real numbers you may be surprised to get an error message saying that the returned data type does not match the expected type You must specify that you want the numerical value of this list using the Mathematica N command to return a list of real numbers 4 The Mathematica kernel has quit If you send an abort message to the kernel while no evaluation is running it makes the kernel quit 5 You want to use a remote kernel Kernel Evaluation vi cannot launch a remote kernel You can open a link to a remote kernel and use Kernel Evaluation vi on this link For details on opening links consult Getting Connected on page 75 Generic Plot vi and Generic ListPlot vi Generic Plot viand Generic ListPlot vi area pair of VIs designed to fulfill the most common needs of Mathema
6. e AddControls The function used to add new controls to a declared instrument s current list of controls e AddIndicators This function is the same as AddControls except that it applies to indicators Test these functions in conjunction with the CallByReference function To make the exercise more fun use a different example VI Remember to set the path appropriately for your own file system 59 3 Getting Started In 25 echo DeclareInstrument HD LabVIEW examples analysis dspxmpl llb Echo Detector Out 25 Instrument HD Lab VIEW examples analysis dspxmpl llb Echo Detector Echo Detector In 26 OpenVIRef link echo Echo Detector loaded In 27 RunVI link echo Echo Detector running In 28 echo AddControls echo Samples U16 1 Out 28 J Instrument HD LabVIEW examples analysis dspxmpl llb Echo Detector Echo Detector Samples U16 1 In 29 echo AddControls echo Frequency DBL 45 0 In 30 echo AddIndicators echo Echogram DBLList In 31 echo Out 31 Instrument HD Lab VIEW examples analysis dspxmpl llb Echo Detector Echo Detector Samples U16 1 Frequency DBL 45 Echogram DBLList In 32 data CallByReference link echo 1 60 Mathematica Link for LabVIEW Echo Detector successfully operated In 33 ListPlot data PlotJoined gt True Frame gt True PlotLabel gt Experimental echo
7. error out error in no error MLGetString vi MLGetString vi reads a Mathematica character string from Link in and displays it in the String indicator The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Warning This VI does not require the user to call MLDisownString after it has been used since this step is achieved in the CIN String The string read on the link 155 5 Reference Guide MLGetLongDoubleArray vi Link in Link out Long double array error in no error amr d l MLGetLongDoubleArray vi MLGetLongDoubleArray vi calls MLGetDoubleArray vi to get an array of real numbers from Link in The data are returned in the Long double list The parameters used to describe the data structure are returned in the Dimensions Heads and Depth indicators The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Warnings You do not need to call any Disown function after using this VI since this step is achieved in the CIN Long double array The array of real numbers read on the link This cluster contains both the raw data and the parameters used to describe the data structure ExT Long double list The list of real numbers read on the link Dimensions The number of elements i
8. It is used as a subVI of Kernel Evaluation vi Generic ListPlot vi and Generic Plot vi Timeout 60 s The time required by the kernel to evaluate the initialization package Mathematica path Edit the VI and type here the path to the Mathematica kernel on your system Reset the default value of the control to be this path This will automate the launch of the kernel Link out The number of the newly opened link Controls GraphicsWindow ctl GraphicsWindow ctl A custom control to display Mathematica graphics It is a square intensity graph 181 5 Reference Guide MLUtiL IIb if WLU Yle i TYPE A EEA 71 4S Ea ar Init VIs Abort vi Link in e out error in no error n T error out Abort vi Abort vi should be used to abort the computation running on the Mathematica kernel connected to Link in 182 Mathematica Link for LabVIEW Close All Links vi f Close All Links vi Close All Links vi closes links 1 to 100 It should be used to reinitialize Mathematica Link for LabVIEW Codes And Messages vi User defined codes User defined descriptions Codes And Messages vi Codes And Messages vi returns valid error codes merging together the values of the MathLink for LabVIEW errors the MathLink error codes and messages and the global error offset Messages are sorted in increasing order by error codes 132 User defined codes The sorted series of error codes abc User defin
9. Link in Link out l Integer error in no error error out MLGetInteger vi MLGetInteger vi reads an integer number from Link in and assigns it to the Integer indicator The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Warnings 1 This function is not an actual call to MLGetlnteger The number is read from the link through an MLGetLongInteger call and coerced in this VI into an 16 2 MLGetShortInteger is not provided with this distribution MLGetLongInteger should be used instead Integer The integer read from the link MLGetIntegerList vi Link in Link out l Integer list error in no error error out MLGetIntegerList vi MLGetIntegerList vi reads a list of integers from Link in and assigns it to the Integer list indicator The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Warning The user does not have to call MLDisownIntegerList after using this VI since this step is achieved in the CIN 116 Integer list The list of integers read on the link 153 5 Reference Guide MLGetIntegerArray vi Link in Link out Integer array error in no error error out MLGetintegerArray vi MLGetIntegerArray vi gets an array of integers from Link in The data are returned
10. On the other hand if LabVIEW is not installed on the PC where the Mathematica components will run manual installation is necessary as described next Manual installation of the Mathematica components involves manually copying the user 1lib MathLink LabVIEWw directory into the target Mathematica directory If you need to exchange files across platforms for example between a Windows system and a Macintosh or UNIX system the easiest method is often via a TCP IP network TCP IP is required to use MathLink in multi platform configurations for example Mathematica running on a UNIX or Macintosh machine and LabVIEW running on a Windows system After the network connection is established you can then transfer files using FTP File Transfer Protocol an email attachment or any native file transfer options your network topology permits Mathematica packages and notebooks are platform independent ASCII text files that must be transferred in ASCII mode Mathematica application packages must be placed in specific subdirectories of the Applications directory located inside the Add ons directory of the main Mathematica directory In order to configure your system correctly place the entire LabVIEW directory and all of its contents into the Mathematica AddOns Applications directory Next launch Mathematica and select Rebuild Help Index in the Help menu This will add a new item named LabVIEW in the AddOns section of the Mathematica help bro
11. See GMP Good PrimeQ vi 34 graphics 38 92 93 Graphics Viewer vi 92 179 Graphics Window ctl 39 93 181 graphing topographic and magnetic data 118 Hewlett Packard 2 Illustrate ListPlot vi 41 indicator 3 Indicator2bin vi 180 Input 91 Input cluster 71 InputClusterTemplate ctl 134 INPUTPKT 91 INPUTSTRPKT 91 Install vi 17 22 Installation Electronic Distribution 20 from CD ROM 19 Instrument 51 53 201 203 Instrument Declaration and Editing 51 201 Instrument object 51 201 203 Instrument Editing Function 203 intensity graph 39 93 propety node 93 interactive analysis 10 interface instrument 10 LabVIEW 3 6 Mathematica 3 9 notebook 7 10 IP address 80 111 IP address format 111 kernel See Mathematica Kernel Evaluation vi 14 74 173 Kernel Initialization vi 180 Khepera 9 15 24 120 121 209 K Team 209 K Team S A 120 LabVIEW See programming language control 3 data types 57 64 66 diagram 3 front panel 3 Help menu 25 Mathematica Link for LabVIEW indicator 3 interface 3 multitasking 5 27 timing 5 Tools menu 25 Launch See LinkMode Launch Kernel vi 23 181 Link host 50 68 111 Monitor activity 71 83 106 187 name 79 111 Link in 67 Link Monitor vi 83 187 Link out 67 LinkClose 78 80 LinkConnect 76 80 LinkConnectedQ 76 77 LinkHost 50 51 68 80 111 LinkMode 76 Connect 51 76 79 Launch 37 81 88 LinkMode ctl 197
12. When zero is returned it means that an error occurred You then have to call the MLError function to know precisely which error occurred Alternatively you can call MLErrorMessage for a user friendly description that is more useful than numerical error codes Second once you know precisely what happened you can conduct the most appropriate corrective action Finally you need to reactivate the link with MLClearError LabVIEW also has a well defined strategy for managing errors If you are not familiar with this topic you may also want to refer to LabVIEW s documentation A short overview of LabVIEW error management is presented next In LabVIEW error management in sequential I O operations such as file manipulations or any kind of communication relies mainly on error clusters Error In ctland Error Out ct1 located in the Error Cluster area of the Control menu These clusters comprise three elements a boolean named status indicates whether an error occurred an integer is used to report the error code and a string field named source is used to report where the error occurred There are two families of I O VIs depending on their use of error clusters some use error clusters VIs of DAQ libraries VIs of tcp 11b 68 Mathematica Link for LabVIEW and some do not VIs of the GPIB libraries Serial 11b and so on Those that do not use error clusters only return error codes and it is your responsibil
13. command Click the Send Command button to have the command evaluated The result will be displayed in the Session Transcript window The Get Result button is used to fetch a result that may not have come back before the time out has elapsed The slider on the right is used to set the length of the time out interval and the Abort button can be used to abort a running evaluation Finally Quit releases the kernel and stops the execution of the VI 94 Figure 20 The Basic Front End vi front panel Mathematica Link for LabVIEW Command Line ne F Integrate f x xmin xmax gives the definite integral Integrate f x xmin xmax y ymin ymax gives a multiple integral Integrate Sin x Cos x 2 x 1 Power infy Infinite expression encountered 0 Out 3 ComplexInfinity In 4 The block diagram for Basic Front End vi is revealed in Figure 21 We will discuss it briefly here but you may also want to interact with it directly from within LabVIEW First notice the sequence structure at the top of the figure This is where the terminal is initialized and also where the link is opened MLNextPacket is used to establish the connection The first packet emitted by the kernel will be INPUTNAMEPRT Next MLGet String is used to read the string In 1 which is the packet content 95 4 Programming Mathematica Link for LabVIEW Figure 21 The Basic Front End v
14. no error error out MLGetLongIntegerArray vi MLGetLongIntegerArray vi gets an array of long integers from Link in The data are returned in the Long integer list The parameters used to describe the data structure are returned in the Dimensions Heads and Depth indicators The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Warning You do not need to call any disown function after using this VI since this step is achieved in the CIN Long integer array The array of long integers read on the link This cluster contains both the raw data and the parameters used to describe the data structure 116 Long integer list The list of long integers read on the link Dimensions The number of elements in each dimension Heads The Mathematica function name describing the data structure Example the heads of Complex a1 b1 Complex a2 b2 are List eolComplex eol Depth The array depth Example 2 for a 3 x 3 matrix 7 a 158 Mathematica Link for LabVIEW MLGetLongIntegerList vi Link in Link out Long integer list error in no error error out MLGetLongintegerList vi MLGetLongIntegerList vi reads a list of integers from Link in and assigns it to the Long integer list indicator The Value indicator returns a non zero value if the operation was successful or zero if a
15. time Examples are provided in Process Monitoring with MathLink on page 107 e It is not possible to stop the VI server in LabVIEW if it has not been connected To stop it go into Mathematica and connect yourself to the server then shut it down MathLink and Mathematica Link for LabVIEW In order to use Mathematica Link for LabVIEW effectively a basic understanding of its foundations is helpful In this section the global architecture of the package is described A brief introduction to the differences between Mathematica and LabVIEW with respect to data management is also necessary to understand how data are transferred between Mathematica and LabVIEW using Mathematica Link for LabVIEW Software Architecture Mathematica Link for LabVIEW is a straightforward LabVIEW translation of the C functions of the MathLink library Each MathLink VI implements a single MathLink function So for instance you will find in your distribution MLOpen vi MLPutInteger vi and so on However not all of the VIs of your Mathematica Link for LabVIEW distribution are MathLink VIs Several libraries provide utilities or high level VIs which have no direct MathLink counterparts All the VIs implementing MathLink functions make use of a subVI named MathLinkCIN vi MathLinkCIN vi is the only VI in the distribution that contains a LabVIEW Code Interface Node CIN This CIN can be regarded as the heart of the software since this is the interface point
16. Depth The array depth Example 2 for a 3 x 3 matrix 163 5 Reference Guide MLPutIntegerList vi Link in Link out Integer list error in no error error out MLPutintegerList vi MLPutIntegerList vi writes a list of integers to Link in The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Warning In LabVIEW it is not necessary to specify the list length as a separate argument of this function 116 Integer list The list of integers to write to the link MLPutLongDouble vi Link in Link out Long double error in no error error out MLPutLongDouble vi MLPutLongDouble vi calls MLPutDouble vi to write a real number to Link in The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Long double The long double written on the link 164 Mathematica Link for LabVIEW MLPutLongDoubleArray vi Link in Link out Long double array error in no error error out MLPutLongDoubleArray vi MLPutLongDoubleArray vi calls MLPutDoubleArray vi to write an array of long doubles to Link in The data are put in the Long double list The parameters used to describe the data structure are returned in the Dimensions Heads and Depth indicators The Value indicator returns a nonzero v
17. Ident vi 190 MLTYPES ctl 199 Mathematica Link for LabVIEW MLUtil Ilb 24 47 74 86 92 182 multitasking 5 83 name See LinkName New session 46 92 Non standard Installation See See Components to different PCs See to unusual locations 22 numerous solutions to the same problem 116 Open Link vi 75 OpenPanel 54 205 OpenVIRef 205 Organization 23 Output cluster 71 OutputClusterTemplate ctl 135 Package See VIClient packet 90 See MathLink Packet code 90 Packet log 36 90 Packet Parser vi 89 92 191 parallelism 4 5 PathnameSeparator 202 Pictify vi 194 PID Control 15 24 114 115 pipes 77 Plot Benchmark vi 46 portability 2 9 16 Porthum Stephen 118 PostScript 12 92 PPC 9 77 79 82 PreloadInstrument 13 54 205 process monitoring 61 107 Process Simulation and Control control system prototyping 113 215 Index example applicatgion 113 system response See programming language C 65 programming language 2 5 2 5 C 13 64 LabVIEW 3 4 Mathematica 3 4 PutBoolean vi 144 PutBooleanList vi 145 PutBooleanMatrix vi 145 PutDoubleComplex vi 146 PutDoubleComplexList vi 146 PutDoubleComplexMatrix vi 146 PutDoubleMatrix vi 146 PutIntegerMatrix vi 147 PutLongDoubleComplex vi 147 PutLongDoubleComplexList vi 147 PutLongDoubleComplexMatrix vi 147 PutLongDoubleMatrix vi 148 PutLongIntegerMatrix vi 148 PutStringList vi 148 PutStringMatr
18. If you experience difficulties refer to the Troubleshooting notes at the end of this discussion The initial evaluation will take slightly longer than subsequent runs because the Mathematica kernel must be launched on the first run However once the evaluation is completed the result is displayed in the Basic data cluster on the right In this case it appears under Integer since the Expected type was set to Integer as is appropriate for the expected result of 2 2 Next you can try a simple operation that returns a string In the Command box type MathLink for lt gt LabVIEW Select String in the Expected type list and run the VI again The expected 32 Mathematica Link for LabVIEW concatenated string appears in the String box in the Basic data cluster You can also perform a computation involving a more complex data type For example enter Range 10 42 with 1D Integers selected The Basic data cluster disappears and the 1D Arrays cluster becomes visible This feature limits the number of objects that are present at any one time on the front panel CUSTOM SETTINGS New session A sequence of requests issued by Kernel Evaluation vi constitutes a Mathematica session Since definitions are retained throughout the session it is sometimes helpful to restart the kernel as a means of removing conflicting definitions or simply as a way to free memory New se
19. Link for LabVIEW package Its front panel is shown in Figure 12 It is a simple VI that has two clusters a control cluster for input called Input cluster and an indicator cluster Output cluster These clusters are identical and have been designed to pass data used by MathLink functions MathLinkCIN vi is saved in MLComm 11b The Copyright Notice vi isa subVI of MathLinkCIN vi Itis thus executed once every time the CIN is called Since the graphic displayed by the Copyright Notice vi subVI changes randomly at run time it can be used to visually monitor the link activity Note however that this display of graphics may use some CPU time and be limiting in some circumstances There are two ways to hide the front panel of Copyright Notice vi It can be closed by the keyboard shortcut Control w command w on the Macintosh or you can simply unselect the option Show front panel when loaded in the VI setup menu 4 Programming Mathematica Link for LabVIEW MathLink communication interface Input cluster Output cluster Figure 12 The MathLinkCIN vi MLFunction MLFunction front panel Link in 0 Link out 0 Value I Value 0 string long integer lo double 0 00 0 00 long double 0 00 integer list gt a integer list zo long integer list z _ long integer list o double list zo double list zo _ long double list zo long double list o _ The MLGetDouble vi diagram can help in under
20. Mathematica Link for LabVIEW with different backgrounds requirements and expectations Indeed the way you initially use this toolkit will likely depend on your background and existing workflow However because the Mathematica Link for LabVIEW is a flexible conduit for information transfer between Mathematica and LabVIEW a diverse range of workflow scenarios are possible For example if you have extensive LabVIEW experience you may choose to call Mathematica s MathKernel as a subprocess of LabVIEW passing algebraic equations symbolic expressions and real time data to Mathematica for in depth processing and manipulation On the other hand if you are more familiar with Mathematica s interactive notebook interface you may prefer to call LabVIEW VIs virtual instruments from Mathematica acquiring data directly into a notebook for interactive computation and analysis using Mathematica s advanced tools Perhaps you are most interested in reporting and visualization Mathematica is the ideal tool for generating publication quality graphics for your LabVIEW reports Or maybe you want to take 1 Introduction What is Mathematica Link for LabVIEW advantage of Mathematica s interactivity while fine tuning the control function for your LabVIEW RT application Any of these application approaches is a perfectly suitable implementation of the tools contained herein However more powerful solutions are possible by utilizing Mathematica Lin
21. Packet log The log of packets received MLPACKET MLPACKET The packet types are defined in the mathlink h file The most common packets are these INPUTPKT input packet RETURNPKT return packet MESSAGEPKT message packet INPUTNAMEPKT input name packet Time The date and time when the packet was received 193 5 Reference Guide Pictify vi Lines 400 MLPost Link in MLPost Link out psfilename pictfilename error out error in no error Columns 400 Pictify vi Pictify vi calls MLPost with suitable arguments to make a bitmap copy of a PostScript file generated by Mathematica graphics functions You should not be concerned with MLPost link management Pictify vi will automatically launch MLPost when necessary MLPost Link in The current MLPost link identifier psfilename The path to the PostScript file to read pictfilename The path to the bitmap file that will be written wae 1 Columns 400 The bitmap picture width expressed in the number of pixels Lines 400 The bitmap picture height expressed in the number of pixels MLPost Link out The current MLPost link number It should be the same as the incoming link but if an error occurred on this link the MLPost link number is reset to zero 194 Mathematica Link for LabVIEW Read Bitmap vi Path Color palette Link in Link out Line Picture Column error out error in no error Read Bitmap vi Read Bitmap vi is a function to re
22. Print The link is presently empty Out 7 3 In 8 If Link ReadyQ link LinkRead link Print The link is presently empty The link is presently empty The output is dependent on the data you sent and may be different from those illustrated here Making sure that the link is ready before reading it is a wise precaution LinkReadyQ link is included in the If statement for this purpose Keep in mind that if nothing is ready to be read the LinkRead command will hang until something arrives It is important to understand this because LinkRead cannot be aborted A hanging unabortable LinkRead command is undesirable because you increase the likelihood of collecting data whose origin you do not know 100 Mathematica Link for LabVIEW Errors are handled at this stage otherwise there is a risk of not detecting a problem when you open the Figure 23 Simple Data Server vi diagram a C A E pDisabled I32 _ _ E p Disabled OSG Disabled APE m Now it is time to inspect the block diagram to see how this VI is implemented Remember to close the link before moving on to the next section Don t forget the link must be closed by both partners In the Mathematica notebook simply use the LinkClose command In 9 LinkClose link In LabVIEW click the Close the link button and the VI stops 101
23. Programming chapters later in this user guide Overview of Mathematica Link for LabVIEW This section provides a brief description of Mathematica Link for LabVIEW s functionality and multi layered architecture General Functionality Mathematica Link for LabVIEW is a bi directional communication link As implied in previous discussions either application Mathematica or LabVIEW can initiate a message or be called as a subprocess of the other To clarify LabVIEW can call the Mathematica kernel as a subprocess and or Mathematica can call a LabVIEW VI as a subprocess Calling Mathematica from LabVIEW Using the Mathematica kernel from within LabVIEW is somewhat similar to using formula nodes in LabVIEW application diagrams However Mathematica Link for LabVIEW offers one important advantage whereas a formula node resides on a VI diagram and the VI must be stopped and restarted to change the formula a 11 1 Introduction What is Mathematica Link for LabVIEW Mathematica string can be specified in a standard string control on a VI front panel or generated programmatically Changes made to the control string at runtime can be passed immediately to Mathematica for evaluation so new formulae and functions can be attempted interactively without stopping the VI Mathematica Link for LabVIEW provides you with a small set of high level VIs that can be thought of as Mathematica nodes For example one of the bundled VIs ev
24. The advantage of using declared instruments is that you can now use a variable to refer to the instrument Note however that to operate the instrument you need information both about the Instrument itself and about the link where the instrument will be addressed None of the basic operations return data data exchange will be addressed a little later in this discussion so to acknowledge the receipt of your instructions the VI server will send you a message saying that the operation was completed or that an error occurred Start by loading a VI from disk into memory In 8 OpenVIRef link inst or alternatively using the vict1l 11b terminology 53 3 Getting Started PreloadInstrument link inst Mathematica will respond with Frequency Response vi loaded While this command is being processed nothing is visible unless you use LabVIEW tools to inspect VIs that are in memory the VI hierarchy tool or the Unopened subVIs item of the Windows menu You can now display the VI front panel In 9 OpenPanel link inst Frequency Response vi panel displayed Now you should see the VI panel and you can make an attempt to run the VI In 10 RunVI link inst or alternatively using the vict1l 11b terminology RunInstrument link inst Frequency Response vi running Next you can close the panel In 11 ClosePanel link inst Frequency Response v1 panel closed The last operation that you can do with the
25. are Symbol String Integer Real Rational and Complex Note that Number is not one atomic type but rather the union of the 63 3 Getting Started last four types Refer to sections A 1 4 and A 1 5 of The Mathematica Book by S Wolfram 6 for more details Similarly LabVIEW has its own set of elementary data types This set is much larger 26 elementary types than the Mathematica set of atomic types Consult the LabVIEW documentation for an exhaustive list of LabVIEW elementary data types Regarding complex data types LabVIEW handles them either as Arrays Clusters or any combination of both cluster of arrays array of clusters and so on Arrays are multidimensional but must contain elements of identical type whereas clusters are a means of combining data of different types into a single structure Data are transferred between Mathematica and LabVIEW by a layer of C code having its own data structures and types Any textbook on the C programming language will give you details about C data types But you do not need to have any experience programming in C to use Mathematica Link for LabVIEW the data you exchange over the link between Mathematica and LabVIEW are transparently handled by MathLink functions Polymorphism When designing your programming project you have to consider the kind of relationships you will define between the elementary programs written with the language you are using and the
26. but you should be aware of the function of MLPost since you will see that this application is launched when graphics are generated You can consult Graphics Rendering on page 92 for a more detailed description of these issues Another consequence of the use of MLPost is that there is a significant delay in the generation of graphics Also note that the first call to MLPost takes additional time because the application must be launched To integrate Mathematica graphics into LabVIEW VI front panels the bitmap images generated by MLPost are converted to a format compatible with a specially customized LabVIEW intensity graph A copy of this customized intensity graph named Graphics Window ct1 canbe found inMLStart 11b Use of Generic ListPlot vi Like Kernel Evaluation vi this VI can also function either as a main application or as a subVI Some advanced settings to optimize its performance are discussed later in this section BASIC OPERATION Torun Generic ListPlot vi you will need to understand some of the controls on the front panel shown in Figure 7 Above the box labeled Options there is a pop up control that can be used to select the type of graphics you want to make with your data Each type corresponds to a particular Mathematica function ListPlot ListContourPlot ListDensityPlot and ListPlot3D Refer to the Mathematica documentation for an introduction to these functions if you are not already familiar with them Ea
27. complex problem can be addressed with the user interface that is most suitable to the given task For instance in cases where interactive problem solving or symbolic manipulation is necessary Mathematica s textual command line interface is ideal However once a solution or component of a larger system has been well defined LabVIEW s RAD rapid application development tools built in GUI elements and graphical programming language provide a robust environment for high efficiency deployment Combining these two diverse user interfaces interactively yields completely new solution opportunities that are inaccessible using either program alone Mathematica Link for LabVIEW The Mathematica Front End If you are a LabVIEW programmer and are new to Mathematica it is important to understand that the Mathematica user interface is completely text based Mathematica programs are text files and are entered by typing function like command lines The Mathematica front end is an application separate from the number crunching kernel that is in charge of user interaction The front end is where the command lines are usually typed but this is not merely a terminal window The purpose of the front end is to provide a user friendly working environment The front end is used to generate documents called notebooks in which you can place much more than the sequence of command lines intended for the kernel Notebooks are divided into cells that ar
28. configured to run properly without any user intervention While you also have the option of installing all Mathematica Link for LabVIEW components manually as discussed later in this chapter the VI based installer offers a complete automated solution for the majority of installations gt Mathematica Link for LabVIEW Installer 2 Installation The default installation assumes Mathematica and LabVIEW are both installed on a single target PC The target PC drive is first scanned for installed copies of LabVIEW and Mathematica After the user confirms the target path locations the toolkit files are installed in the appropriate places within the LabVIEW and Mathematica file systems The default installation is recommended whenever possible to ensure the full functionality of all Mathematica Link for LabVIEW components If Mathematica and LabVIEW will run on different systems and your network topology does not permit you to locate the Mathematica directory from inside LabVIEW using a standard file browser you may need to install the Mathematica components manually Manual installation and other non standard installation requirements are discussed in Non standard Installation Options beginning on page 21 Standard Installation Procedures This section describes the standard installation process in more detail Since Install vi was constructed using LabVIEW itself the installation process is identical for both Ma
29. data that they manipulate Some languages allow you to build programs capable of using several types of data as arguments the data type they return depends on the kind of argument they are supplied Programs that have this feature are said to be polymorphic Nonpolymorphic programs are typed programs LabVIEW Mathematica and C approach the issue of polymorphism in very different ways Mathematica is polymorphic by nature Among the simplest of Mathematica programs is the function f defined by fx x Although it looks trivial the fact that a programming language can allow the definition of such a function is quite remarkable It can use anything as an argument and thus return any kind of data In Mathematica you can use pattern matching to restrict function definitions to particular patterns But be careful patterns are not data types Patterns represent a much subtler notion which is part of the foundation of symbolic computation Even so you can shape patterns so that they fit some types of data For example 64 Mathematica Link for LabVIEW e x_Integer x42 h x_4n_Integer n SetAttributes h HoldAll The definition of g uses a pattern to limit its evaluation to integers and when it executes it returns an integer Thus defined this way g is a typed function Is the same also true for h Certainly not The pattern used to define h ensures that only integers will be returned by this function but th
30. facilitate the control of the kernel by external programs The links to Microsoft Excel and to Microsoft Word are two examples that were developed by Wolfram Research for users who need to use Mathematica functions from within these popular Microsoft software packages Although generic Mathematica front ends can be defined as applications that use MathLink to run the kernel such applications can be very different from one another Even the front ends developed by Wolfram Research vary in the functions they provide In Tutorial 1llb Basic Front End vi provides functionality similar to the terminal window of the Macintosh or Windows versions of the kernel It can handle any Mathematica expression as input it can return results as well as error messages but it cannot display graphics You will see later that the interface of this VI although simple can be more user friendly than the terminal window of the kernel see Basic Front End vi on page 94 If you develop a LabVIEW application to run the Mathematica kernel recognize that you are actually developing a front end Rather than focusing on the data you expect as result of the evaluation of your command line you have to proceed with the careful and safe management of packets in mind Packet Parser vi provided with this distribution has been designed to simplify the development process Packet Parser vi Packet Parser vi shown in Figure 18 is a general utility upon which any Lab
31. front panel is depicted in Figure 22 its diagram appears in Figure 23 OPERATION OF SIMPLE DATA SERVER VI Upon opening Simple Data Server vi you will find the following items on its front panel e A button labeled Send Data The function of this button is easy to guess it sends data on the link e A button labeled Close the link even easier to guess closes the link e A ring control labeled Select a data type to send This parameter is used to select the kind of data you want to transmit Most elementary data types including all numeric data integer real and complex numbers strings and boolean types are available here Next notice the controls located in the center of the panel and to the right Also notice that only the currently selected data type is editable all others are grayed out Set the value to send Linknamel a e J CSA Sg Aon o gaga lIkds Io ees TR a GIE a a ad Select a data type to send sus Send Data Close the link You first have to open the link in Listen mode in Mathematica the link will be opened in Connect mode in LabVIEW Note this default behavior cannot be programmatically modified when running this VI 98 Mathematica Link for LabVIEW The default value of the link name is set to Ikds in the VI Use this same default link name when opening the link in Mathematica In 1 link LinkOpen Ikds LinkProtocol gt FileMap Li
32. in packets The Packet log maintains an up to date accounting of packets received from the kernel You can ensure that the results of the previous request are returned by the kernel prior to sending the next evaluation simply by monitoring the size of the Packet Log For a more detailed description of this cluster see Packet Parser vi on page 89 Numerical Data Types Compatibility In contrast to Mathematica numerical data type definitions have been relaxed in the initialization of Kernel Evaluation vi to make handling numbers easier In Mathematica integers reals rationals and 36 Mathematica Link for LabVIEW complex numbers are distinct because different Mathematical properties hold for each of these types of numbers In LabVIEW the difference is not that dramatic LabVIEW operators can handle the three kinds of numbers without differentiation For instance the number 2 is an integer and nothing else for Mathematica In LabVIEW it could be an integer a real or a complex number In addition determining the correct data type that results from an evaluation can be a tricky or even impossible exercise What would be the expected data type of I42 or 1 2 In Mathematica evaluating the first one returns an integer and evaluating the second one returns a rational But for LabVIEW the first one could be a complex number and the second could still be regarded as a real number Because of situations like this data
33. instrument AddControls instrument name type value can be used to add several new controls to the control list of a declared instrument AddIndicators instrument name type can be used to add a new indicator to the indicator list of a declared instrument AddIndicators instrument name type can be used to add several new indicators to the indicator list of a declared instrument Note that these three functions all work by making a new instrument declaration In particular the validity of the new values you enter is checked If the Instrument object was saved in a variable the modified instrument is not saved in the same variable When a new instrument object is created by the instrument editing functions it is your responsibility to save it in an appropriate place 203 5 Reference Guide VI Server Management Two operations let you manage the VI server from within Mathematica the connection step and the remote shutdown Connection ConnectToServer is the function that is used to make the connection with MathLink VI Server vi The default values of its arguments match the default values of its LabVIEW partner The normal operation mode is to run the VI server first to open a link in Listen mode using the appropriate platform specific protocol FileMap for Windows PPC for MacOS using the link name 5555 Then you can use the minimal empty argument set of ConnectToServer ConnectToServer will re
34. like display symbol and tag are also invisible elements of this cluster and can be unbundled weal any Menu log The log of MENUPKTs Menu code A number to specify a particular menu See the mathlink h file for details Prompt string The menu prompt string See the mathlink h file for details Syntax log The log of SYNTAXPKT integer values The position at which the syntax error was detected Packet log The log of packets received MLPACKET MLPACKET The packet types are defined in the mathlink h file The most common packets are INPUTPKT input packet RETURNPKT return packet MESSAGEPKT message packet INPUTNAMEPKT input name packet Time The date and time when the packet was received 175 5 Reference Guide MathLink VI Server vi z MathLink VI Server vi Use this VI in conjunction with the functions provided in the VIClient m package When the connection is established you can control LabVIEW applications from within your Mathematica notebook This VI is strongly on the victl llb Vis See the Mathematica Link for LabVIEW documentation for more details Link name The current link name Its default value 5555 matched the default value of the link name opened by the ConnectToServer function of the VIClient package Note that this name is a number whereas the link names are ultimately passed as a string in MLOpen because the TCP protocol which is the default protocol of this VI requ
35. no error GetStringList vi GetStringList vi reads a list of strings from the link Since there is no MathLink function for transferring arrays of strings the list is read as a function List elem 1 elem 2 elem n MLGetString is called sequentially in a For loop Warning Due to the structure of this VI its performance is limited If you need to send large arrays of strings you should probably try to send them as a single string and split it in LabVIEW after collection abc string list The list of strings read from the link 143 5 Reference Guide GetStringMatrix vi Link in Link out string matrix error out error in no error GetStringMatrix vi GetStringMatrix vi reads a matrix of strings from the link Since there is no MathLink function for transferring arrays of strings the list is read as compound Mathematica expression List Listlelem 1 elem 2 elem n MLGetString is called sequentially in two nested For loops Warning Due to the structure of this VI its performance is limited If you need to send large arrays of strings you should probably send them as single strings and split them in LabVIEW after collection string matrix The matrix of strings read from the link PutBoolean vi Link in Link out boolean ae error in no error error out PutBoolean vi PutBoolean vi writes a boolean over the link boolean The boolean value sent over the link 144 Ma
36. of Packet Parser vi is to record all incoming packets that it can handle in dedicated logs and to identify the incoming packets that LabVIEW cannot handle in a generic way The packets that remain untouched by this VI are the packets that return Mathematica expressions RETURNPKT and RETURNEXPRPKT Special cases Graphics Graphics are returned as DISPLAYPKT and DISPLAYENDPKT which contain strings These strings are not appended to the session transcript but to a dedicated string indicator named Graphics which is not visible on the front panel After the DISPLAYENDPKT has been read this string is written in a temporary file by MakeGraphTempFile vi see the description of MakeGraphTempFile vi for further details Once the file is written the Graphics indicator is reinitialized Inputs The INPUTPKT and INPUTSTRPKT also receive special treatment Once the prompt string is read Prompt vi is called to collect the user input as a string which in turn is sent to the kernel wrapped in the suitable packet type Discarded packets Since the VI is intended to analyze the packets returned to LabVIEW by the kernel some types of packets are unlikely ever to be seen by this VI They are CALLPKT EVALUATEPKT ENTEREXPRPKT SUSPENDPKT RESUMEPKT BEGINDLGPKT ENDDLGPKT and the user defined packets FIRSTUSERPKT and ENDUSERPKT These packets are discarded by an MLNewPacket call ILLEGALPKT This packet is just passed downstream to the error hand
37. refers to plot functions keep in mind that there is little limitation to the form that plot functions may take Any functions that return graphical output can be typed here This includes low level graphics primitive commands such as 44 Mathematica Link for LabVIEW Show Graphics Dashing 0 5 0 5 Line 1 1 1 1 or higher level command such as ListPlot Table Sin i i 0 10Pi Pi 5 Generic Plot vi is a general purpose graphics generator that contains as a special case the functionality of Generic LES EP LOE Examine the contents of the Command box in Figure 9 Two graphics named p and q are generated first Next Show GraphicsArray p q produces the picture displayed in the figure Note Intermediate commands must end in a semicolon to avoid a premature exit from the evaluation AN IMPORTANT NOTE ABOUT ASPECT RATIO When using Generic Plot vi the last item in the Command box should always be AspectRatio gt 1 This ensures that the Mathematica image will completely fill the LabVIEW intensity graph If this step is neglected residual data may fill the unused portions of the intensity graph compromising the aesthetic quality of the visual presentation ADVANCED SETTINGS The Timeout and Resolution controls are analogous to the ones found inGeneric ListPlot vi Review Advanced Settings on page 41 for a detailed description PERFORMANCE EVALUATION Record the ti
38. the requirements for complying with regulations specific to quality control of laboratory practice Good Laboratory Practice Good Manufacturing Practice are two reasons to find an alternative methodology Moreover given the growing number of digital instruments in laboratories and the growing use of computer integrated data acquisition systems physically pasting data produced by these systems into paper notebooks is becoming an increasingly anachronistic practice Data can be incorporated into documents such as word processing files but no software has been available specifically for the purpose of recording data in a notebook type form Mathematica Link for LabVIEW could be used for this purpose Given that all the features of Mathematica notebooks are completely described by kernel functions it is possible to build Mathematica programs that automatically generate documents In this way Mathematica can provide scientific computing and typesetting functionality in a single environment Mathematica has a greater functionality than TeX Fortran and other traditional scientific tools because it provides hypertext features and an active link to the kernel for evaluating Mathematica functions Since the functions used to describe notebooks are kernel functions the front end application is not needed Thus Mathematica programs could be developed to generate custom reports from within LabVIEW applications without calling the front end As previo
39. time spent building a communication link between LabVIEW and Mathematica will be recovered by the time saved in using the Mathematica programming language rather than LabVIEW for this particular step 2 Run a LabVIEW VI as a subprocess of Mathematica Running the MathKernel as a subprocess of LabVIEW is often the easiest place to begin However operating LabVIEW VIs or entire LabVIEW applications from within the Mathematica notebook can also be extremely valuable in the conduct of your R amp D projects If you 5 1 Introduction What is Mathematica Link for LabVIEW are not yet used to interacting with your instruments from within Mathematica notebooks this use of Mathematica Link for LabVIEW may sound less natural to you Yet when instruments are operated from within a notebook Mathematica becomes a kind of electronic laboratory notebook offering a convenient way to automatically document your experiments simply save your notebook at the end of each session to make a comprehensive record your entire session 3 LabVIEW provides the GUI for your Mathematica applications Like LabVIEW Mathematica provides a robust application development environment However developing convincing powerful GUIs in Mathematica can be a challenging task On the other hand LabVIEW s diverse set of ready made controls and indicators makes GUI programming quick and easy The Link gives you access to the best of both worlds the Mathematical intel
40. to call MLReady vi and wait for the data to be returned by the other side of the link Warning MLFlush vi should not be confused with MLEndPacket vi which is related to the expression structure MLFlush vi is a buffer management function it has nothing to do with expression or data structures MLReady vi Link in Link out Status MLReady vi MLReady vi tests whether there are data ready to be read from Link in It is analogous to the Mathematica function LinkReadyQ It is often called in a loop as a way of polling a MathLink connection It will always return immediately and will not block Status This indicator is zero when no data is available for reading A nonzero value indicates that data are ready to be read 129 5 Reference Guide MLGetNext vi Link in Link out l MLTYPE error in no error error out MLGetNext vi MLGetNext vi returns the type of the next element in the expression currently being read from Link in The next element always means an element that has not yet been examined by any MathLink get call If the preceding element has been examined but not completely read it will be discarded Warnings 1 To check the type of a partially read element without advancing to the following element call MLGetType vi 2 The integer type code is returned on both the long integer field and the value field of the output cluster The value can still be used for error checking since MLTKERROR 0 The
41. type definitions were relaxed so as to allow coercion of Mathematica data types into LabVIEW when possible without loss of information The following table shows the authorized correspondences between Mathematica evaluation types and those you can select on the Kernel Evalution vi front panel Mathematica type Valid Kernel Evaluation vi types Integer Integer Real Complex Rational Real Complex Real Real Complex Complex Complex Whatever the type of your result you can select Complex in Kernel Evalution vi But if your evaluation returns a real number in Mathematica and you select Integer on the Kernel Evalution vi front panel then you will be notified that the result of your evaluation does not match the expected data type This rule can easily be extrapolated to lists and matrices of numbers Troubleshooting 1 LabVIEW cannot find the Mathematica kernel If you are prompted to locate a MathLink application to launch this generally means that your installation is not properly configured One way to solve the problem is to locate the kernel that you want and launch it manually however this is only a temporary solution Another option is to locate and open Launch Kernel vi then set the MathKernel file path explicitly as outlined on page 22 If you are not comfortable with setting this parameter manually reinstalling Mathematica Link for LabVIEW using the VI based installer should alleviate further difficulties
42. uses front panel lists to specify its options Also VIs are not installable in Mathematica Link in and Link out No special MLINK data type has been defined in this distribution Links are simply identified by an 16 integer Most VIs have both a Link in control and a Link out control that can be used to force data dependency and chain MathLink session VIs across the diagram The Link out value is the same as the Link in value Both can be used to create an artificial data dependency to ensure proper sequencing of operations a standard LabVIEW convention used with several built in functions and libraries of the standard LabVIEW distribution File I O VI Server functions TCP UDP PPC etc Function Value Many MathLink functions return an integer that is used to indicate a possible error This integer is returned in a particular indicator named value that all MathLink VIs have on their front panel In the MathLink VI diagrams the integer error code returned by the MathLink function call is checked by ErrorClusterMaker vi In case it matches a value indicating an error ErrorClusterMaker vi will build an error cluster indicating that an error occured see Introduction to Error Management page 68 and Error Management Tools page 84 Disown Functions MathLink has a set of functions to free memory after arrays of data have been read MLDisownIntegerList MLDisownString and so forth Si
43. Command Prompt vi Prompt vi is used to collect the user input in a pop up panel It is used by Packet Parser vi for INPUTPKT and INPUTSTRPKT processing Prompt in Wire the message used to promt the user here Command The command typed by the user 186 Mathematica Link for LabVIEW Link Monitor vi Link in Link out scanning period 0 1 s B Proceed Timeout 2 s error out error in no error Link Monitor vi Link Monitor vi should be used whenever you want to make sure that something is ready to be read on the link before calling the reading function You can view it as a higher level MLReady function This VI structure is a While loop which is exited if one of the following conditions is true MLReady returns 1 2 MLError returns anything other than MLEOK 3 Timeout exceeded Scanning period 0 1 s This is the time the VI will wait between two successive calls of MLReady and MLError The default value is 100 ms Timeout 2 s This control should be used to set the time you are willing to spend in the loop When the timeout is exceeded the VI stops TF Proceed This indicator should be used to direct the execution of the downstream Vis When Proceed returns False it means either that the link is not ready or that an error occurred MakeGraphTempFile vi MakeGraphTempFile vi writes a PostScript file passed as a string to a temporary file This VI is a subVI of Packet Parser vi Strin
44. Connect Link protocol Open FileMap Connected Link name Close the Link Listen and Connect Modes The Link mode parameter is used with Link name to help each member of the link find the other When the Link mode parameter is set to Listen it indicates that Open Link vi is initiating the link connection and thus should wait for the MathLink partner to connect to it In contrast when the Link mode parameter is set to Connect Open Link vi is responsible for locating the other partner that is waiting in Listen mode Launch mode will be explained later see page 81 Be careful here the link mode terminology can be misleading Listen and Connect do not dictate the status or direction of communication on the link The partner opening a link in Connect mode is not relegated to a client role for instance Once both sides have found each other they can freely exchange data on a peer to peer basis independent of how the connection was originally established In order to establish a connection between Mathematica and LabVIEW you must first create a link In the Mathematica notebook type In 1 link LinkOpen link1 LinkMode gt Listen Out 1 LinkObject link1 2 2 You can consider this initial step as a kind of link declaration The link is now available to anybody who wishes to connect to it At this stage however a link connection has yet to be made You will be unabl
45. DBL SGL Reals or integers CXT CDB CSG Complex reals or integers String String Boolean Either True or False XXXLists Nonempty list of elements of type XXX XXXMatrix Nonempty matrix of elements of type XXX Observe that this validity check is not very strict For each type of number the different formats correspond to different precisions and data ranges However the number is not compared to the data range of its type This does not matter very much since the only possible problem is having an invalid coercion exactly the sort of problem that can happen in LabVIEW diagrams Another important point to remember is that lists and matrices cannot be empty DeclareInstrument DeclareInstrument path controls indicators is a function that declares an instrument after checking that a new Instrument object is valid and can be built based on its arguments First the path is verified To be valid the path must contain at least one PathnameSeparator character The default value for this parameter is PathnameSeparator this is the delimiter for the host system where Mathematica is run You may however need to change this value since the path should be valid for the system where LabVIEW is running Three values are supported and V for the Macintosh UNIX and Microsoft operating systems respectively If the path is valid the VI s name the final string of the path following the last PathnameSepara
46. ETS ctl is the type definition of MathLink packets The definition of the packet types can be found in the mathlink h file Some packets are also detailed in the MathLink reference guide MLPACKET The packet types are defined in the mathlink h file The most common packets are these INPUTPKT input packet RETURNPKT return packet MESSAGEPKT message packet INPUTNAMEPKT input name packet OUTPUTNAMEPKT output name packet 198 Mathematica Link for LabVIEW MLTYPES ctl EAA IMT HEAL FUME MLTYPES ctl MLTYPES ctl is the type definition for MathLink data types MathLink data types are defined in the mathlink h file They are also documented in the MathLink reference guide MLTYPE These are the MathLink data types MLTKSTR Mathematica string MLTKSYM Mathematica symbol MLTKINT integer MLTKREAL real number MLTKFUNC composite expression MLTKERROR error getting type Extra Examples if Extra Examples Extra and advanced VI programming examples can be accessed via the Extra Examples palette More information about these examples can be found in Chapter 4 of this manual Programming Mathematica Link for LabVIEW 199 Mathematica Link for LabVIEW The ViClient m Package Instrument Declaration and Editing Instrument Instrument is an object in which the data structure used by functions to operate remote VIs is saved DeclareInstrument AddControls AddIndicators and SetControls return an Instrument o
47. EW components in non standard places IMPORTANT NOTE While it is possible to use Install vi to install the various components of the Mathematica Link for LabVIEW package in any location you choose this practice is not recommended On line documentation Tool menu functionality and direct access to Link elements from within Mathematica and LabVIEW are only available when the components are installed in the intended locations Auto Installation to Non standard Locations Manually locate the preferred destinations using the file browser buttons on the installer s main installation page Then after acknowledging the warning dialogs proceed with the installation Manual Installation The VI based installer has been included to automate the installation process However you also have the option of manually copying the files from the CD into any location on your drive This option is convenient if you only want to install or re install a specific component Manual installation also provides a useful workaround if you experience a problem with the VI based installer If you are familiar with the organization of the LabVIEW and Mathematica file structures the destinations will be somewhat self explanatory If you are new to either LabVIEW or Mathematica refer to Organization of Mathematica Link for LabVIEW on page 23 for additional background information Configuring the MathKernel Path in Launch Kernel vi One of the duties performe
48. EW is hanging while the LabVIEW evaluation waits in the CIN for the connection The following sequence of commands connects Mathematica to the open LabVIEW link In 1 link LinkOpen link2 LinkMode gt Connect Out 1 LinkObject link2 4 2 In 2 LinkConnect link Out 2 LinkObject link2 4 2 78 Mathematica Link for LabVIEW As before do not forget to close the link on both sides In 3 LinkClose link Link Names You may have noticed that the Mathematica commands we used in the previous sections assigned a value to the Link name parameter while LabVIEW did not the Link name control of the MLOpen parameters area remained empty The result of this omission is that you have to manually locate the link to which you wish to connect You can omit this step by providing a consistent link name to both sides of the link If one side of the link can find a partner hosting a link with a complementary link mode value Connect or Listen and an identical link name the connection step will occur automatically The possible values for link names depend on the protocol used to open a link More details about link names can be found in Wolfram s The MathLink Reference Guide Connecting Two Macintosh Machines over a Network When you run Mathematica and LabVIEW on separate Macintoshes over a network the sequence of instructions for opening a link is the same as just described However you w
49. Experimental echo 0 100 200 300 400 500 Thus you now have access to experimental data from within Mathematica notebooks Close the link with ServerShutdown In 34 ServerShutdown link Server stopped Consult The VIClient m Package on page 201 for a more detailed description of VICLient m package functions Main Limitations of VIClient m Functions e From within Mathematica you can only operate VI controls belonging to a limited set of data types numbers of all kinds strings booleans and lists and matrices of these basic data types You cannot for instance set the value of a cluster control However you still can run these VIs with the current values of the controls default values or values set manually Moreover the to array and from array functions usually make it easy to convert clusters into list of numerical data e Many LabVIEW applications can be considered as process monitoring applications They continue to run and monitor a process 61 3 Getting Started until the operator stops them by clicking a Stop button for instance There is no function in the VIClient m package to dynamically collect the data recorded by these kinds of applications It is possible to run them but no data will be returned and the application needs to be stopped manually In this kind of situation you should introduce a small MathLink subVI in your application to manage communication with Mathematica at run
50. LDING THE MATHEMATICA HELP INDEX Before you can use the freshly installed Mathematica documentation and Hands on exercises you will also need to rebuild the Mathematica Help Index Launch Mathematica then simply select Rebuild Help Index in the Help menu Installing the Electronic Distribution If you have purchased the electronic distribution of Mathematica Link for LabVIEW the first two installation steps are slightly different Begin by expanding the compressed zip Windows or hqx MacOS archive Open the resulting installer folder and double click on Install vi Proceed with the rest of the installation beginning with step 3 from the CD ROM installation instructions listed previously 20 Mathematica Link for LabVIEW Uninstalling Mathematica Link for LabVIEW No dedicated uninstaller application has been included with this package However Mathematica Link for LabVIEW components can be uninstalled manually by removing following directories and all of the items they contain LabVIEW user lib MathLink LabVIEW project MathLink LabVIEW menus MathLink LabVIEW help ML_Help vi LabVIEW help ML_UserGuide pdf Mathematica AddOns Applications LabVIEW More detailed information about the organization and file structure can be found in the section entitled Organization of Mathematica Link for LabVIEW on page 23 Non standard Installation Options Most configurations can be accommodated using the VI base
51. LUtil 11b Nevertheless MathLink function code errors have a specific value the value set in ErrorOffset gbl Thus a MathLink error is detected by a double condition the status is True and the code is 7000 MathLink Error Manager vi uses two main arguments the link number and an error cluster The Display dialog check box is an optional argument If a MathLink error is detected you must identify it precisely by using MLError vi which returns a specific MathLink error code not just a generic error flag Finally the link is reactivated if possible by MEC IEATEErOr VL The last action of MathLink Error Manager vi is to call General Error Handler vi Lists of user defined error codes and error messages are wired to General Error Handler vi to cover both MathLink errors and Mathematica Link for LabVIEW errors The Display dialog check box is wired to the error handler to control the display of error messages Uncheck this box when you want the program to process errors without informing the user In some cases MathLink Error Manager vi performs a corrective action in response specific errors e MLClose for MLEUNKNOWN error e MLClose for MLEDEAD error e MLNewPacket for MLEGETSEO error Error Cluster Maker vi Once a MathLink function has been sent to the link you must check whether or not it returns a nonzero value and bundle the error cluster accordingly A dedicated VI Error Cluster Maker vi has been des
52. Listen 47 76 79 204 LinkName 79 80 111 Macintosh 82 Windows 81 LinkOpen 76 80 204 LinkProtocol 77 80 FileMap 77 82 204 LinkProtocol ctl 197 pipes 77 PPC 9 77 82 204 TCP 9 49 79 81 204 machine name 80 Macintosh 77 79 82 operating system 2 202 MacOS See Macintosh operating system MakeGraphTempfFile vi 92 187 213 Index Manual installation 22 26 See also Configuring Launch Kernel vi 22 Mathematica See programming language command 14 error 85 evaluation 12 expression 89 94 95 front end 3 graphics 12 14 93 kernel 3 notebook 3 7 14 remote kernel 4 session 4 14 stand alone applications 9 Version 18 Mathematica link for Microsoft Word 3 Mathematica Shape Explorer 24 MathKernel exe locating 23 MathLink 13 applications 14 15 error 84 85 error code 86 libraries 9 13 packet 88 92 MathLink directory See directory MathLink Error Managet vi 15 85 87 188 MathLink for LabVIEW error 84 85 libraries 73 75 structure 71 MathLink mode See LinkMode Launch MathLink Temperature vi 107 MathLink VI Server vi 13 47 62 74 176 47 62 214 MathLink VIs 15 MathLinkCIN vi 62 71 75 71 75 93 126 measurement report 10 memory management 26 menu Help 25 Tools 25 MESA Research Institute 118 micromagnetic and microtopographic observations 117 Microsoft Windows 2 52 77 81 202 Windows NT 2 Word 3 MLClear Error vi 126 MLClearErr
53. Mathematica Link for LabVIEW User s Guide Better IEW Consulting May 2005 Second edition second printing Copyright 2002 2005 BetterVIEW Consulting Published by BetterVIEW Consulting 13531 19 Avenue Surrey British Columbia Canada Mathematica and MathLink are registered trademarks of Wolfram Research Inc LabVIEW is a registered trademark of National Instruments Corporation Microsoft and Windows are registered trademarks of Microsoft Corporation Macintosh is a registered trademark of Apple Computer Inc Unix is a registered trademark of AT amp T PostScript is a registered trademark of Adobe Systems Inc All other product names mentioned are trademarks of their respective suppliers Mathematica 1s not associated with Mathematica Policy Research Inc or MathTech Inc BetterVIEW Consulting makes no representation express or implied with respect to this documentation or the software it describes including without limitations any implied warranties of merchantability of fitness for a particular purpose all of which are expressly disclaimed Users should be aware that included in terms and conditions under which Better VIEW Consulting is willing to license the software is a provision that BetterVIEW Consulting and its distribution licensees distributors and dealers shall in no event be liable for any indirect incidental or consequential damages and that liability for direct damages shall be limited to the amount o
54. NPUTPKT input packet RETURNPKT return packet MESSAGEPKT message packet INPUTNAMEPKT input name packet OUTPUTNAMEPKT output name packet 132 Mathematica Link for LabVIEW MLOpen vi linkprotocol linkmode Connect Link out linkname mma2lv il error out error in no error MLOpen vi MLOpen vi opens a MathLink connection MLOpen vi returns an integer that is used subsequently to identify the link Zero is returned if an error occurred Warning This function does not have any value other than the Link out indicator This is the value that is used to check for possible errors linkmode Connect The connection mode linkprotocol Data transport mechanism linkname mma2lyv Name of communication partner a command line or port Link out The number used to identify the link created by MLOpen vi SHEE MLPutMessage vi Link in Link out Message code error in no error error out MLPutMessage vi MLPutMessage vi sends a request to Mathematica to interrupt the current calculation The nature of the interrupt request is a MathLink implementation which varies from version to version See the mathlink h file for details Message code The MLInterruptMessage constant See the mathlink h file for details 133 5 Reference Guide Controls InputClusterTemplate ctl BE InputClusterTemplate ctl InputClusterTemplate ctl is a type definition used by all the Vis of the MathLink libraries to send
55. Notebooks 9 Quickly build distributed LabVIEW applications 10 Stand Alone Mathematica Applications 2 10 A Powerful Synergistic Workflow 10 Overview of Mathematica Link for LabVIEW 11 General Functionality 11 Structure of the Link 13 High Level Functions 13 Development Tools 14 Development Environment 15 2 Installation 17 Standard Installation Procedures 18 System Requirements 18 Non standard Installation Options 21 LabVIEW and Mathematica Running on Different PCs 21 Installing Mathematica Link for LabVIEW components in non standard places 22 Manual Installation 22 Configuring the MathKernel Path in Launch Kernel vi 22 Organization of Mathematica Link for LabVIEW 23 The MathLink Subdirectory of the User lib Directory 23 Other LabVIEW Directories Affected by Mathematica Link for LabVIEW Installation 25 The LabVIEW Subdirectory of the Mathematica Applications Directory 29 LabVIEW Settings 26 Memory 26 Cooperation Level Macintosh Only 2 3 Getting Started 29 Immediate Gratification 29 The MLStart llb Library 30 Kernel Evaluation vi 31 Generic Plot vi and Generic ListPlot vi 38 MathLink VI Server vi 47 MathLink and Mathematica Link for LabVIEW 62 Software Architecture 62 Three Sets of Data Types 63 Peculiarities of Mathematica Link for LabVIEW 66 Introduction to Error Management 68 4 Programming Mathematica Link for LabVIEW 71 The Link Structure Revisited 71 The Use of MathLinkCIN vi 71 Library Contents 73 Getting Connecte
56. ON OF SIMPLE DATA CLIENT VI In this tutorial you will read data from a link into LabVIEW The VI front panel shown in Figure 24 has three areas The area in the upper left region is used to provide information related to the link itself such as its name its ID number and the scanning frequency A second area directly to the right of the first is used to display information related to the data currently read from the link At the top is a specific Mathematica Link for LabVIEW control named MLType It reveals the data type of the last data read on the link as it is defined in the mathlink h file Below this indicator are five indicators that are grayed out in the figure When in use the indicator that corresponds to the current data type becomes active and displays the current data The 102 Mathematica Link for LabVIEW third area at the bottom of the panel is used to display a transcript of the MathLink session Figure 24 Simple Data Client vi front panel Once again we will initiate the link connection in Mathematica to prevent LabVIEW from hanging Use the following expressions in Mathematica to open the link and establish the connection In 1 link LinkOpen Ikdc LinkProtocol gt FileMap LinkMode gt Listen Out 1 LinkObject Ikdc 2 2 In 2 LinkConnect link Out 2 LinkObject Ikdc 2 2 103 4 Programming Mathematica Link for LabVIEW Then go to LabVIEW and run Simple Data Client vi
57. OR Ident vi Error code T EAA MLERRORS error in no error i error out MLERROR Ident vi MLERROR ldent vi identifies the incoming MathLink error code The integer error code is converted to its corresponding value in the MLERRORS ctl custom control Error code This field is the integer MathLink error code returned by MLError vi MLERRORS MathLink error types as they are defined in the mathlink h d E 188 Mathematica Link for LabVIEW MLPACKET Ident vi Packet Code I PET MLPACKET error in no error n error out MLPACKET Ident vi MLPACKET Ident vi converts a packet integer code into a MathLink packet type This VI is used as a subVI of MLNextPacket and other packet handling functions Its function is to make the conversion between the integer returned by the function and the type of the packet as it is described in the mathlink h file Packet Code The integer packet code as returned by MLNextPacket MLPACKET The packet type as defined in the mathlink h file MLPost Init vi Link in MLPost Link out Init error in no error h error out MLPost Init vi MLPostlnit vi is a VI that launches MLPost when necessary that is when the Link in is zero To launch MLPost MLOpen is called in Launch mode and the packets returned by MLPost are discarded up to the return packet used to indicate a possible error Warning MLPost path is computed on your installation relative to the path to MLPost Init vi Do not ch
58. Q vi Both VIs test an integer to determine whether it is a prime number but as per their names one implementation is better than the other one Let us examine Bad PrimeQ vi first 10000000D 0O 0O 0O O ol Test Progress Progr Data set size ei UE Elapsed Time 34 Mathematica Link for LabVIEW Open the diagram of Bad PrimeQ vi Before running the VI make sure that your kernel is not still connected to Kernel Evaluation vi In order to close the connection run Close All Links vi this VI can be found in MLUtil 11b or can be accessed via the LabVIEW Tools menu under MathLink gt Utilities gt Close All Links In Bad PrimeQ vi each number is tested separately with the comparatively trivial Mathematica command PrimeQ number The command is sent for evaluation to the kernel repeatedly for as many times as the length of the list This somewhat inefficient design results in longer than necessary processing times a feature particularly noticeable on slower legacy PC equipment For example in testing a Windows PC with a Pentium processor running at 166 MHz took approximately 0 4 seconds for each element of the list The general structure of Bad PrimeQ vi uses an uninitialized shift register to store the current link reference number When the VI is run for the first time 0 is the shift register value A test is implemented with this criterion to check whether or not a new session must be started Now exami
59. Since the link names match you should not need to locate the link manually After you have started the client the second output should appear You are now ready to send data to LabVIEW Once again this step is particularly easy in Mathematica since the instruction for doing this job is the same regardless of the kind of data you wish to send If possible organize your application windows so that you can keep an eye on the VI front panel while you are writing commands in the Mathematica notebook Then execute the following command In 3 LinkWrite link 123456 True Now look at the VI front panel to see what has happened The indicator named Integer is now active and displays the number The MLType indicator is now indicating MLTKINT which is the MathLink integer type Try to send more data such as In 4 LinkWrite link 1 23456 False Since the option to flush the data was set to False the last parameter sent you will notice that nothing has happened on your VI front panel Now try to send something like this In 5 LinkWrite link 2 34567 True With a True value for the flush option notice that your data has now reached the VI client The data are displayed one after the other in the Real indicator If you miss something you can make sure that the data actually arrived by inspecting the session transcript Now try to send some other kinds of data In 6 LinkWrite link Hello Wo
60. VI on each of two different computers on which Mathematica Link for LabVIEW is installed Before proceeding ensure that your LabVIEW and Mathematica Link for LabVIEW licenses allow this The computers should be able to exchange data over a network Choose consistent link parameters before running the application both applications must use the same protocol and identical link names The first application you will run must be in Listen mode the other must be in Connect mode Note also that when using the TCP protocol you must specify the IP address of the host since there is no field corresponding to the LinkHost option To achieve this use a link name of the form number I Paddress For more details on opening a link see Getting Connected on page 75 Once both applications are running the status of the link is indicated by the Connected indicator After a connection has been established each partner starts to generate random numbers The first one to reach a given threshold set in the Threshold control sends a signal to the other To make this competition fair give the same threshold to both partners The winner will send its data to the loser which will stop the execution of the application 111 4 Programming Mathematica Link for LabVIEW Figure 28 The Distributed vi OOOOOOOOD diagram Fai Won Lost 0000 0 000 0O 0O stop if gt threshold or link is ready This very
61. VIEW front end can be built As soon as you send a command to the Mathematica kernel from within a LabVIEW application packets will be returned The job of Packet Parser vi is to sort them out and process them properly when possible There are two classes of packets packets that LabVIEW can process on a systematic basis those that return a single data type and packets that require a custom LabVIEW application to handle them those that return Mathematica expressions Packet Parser vi will process packets of the first type and pass on to downstream VIs those that require custom treatment 89 Figure 18 The Packet Parser vi front panel 4 Programming Mathematica Link for LabVIEW Session Transcript LASTUSERPKT Link in Link out error in no error error out The main structure of Packet Parser vi is a state machine with three frames Frame 1 is the initial frame in which the link is monitored for the number of seconds set in the Tempo control During this time the link is regularly scanned to detect either errors or incoming data If a packet arrives with no error the state machine jumps to frame 2 Otherwise it jumps to frame 0 which is the exit frame In frame 2 first MLNext Packet is called and the result is time stamped and saved in the Packet log and also displayed in the Packet and Packet code boxes The custom processing of each packet type is discussed in the next section Pack
62. a diverse group of individuals Each scientific discipline uses its own hardware signal sources and mathematical methods Therefore it is extremely difficult to present advanced examples that offer an adequate degree of detail while remaining comprehensible to all Still it is presumed that the majority of Mathematica Link for LabVIEW users will be pursuing advanced topics so the following examples have been included in an attempt to reveal the possibilities It is hoped these examples will be easy to understand and accessible to the largest possible audience while still providing an adequate level of technical detail The following advanced application examples capitalize more fully on the combined strengths of Mathematica and LabVIEW We will introduce these examples only briefly in this text for a more in depth examination you are directed to the programming examples and electronic documentation found in your LabVIEW file system in the user lib MathLink Extra Advanced folder Hopefully the ideas and techniques introduced by these examples will serve as a useful primer for your own advanced MathLink explorations Case Study Development of a vith Application Using Mathematica Link for LabVIE Combining micromagnetic and microtopographic observations of a thin magnetic film into a single graphic display In the opening chapter Mathematica Link for LabVIEW was cast as the central player in a hybrid exploratory workflow This example gr
63. abVIEW s capabilities but in order to try several different scenarios substantial wiring and rewiring is necessary In the exploratory phase the flexibility of the text based Mathematica interface can provide several productivity advantages The Link provides interactive communication to Mathematica s extensive library of functions any of which can be called upon interactively and without the need for rewiring After the details of the solution have been determined you can continue to call Mathematica in a Link based hybrid application or build a stand alone LabVIEW based solution 6 Gain access to powerful Mathematica Add on packages There are several functions in the standard Mathematica packages that have no LabVIEW counterparts In addition there are several third party add on packages that may prove useful for advanced instrumentation applications Examples include Time Series Signal and System Electrical Engineering Experimental Data Analyst and Control System Professional to name a few of the titles available The Link provides access to these powerful packages from within the LabVIEW environment 7 Take advantage of Mathematica s powerful graphics Mathematica has powerful and flexible graphical capabilities You may be interested in making direct use of high level Mathematica graphics functions such as Plot Plot3D ListPlot and so forth Use these capabilities to plot an analytical function describing the theoret
64. ad a bitmap file It returns the picture as a list of data suitable for display in an intensity graph The color palette of the file is also returned in the palette indicator to control the color palette of the intensity graph Read Bitmap vi first loads the specified bitmap file It then stretches or compresses the graphic to fit within a hypothetical window of the specified width and height However it preserves the aspect ratio For example if you specify that you want a 400 x 400 bitmap but the bitmap is twice as wide as it is high then the bitmap will be stretched or compressed so that it is 400 pixels wide exactly the width specified but only 200 pixels high to maintain the aspect ratio The window you see on screen is actually a representation of the 400 x4 00 hypothetical window so extra white space appears above or below the picture Read Bitmap vi calls the only function of the MathLinkCIN vi code interface not which is not a MathLink function Link in Link identifier No operations are conducted on the link by this VI You can however use this connector to sequence the execution of this VI by data dependency Line The picture height Column The picture width Path The path to the bitmap file to read Picture The raw data of the picture The format is suitable for wiring into an intensity graph H EHAE Color palette The color palette of the picture These data should be wired to the corresponding attribute
65. aluates Mathematica expressions using properly formatted strings as arguments and injects the returned results into the VI diagram Other VIs are dedicated to graphical output Integration of these VIs into your LabVIEW application is consistent with the LabVIEW interface even for graphics since Mathematica images are returned and displayed as intensity graphs When the kernel and LabVIEW are running on the same computer the usual Mathematica evaluations execute quickly However functions that return graphics take longer than typical Mathematica evaluations because an intermediate PostScript interpretation step is required Calling LabVIEW VIs from a Mathematica Notebook VIs can also be opened and run interactively from the Mathematica front end The custom VIClient m package included in the Link package interfaces with the specialized MathLink VI Server vi to provide a flexible yet easy to use command interface for launching running and disposing of VIs The command syntax for controlling VIs is consistent with LabVIEW terminology past and present LabVIEW veterans may prefer to use victl 11b terminology PreloadInstrument CallInstrument ReleaseInstrument and so forth People new to LabVIEW and users comfortable with the newer VI Server terminology will likely prefer a command structure consistent with VI Server conventions OpenVIRef RunVI or CallByReference 12 Mathematica Link for LabVIEW CloseVIR
66. alue if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Long double array The array of long doubles written to the link This cluster contains both the raw data and the parameters used to describe the data structure EAT Long double list The list of long doubles written to the link 132 Dimensions The number of elements in each dimension rmf Ia Leif e Heads The Mathematica function name describing the data structure Example the heads of Complex a1 b1 Complex a2 b2 are List eolComplex eol Depth The array depth Example 2 for a 3 x 3 matrix 165 5 Reference Guide MLPutLongDoubleList vi Link in Link out Long double list error in no error error out MLPutLongDoubleList vi MLPutLongDoubleList vi calls MLPutDouble vi to write a list of real numbers to Link in The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Warning In LabVIEW it is not necessary to specify the list length as a separate argument of this function ExT Long double list The list of long doubles to write to the link MLPutLongInteger vi Link in Link out Long integer error in no error error out MLPutLongInteger vi MLPutLongInteger vi writes a long integer to Link in The Value indicator returns a nonzero value if the operatio
67. and start it again j Display error messages When this control is set to True error messages will be displayed to the operator You should switch this option to False when you wish a program to manage errors j He Ee Custom timing settings Set this control to True when you want to fine tune the timing of the kernel operations Abort previous evaluation Use this control to abort an evaluation that is still running before proceeding to the next evaluation 173 5 Reference Guide 174 Basic data Elementary data types are bundled in this cluster Boolean Integer Real Complex String 1D Arrays The five types of lists supported by Kernel Evaluation vi are bundled in this cluster TF 1D Booleans 132 1D Integers oeL 1D Reals toe 1D Complex abc 1D Strings 2D Arrays The five types of matrices supported by Kernel Evaluation vi are bundled in this cluster TF 2D Booleans 2D Integers 2D Reals 2D Complex 2D Strings Session Log The log of the main packet types recorded during the current Mathematica session Fao Message log The log of messages Warning Note that the message texts are not displayed in this log since they are returned as TEXTPKTs Here you find only the message name as Fa 132 Fara Mathematica Link for LabVIEW Display string This field is the result of the concatenation of symbol and tag Its only purpose is to provide a Mathematica
68. ange the file organization of MathLink for Labview This would make impossible to launch MLPost automatically Link in MLPost link When this link is zero MLPost is launched Otherwise nothing happens in this VI Link out The MLPost link it can be either the same link as Link in or the number of the newly created link if Link in was zero MLPost path This is the path to MLPost used by MLOpen vi to automatically launch the program i E E 189 5 Reference Guide MLTYPE Ident vi Type code Iz TYF MLTYPE d iets ID error in no error i error out MLTYPE Ildent vi MLTYPE lIdent vi converts an integer type code into a MathLink data type This VI implements the definition of the different types as they appear in the mathlink h file of your Mathematica distribution Type code This field is the integer returned by MLGetType and MLGetNext functions Valid type codes are these 0 MLTKERROR 89 MLTKSYM 83 MLTKSTR 73 MLTKINT 82 MLTKREAL 70 MLTKFUNC MLTYPE The MathLink data types are these MLTKSTR Mathematica string MLTKSYM Mathematica symbol MLTKINT integer MLTKREAL real number MLTKFUNC composite expression MLTKERROR error getting type They are defined in the mathlink h file 190 Mathematica Link for LabVIEW Packet Parser vi Message log Syntax log Link out Session transcript error out Link in Tempo 1 s error in no error a Packet log a Menu log Packet Parser vi The job
69. annot add an indicator at run time or a dimension to a front panel array or an element to a cluster control Thus we can say that despite the polymorphism of its built in functions and some recent additions to simulate polymorphic behavior LabVIEW remains a typed language The C language is not polymorphic at all although the object oriented language C is When defining a function in C you need to carefully specify the type of each argument as well as the type of the value returned by the function To understand how strict the various MathLink functions definitions are consult Section A 11 Listing of C Functions in the MathLink Library in The Mathematica Book 6 65 3 Getting Started Type Casting Another notion type casting also deserves clarification Type casting is a mechanism to coerce a variable of one type into another type Type casting provides a conversion mechanism for the data that is a transformation of the data from one type to another For instance you can cast a real value into an integer type but this process is not reversible since the number has been rounded during the first conversion When a function is polymorphic it does not need to use type casting since the function is defined for different data types However many LabVIEW functions are still not polymorphic so type casting can occur frequently especially for numerical variables LabVIEW notifies you that type casting will occu
70. aphically illustrates the power of this concept In this exercise we will follow a typical Mathematica Link for LabVIEW workflow while developing a complex hybrid application The tutorial material provided for this example is designed to guide you through the steps 117 4 Programming Mathematica Link for LabVIEW taken by Leon Abelmann Steffen Porthum and Thijs Bolhuis from the Information Storage Technology Group of the MESA Research Institute at the University of Twente The Netherlands The tutorial recreates the workflow used by these intrepid researchers as they developed this real world Mathematica Link for LabVIEW application OVERVIEW A thin magnetic film is observed with a scanning probe microscope A LabVIEW application called SPM vi see Figure 31 is used to acquire both topographic and magnetic patterns of a region under inspection The topographic magnetic separation is achieved with the microscope using a two step process that is each line in the raster scan pattern is passed over twice On the first pass topographical information is recorded Magnetic force data is acquired during a second pass for which the tip is raised to a user selected lift height The lift height typically 20 200 nm is added point by point to the stored topographical data thus keeping the tip sample separation constant and preventing the tip from interacting with the surface These two pass measurements are taken for every scan line to pro
71. as also been introduced When its value is True all active links are closed and two new links are opened to MLPost and the Mathematica kernel This strategy is somewhat crude but it is extremely easy to implement when no other links are being used by an application 46 Mathematica Link for LabVIEW Troubleshooting You are prompted to locate MLPost This means that MLPost has not been found It is likely that the file structure of the MathLink subdirectory of the user 1ib directory has been changed You can either fix it as described in The MathLink Subdirectory on page 23 or you can reinstall Mathematica Link for LabVIEW to correct the problem The plot does not match the command Sometimes the graphics displayed by the VI are inconsistent with the sequence of commands that were sent This may occur when an error condition is encountered the graphic is not returned by the kernel but rather is queued on the link as a result of the error Note graphics queued on the Link will typically display during the next execution If you encounter this problem the best solution is to reinitialize the links by running Close All Links vi from MLUtil 11b orthe Tools menu then rerun Generic Plot vi MathLink VI Server vi MathLink VI Server vi is a general purpose utility that controls LabVIEW VIs and applications from within a Mathematica notebook You typically would run this VI on the computer that is connected to your instru
72. atica Link for LabVIEW Graphics Viewer vi MLPost Link in MLPost Link out Resolution Graph Color palette Graphics Viewer vi Graphics Viewer vi is a utility to render Mathematica graphics in LabVIEW This VI is not intended to be used on a stand alone basis but rather as a subVI of higher level Vis that generate Mathematica graphics It uses a two step process First MLPost is run to make a bitmap version of the Mathematica graphics file Then Read Bitmap vi is called to convert the bitmap file into LabVIEW data See your Mathematica Link for LabVIEW user s guide for more details Resolution The side length of the square picture measured in pixels MLPost Link in This control is used to sequence the execution of Graphics Viewer vi by data dependency Note that Graphics Viewer vi does not conduct any operation on the link to the Mathematica Color palette The color palette of graphics returned by Graphics Viewer vi When this VI is used as a subVI it is necessary to wire this data structure to the corresponding attribute node of the graph of the upper level VI to control the color display MLPost Link out This indicator is used to sequence the execution of Graphics Viewer vi by data dependency Graph The graph generated by Mathematica You can wire this data set to an intensity graph or to the customized type definition GraphicsWindow ctl Color display can be controlled by wiring the color palette to the corresponding at
73. ave been installed and configured properly These introductory materials are intended to get you working with the Link components immediately but provide very little background information Additional insight into Link components and operations is provided in the text that follows The MLStart llb Library In this section you will learn to use the four top level VIs of MiSlLel ls LL Kernel Evalution vi Generic ListPlot vi Generic PLotevi 30 Mathematica Link for LabVIEW e MathLink VI Server vi Understanding these VIs will give you a glimpse into the fundamental capabilities of Mathematica Link for LabVIEW Kernel Evalution vi can be used within LabVIEW diagrams to request a computation step from the Mathematica kernel Generic ListPlot vi provides the Mathematica data visualization tools for LabVIEW data sets from within LabVIEW applications Generic Plot vi can be used to plot from within LabVIEW analytical functions specified in Mathematica syntax MathLink VI Server vi is the tool that controls LabVIEW VIs and applications from within Mathematica notebooks Next we will look at each of these VIs individually Kernel Evaluation vi Kernel Evalution vi allows you to send computation requests to Mathematica s kernel as strings You can type Mathematica commands in this VI s Command box just as you would from within a Mathematica notebook However it is also necessary to specify the data type
74. basic functions of the VIClient m package is to release a VI from memory In 12 CloseVIRef link inst or alternatively using the victl 11b terminology ReleaseInstrument link inst 54 Mathematica Link for LabVIEW Frequency Response vi released Now go into LabVIEW to make sure that Frequency Response vi has been removed from the VI hierarchy To gain further understanding of these tools it might be useful to enter some commands that give rise to errors Start by declaring an instrument that is not on the hard drive In 13 fooinst DeclareInstrument foo vi Out 13 Instrument foo vi foo vi In 14 OpenPanel link fooinst Error 1004 Error 1004 occurred at VI not in memory Possible reasons LabVIEW The VI is not in memory This is a very reasonable reply the VI has not been loaded So you can try to load it In 15 OpenVIRef link fooinst Error 7 Error 7 occurred at VI not found at path Possible reasons LabVIEW File not found OR NI 488 Non existent board Here again you can rely on the error message returned to Mathematica SERVER REMOTE SHUTDOWN The last basic function of the package is named ServerShutdown and it is used to close the link and stop the remote VI server Since it is not instrument specific its only argument is a link to the server There is no specific button on the server panel to stop the VI The reason is that only the client should be ab
75. bitmap version of the Mathematica PostScript graphics is a square matrix of color values The Resolution indicator is used to control the size of this matrix It specifies in pixels the size of a side of the bitmap image A low value will result in a crude rendering and a high value uses a considerable amount of memory the picture size grows as the square of the resolution parameter The setting of this parameter is partly determined by the size of the control in which the picture is displayed For example a value of 300 ensures a nice display on the Generic ListPlot vi front panel The same quality is achieved with a value of 200 in the smaller box of ListPlot Benchmark vi see Performance Evaluation on page 42 Timeout This control specifies the maximum time that the VI will wait for the result of a Mathematica evaluation so that you can avoid being trapped in a long or infinite Mathematica evaluation If you do not mind waiting a long time give this parameter a high value A high value will not delay the evaluation the result will be returned as soon as it is available from the Mathematica kernel If the time out is exceeded before graphics are returned the execution of the VI will stop and nothing will be displayed Note that the time out applies only to the Mathematica kernel s evaluation time It does not include the time required by MLPost to interpret the PostScript In order to estimate a reasonable value for the tim
76. bject Valid Instrument objects have the following pattern Instrument path_String viname_String controls_List indicators_List where path is the access path to the VI up to but not including the VI s name viname is the name of the VI to operate control is a list of the form name_String type_ value_ and indicator is a list of the form name_String type_ The lists of controls and indicators are not necessarily the lists of all of the controls and indicators of the VI You should list in the control and indicator lists only the controls that you want to set a value in and the indicators that you want to read The authorized data types are collected in a list returned by SupportedTypes which is a public function that you can access when the package has been loaded The SupportedTypes elements are themselves documented symbols They are analogous to LabVIEW data types ValidValueQ ValidValueQ type value is a low level utility used to check that the type is valid and that value has the type type It is usually not necessary to use this function except when you have difficulty declaring an instrument with the DeclareInstrument function The validity check performed by ValidValueQ is close to LabVIEW data coercion rules The following table summarizes validity conditions 201 5 Reference Guide Instrument Data Type Mathematica Data Type I8 116 132 Integers U8 U16 U32 Nonnegative integers EXT
77. cOS and Windows platforms System Requirements This distribution of Mathematica Link for LabVIEW is designed for LabVIEW 6 0 or higher and Mathematica 4 1 or higher Mathematica and LabVIEW should be installed on the same PC or one of the applications should be installed on a second computer accessible to the first over a TCP IP network Any system or combination of systems that can run LabVIEW and Mathematica effectively should be appropriate for Mathematica Link for LabVIEW If you are unsure about the capabilities of your system please refer to the LabVIEW and Mathematica documentation for detailed system requirements IMPORTANT NOTE Neither Mathematica nor LabVIEW is part of the Mathematica Link for LabVIEW package each must be purchased separately For information about support for previous version of Mathematica and or LabVIEW contact BetterVIEW directly 18 Mathematica Link for LabVIEW Windows 95 98 ME NT 2000 XP The components in this installation are compatible with Windows 95 98 ME NT Version 3 51 or later 2000 and XP Mathematica Link for LabVIEW cannot run under Windows 3 1 MacOS The MacOS version of Mathematica Link for LabVIEW will run on MacOS 7 6 8 x and 9 x Version 8 5 or higher is recommended MacOS X is not supported at this time and the package has not been verified for use in the MacOSX Classic environment A native OSX version is under consideration Contact BetterVIEW direct
78. ca Link for LabVIEW Mathematica notebook However newcomers to LabVIEW may be unfamiliar with vict1 11b terminology and therefore will prefer to access the same functionality using VI Server terminology In order to provide backward compatibility with older versions of Mathematica Link for LabVIEW while at the same time supporting the current nomenclature some of the functions that follow are offered in two different formats e functions consistent with legacy vict1 11b terminology e functions consistent with the current VI Server terminology The function sets are completely interchangeable so use the function set that feels most natural to you Also feel free to mix and match the functions from both sets in any way that seems most appropriate Basic VI Operations VI Server Nomenclature The following functions permit you to perform simple VI operations using familiar VI Server terminology These functions are not designed to pass control values to the instrument nor can you read indicator values from the VI A function that permits parameter passing is discussed later in this section e OpenVIRef link instrument opens a VI Reference and loads a VI into memory e GetVIState link instrument returns the VI execution state broken idle or running and the panel window state closed open or open and active e RunVI link instrument runs a VI that is in memory with its front panel open Similar to VI Server s Ru
79. ca notebook simultaneously and then run the VI You can observe as the link is first opened on the front panel of Open Link vi After a second or two the connection is made and the LinkConnect command that was hanging in Mathematica is finally evaluated The expected output then appears in your Mathematica notebook On a Macintosh if you omit the link name a window appears to prompt you to locate the link to which to connect You should choose link1 on the machine running your Mathematica kernel 77 On a Macintosh click on the Finder or in the application menu to get out of LabVIEW 4 Programming Mathematica Link for LabVIEW Now you can go back to the Mathematica front end to make sure that the connection is established Query the link by using LinkConnectQ In 4 LinkConnectedQ link Out 4 True The last step of our tutorial is to close the link The only problem that you may have with closing links is forgetting to do it In 5 LinkClose link Do not forget to close the link on both sides Go toOpen Link vi and click the red Close the link button Now repeat the procedure but this time type link2 in the Link name box set Link mode to Listen and run the VI Then open the link in Connect mode within the Mathematica notebook Two things will change First LabVIEW tells you that it is listening Second if you wait too long before switching to Mathematica you will note that LabVI
80. ch function uses a data array as its first argument followed by a series of options Data are passed to the VI as a LabVIEW array named Data located below the Options box options are passed as a string The controls Timeout and Resolution will be discussed later in Advanced Settings on page 41 Fill the first column of the Data control with some data as shown in Figure 7 To run the VI first make sure that the Mathematica kernel is not running by quitting it if necessary You can either quit it manually or 39 Figure 7 Generic ListPlorsva front panel 3 Getting Started use Close All Links vi found in MLUtil 11b and accessible from the LabVIEW Tools menu Now click the Run button Soon an elementary plot will be rendered Since this operation needs to launch both the kernel and MLPost it may take longer than expected On slower older PCs this may take as long as 20 or 30 seconds Link in E Link outhi MLPost link in 2 MLPost link out 2 error in no error error out gListetot_ O g s0 00 Ie Options Resolution 800 a Frame gt True J If this step was successful you can add additional plot options to the evaluation Plot options should be typed in the Options box with commas used for separation if several options are used in sequence However option sequences should not be enclosed in braces as they are in the usual Mathematica syntax nor should option seque
81. ckets returned by the kernel However the limitation of this treatment as noted previously is that the results can be displayed but no further computation can be performed on them Basic MathLink Programming Thus far we have been investigating the VIs specific to Mathematica Link for LabVIEW MathLink functions were rarely used alone Rather higher level VIs that perform somewhat generic functions were the focus of the discussions to this point One drawback of the top level VIs of MLStart 11b is that they have many subVIs these ready made solutions may be overkill if you have a very specific MathLink objective in mind The VIs presented in the following section introduce you to basic MathLink functions that can be used to build smaller focused applications When carefully applied the functions presented here may prove to be somewhat more efficient than the top level VIs in the MLStart 11b library For the examples in this tutorial LabVIEW and Mathematica must run on the same computer The link will use the default local protocol The next two VIs are bare bones applications that exchange data between LabVIEW and Mathematica They can be found in the MathLink gt Tutorial submenu of the LabVIEW Tools menu 97 Figure 22 Simple Data Server vi front panel 4 Programming Mathematica Link for LabVIEW Simple Data Server vi Simple Data Server vi is a stripped down application designed to send data to Mathematica Its
82. d A Mathematica command that returns a graphic Graph The graph generated by Mathematica You can wire this data set to an intensity graph or to the customized type definition GraphicsWindow ctl Color display can be controlled by wiring the color palette to the corresponding attribute node JHH E Color palette This cluster is used to specify the color mapping of Graph MLPost link out Same as MLPost link in Use it to sequence MLPost Message The messages returned by the kernel All the messages generated during the Mathematica session are returned here n 72 Mathematica Link for LabVIEW Kernel Evaluation vi Command Link in New session Display error messages Custom timing settings error in no error Expected type Abort previous evaluation Kernel Evaluation vi Session Log Link out Basic data 1D Arrays 2D Arrays error out Kernel Evaluation vi can be used within a LabVIEW application to send computations to the local Mathematica kernel To run the VI you need to type a Mathematica command and specify the data type expected from the evaluation result See the on line descriptions of the various front panel objects and your Mathematica Link for LabVIEW user s guide for details Command Type here the Mathematica command you want to evaluate Expected type Select here the type of the data you expect to be returned as a result of the evaluation New session Use this control to quit the kernel
83. d 75 Connection between Homogeneous Systems 75 Connection between Heterogeneous Systems over a Network 79 Connections in Launch Mode 81 The Open Link vi Diagram 82 Monitoring Link Activity 82 Link Monitor vi 83 Error Management Tools 84 The Art of Packet Management 88 Packet Parser vi 89 Graphics Rendering 92 Other Graphics Examples 93 Commented Programming Examples 94 Basic Front End vi 94 Basic MathLink Programming 97 Practical Application Examples Advanced Topics and Examples Case Study Development of a Complex Application Using Mathematica Link for LabVIEW Mobile Robotic Experiments 5 Reference Guide MLComm lb VIs MLfFast llb VIs MLGets llb VIs MLPuts llb VIs MLStart lb VIs Controls MLUtil llb VIs Globals Controls Extra Examples The VIClient m Package Instrument Declaration and Editing VI Server Management Basic VI Operations Background Advanced VI Operations Bibliography Appendix Index 107 116 117 120 123 125 126 136 137 149 150 159 160 169 170 181 182 182 196 197 199 201 201 204 204 206 207 209 211 1 Introduction Greetings and thank you for purchasing Mathematica Link for LabVIEW As you grow to understand the structure and organization of the Link we are sure you will discover an ever increasing number of workflow advantages that can be realized by combining the complementary strengths of LabVIEW and Mathematica Where to Begin Everyone comes to
84. d by the VI based installer is to set the default value of the MathKernel Path parameter in Launch Kernel vi This enables LabVIEW to automatically negotiate a MathLink connection without user intervention If you install the Link 22 Mathematica Link for LabVIEW components manually or using separate installer sessions the VI based installer cannot take care of this task for you If you have performed a manual or non standard installation you must set the default MathKernel path manually First locate the MathKernel executable in the Mathematica file hierarchy and make a note of the full path On the Windows platform MathKernel exe is typically found in the top level of the Mathematica file system MacOS users can usually find it inside the Mathematica Files Executables PowerMac folder Next launch LabVIEW and open Launch Kernel vi This VI can be found in MLStart 11b located in the LabVIEW user lib MathLink directory Enter the full MathKernel path from the previous step into the MathKernel Path control on the front panel Set this value as the default by right clicking on the modified path control option clicking on the Mac and selecting the Set as Default option Save the VI to finalize the change and close the panel Your Mathematica Link for LabVIEW VIs should now be configured to automatically negotiate a MathLink connection Organization of Mathematica Link for LabVIEW The Mathematica Link for LabVIEW installation proce
85. d installer and whenever possible this is the preferred installation method The VI based installer uses VI Server functions and Mathematica path information to automatically configure Link components Still some users may have specific requirements that are not specifically supported by the installer The most common variations are discussed next LabVIEW and Mathematica Running on Different PCs Some users may prefer to run Mathematica and LabVIEW on different PCs to distribute the processing load or simply because the LabVIEW and Mathematica licenses are assigned to different PCs If LabVIEW is installed on both PCs simply run the installer on each PC and install only the files corresponding to the resident application More often LabVIEW will be installed on only one of the PCs In this case you may be able to run the installer on one PC and manually browse the second PC s drive to locate the target Mathematica directory across the network If you want to install only the LabVIEW components or only the Mathematica components in a particular session simply set the large checkboxes accordingly on the Installation Selection page 21 2 Installation of the installer VI If Mathematica and LabVIEW components are installed in different sessions you will be required to manually configure the Math Kernel path information in Launch Kernel vi This relatively simple procedure is discussed on page 22 Installing Mathematica Link for LabVI
86. data on the link InputClusterTemplate ctl is a control cluster containing every kind of data that can be sent on a link This control is used by MathLinkCIN vi and by all other Vis implementing MathLink functions Note however that it is hidden from the front panel of all Vis except MathLinkCIN vi Warning Integers are transmitted through the long integer field Input cluster In this cluster are collected all possible kinds of data that can be communicated to the CIN Not all are used together For a given MLFunction call only a limited set of data is used The other variables are passed but not used MLFunction The name of the MathLink function called Link in The link identifier Value Not used as input string The field used to send strings long integer The field used to send integers and long integers double The field used to send doubles SEER EE E long double The field used to send long doubles rma Ii amp integer list The field used to send lists of integers 134 Mathematica Link for LabVIEW long integer list The field used to send lists of long integers DEL double list The field used to send lists of doubles EXT long double list The field used to send lists of long doubles OutputClusterTemplate ctl OUTPUT E OutputClusterTemplate ctl pon OutputClusterTemplate ctl is a type definition used by all the Vis of the MathLink librairies to collect data from the link
87. dded to the LabVIEW menu directory The file in this folder adds Mathematica oriented palette sets to the Control and Function palettes You can access the custom sets by selecting the MathLink Palette Set in the Control or Functions palette Options dialog For more information about setting and selecting custom palette sets refer to the LabVIEW documentation The LabVIEW Subdirectory of the Mathematica Applications Directory If you intend to use Mathematica Link for LabVIEW to control LabVIEW applications from within Mathematica it is necessary to configure your Mathematica installation The configuration procedure is explained in this section If the VI based installer is used to perform a standard installation as outlined earlier in this chapter the Mathematica configuration is completed automatically A second complete copy of the user lib MathLink LabVIEW directory is installed in the Applications directory of the Mathematica file system When running Mathematica and LabVIEW on different systems the LabVIEW directory containing the VIClient m file is the only component of the distribution that must be placed on the computer running Mathematica If LabVIEW is also installed on the computer 25 Exchanging the package among computers under different operating systems Manually configuring Mathematica 2 Installation that will run Mathematica simply use the installer VI to automatically install the LabVIEW directory
88. diary process does not need to open a link Thus you have only one call to MLOpen in the parent process Since Launch mode starts a process its arguments must provide an identification of this process The link name is given in a special form to indicate the process name Launch mode has platform specific properties detailed in the following sections Windows The value of Link name should be a path to the application you want to launch Directories in Windows paths are separated by the back slash character If your hard drive is named C and your application is named app exe the following table gives some examples of valid paths Path Points to C app exe app exe located at the top level of C C APPS app exe app exe located inside a directory named APPS which is on C app exe app exe in the current directory app exe app exe in the directory containing the current director Pp pp y 8 y You can place such paths in the Link name box when starting applications See the diagram of Launch Kernel vi for an example of an implementation of this instruction 81 4 Programming Mathematica Link for LabVIEW Macintosh The value of Link name should be a path to the application you want to launch Directories in Macintosh paths are separated by colons If your hard drive is named HD and your application is named app the following table gives some examples of valid paths Pat
89. dress of your local machine can be joined to the link name In this case the first argument of LinkObject is of the form 5555 machine address If you are running LabVIEW on a remote machine with TCP you should specify the address of that machine with the LinkHost option for ConnectToServer see below You can also specify the machine address in the link name using a name of the form 5555 machine address If your machine is not configured to use TCP IP use the local protocol On the MathLink VI Server vi front panel select the local protocol with the Link protocol control The local procotol is FileMap on Windows systems and PPC on Macintosh systems Then click the Run button without changing any other control value Go back to the standard Mathematica front end to establish the connection with the following command link ConnectToServer LinkProtocol gt Automatic Generally an appropriate choice of options needs to be specified to make the connection possible If you experience difficulties in your first attempts try using the local protocol as noted in the previous paragraph For more details about the options needed to open a link consult Getting Connected on page 75 The next command reveals that the options for ConnectToServer introduced above have the same names as those for LinkOpen but they have different values In 4 Options ConnectToServer Out 4 50 Note On a MacOS computer when t
90. duce separate topographic and magnetic force images of the same area Within a LabVIEW application Mathematica is called to generate a custom 3D plot where the magnetic pattern is superimposed over the topographic data HANDS ON TUTORIAL The hands on tutorial included in the Complex subdirectory of the user lib MathLink Extra Advanced folder will guide you through the process of building this application for yourself The tutorial is divided in two main sections First you will operate the SPM vi from within Mathematica using the MathLink VI Server vi Later you will build a sophisticated LabVIEW application that calls the Mathematica kernel to produce the custom graphics that are the final objective of the tutorial Each section is divided into exercises designed to approximate the different steps required to build a real application It is thus highly recommended that you complete the exercises in the prescribed order For more information and to get started on this tutorial begin by opening Advanced Tutorial nb You will find this notebook along with the other components for this exercise in the LabVIEW user lib MathLink Extra Advanced Complex folder 118 Mathematica Link for LabVIEW eem Measured patterns Magnetic Topographic Figure 31 SPM vi front panel I l 200 z00 400 300 Pattern size 24 Exported patterns Magnetic subset Topographic subset z4 24 20 119 The mobile robot Khepera is no
91. e LabVIEW end Then return to Mathematica and close the link there using In 5 LinkClose link MATHLINK TEMPERATURE VI DIAGRAM Each time the main loop of MathLink Temperature vi is executed MLReady is called to check whether a data request has been received from Mathematica Since the ReadChart function queries the graph by sending the string top to the VI MLReady checks whether the string top has been written on the link The decision to use a string to pass the message to LabVIEW is arbitrary since the string is simply read and discarded by MathLink Temperature vi anyway Another alternative would be to pass an integer to query the graph 109 4 Programming Mathematica Link for LabVIEW Note that because we used this simple mechanism we do not need to call MLGetType or identify the string elsewhere This tutorial is intended to be as simple as possible and as a result the VI is not very robust it could easily be misled if anything other than a string is received However even with this simple structure it works fine After the message string top is discarded to clear the link the data buffer can be sent over the link Then the link is flushed and any potential errors processed One common pitfall to avoid in process monitoring applications is attempting to write the data over the link as soon as they are available Since packets cannot be stacked in large numbers in the link this practice invariably re
92. e kind of arguments it can use does not fit a single type of data The pattern only specifies that it must be something with an integer power the something can really be anything Try it with x 2 2 5 a b 2 3 foo or whatever else you can dream up The final command SetAttributes h HoldAll is present so that the argument of h will not be evaluated before the integer n is extracted Polymorphism in LabVIEW can be misleading if you do not pay careful attention to it As you may know many LabVIEW functions are polymorphic To illustrate this point simply refer to the on line description of the Add operator function the inputs can be any type of number a number and an array of numbers and so forth The data type that is returned depends on the data types of the inputs The fact that most built in functions are polymorphic to varying degrees does not mean that they share this feature with LabVIEW programs that is VIs VIs are not polymorphic When you build a VI you have to specify the types of all the controls and indicators you use your inputs and outputs This also applies to complex data structures such as arrays and clusters Even the polymorphic VI feature introduced in LabVIEW 6 requires duplicate versions of a VI to be constructed one for each data type supported Here again it is also worth noting that there is no way in LabVIEW to programmatically control the data structure of the inputs and outputs of a VI You c
93. e organized in a hierarchical structure You can edit comment on and organize your notebooks in whatever way that best supports the requirements of your work A notebook s structure can be loosely designed in any style that stimulates your creativity or it can also be very rigorously organized Thus you can see that the Mathematica front end is similar to a word processor but it is a word processor connected to the kernel by MathLink It should be noted that the Mathematica kernel can also be accessed directly through a terminal window or used with an array of different front ends One example is the Mathematica Link for Microsoft Word which enables Microsoft Word to act as an alternative front end LabVIEW Panels and Diagrams In contrast with Mathematica the LabVIEW interface is purely graphical LabVIEW programs which are referred to as Virtual Instruments VIs have two separate parts the front panel and the diagram The front panel of a VI is usually the only part visible at run time It is composed of controls and indicators like those on the front panel of a real scientific instrument The diagram is the context where the algorithm is actually implemented As the name of this part of the VI suggests the diagram is not simply text like the source files of conventional programming languages Rather the diagram graphically represents the flow of data to and from various terminals that is diagram representatives of t
94. e out parameter you can make tests in the Mathematica front end to gauge the time required for the computation of graphics that are similar to the ones you plan to visualize in LabVIEW 41 3 Getting Started PERFORMANCE EVALUATION Since rendering graphics can be computationally time consuming a tool has been provided in Tutorial 11b to help you analyze how long it will take on your hardware configuration its name is ListPlot Benchmark vi ListPlot Benchmark vi is designed to generate a sequence of graphical outputs the number of which is set by an Iteration control on the front panel Data are generated by sinusoidal functions and arranged in a matrix having Line lines and Column columns You can control the resolution of the display with the Resolution slider and there is also a control to select the type of plot you want to generate All of the graphics that are generated are stored in a buffer and are displayed sequentially once when they are computed and a second time after the last iteration is completed The second display sequence indicates how the display step will perform on your system To get an idea of the time it takes the Mathematica kernel to create the graphics go to the Mathematica front end and execute the following example commands l Table Cos i Sin j i 20 j 20 Timing ListContourPlot 1 Close any link that may still be open with Close All Link vi Create the same graph
95. e the functions of the VIClient m package to operate LabVIEW applications We will explore each phase sequentially next GETTING CONNECTED TO THE SERVER The first step in connecting to the VI server is to load the VIClient m package The following command will load the package In 1 lt lt LabVIEW VIClient The vIClient m package has a function that automates the connection to MathLink VI Server vi It is named ConnectToServer When queried Mathematica returns the following information about ConnectToServer In 2 ConnectToServer ConnectToServer linkname opt is used to establish a connection to the MathLink VI Server vi Linkname is an optional argument When it is not specified the default linkname is set to 5555 and the default protocol used is TCP If the TCP protocol is properly configured on your machine and if Mathematica and LabVIEW are running on the same machine use the following procedure to get connected Open MathLink VI Server vi and click the Run button without changing any control value Then go back to the standard Mathematica front end to establish the connection 49 Running Mathematica and LabVIEW on different systems over a TCP IP network Running Mathematica and LabVIEW under the same platform using the local protocol 3 Getting Started In 3 link ConnectToServer Out 3 LinkObject 5555 2 2 This output depends on your system configuration In particular the ad
96. e to send data on the link until a connection is made We can verify that no connection exists using LinkConnectedQ 76 The local protocol is platform dependent The Macintosh PPC browser Mathematica Link for LabVIEW In 2 LinkConnectedQ link Out 2 False Our next task is to connect the link In 3 LinkConnect link Out 3 LinkObject link1 2 2 Initially this instruction should hang The indicated output will not appear until the following steps are performed This is logical since the link is now waiting for a partner to make a connection The partner on the LabVIEW side will be Open Link vi This VI s default parameter values are set to Connect for Link mode and the appropriate local protocol for Link protocol The local protocol is the default communication protocol used by the Mathematica kernel and the notebook front end It depends on the hardware platform you are using On Windows a proprietary protocol named FileMap is used On Macintosh systems the local protocol is PPC and UNIX applications communicate through pipes You should refer to the user s guide for your Mathematica installation to learn more about the system specific protocols that you can use On the Open Link vi front panel type link1 in the Link name box to match the link name that was declared in Mathematica Organize your application windows so that you can see both the VI front panel and the Mathemati
97. ection parameters interactively it will be assumed that you are running Mathematica and LabVIEW on 107 4 Programming Mathematica Link for LabVIEW the same computer and that the protocol used is the default local protocol Open the link in Mathematica In 1 link LinkOpen 5678 LinkMode gt Listen Out 1 LinkObject 5678 2 2 In 2 LinkConnect link Out 2 LinkObject 5678 2 2 In LabVIEW run MathLink Temperature vi The connection establishes itself automatically The function of the VI is to return the most recent temperature history to Mathematica upon request Now let us define the function used to query LabVIEW for the data Our query will be composed of three parts First it is necessary to send a short message to say that we want the data Second we need to read the link Finally we want to plot the data All three objectives can be met like this In 3 ReadChart link_ LinkWrite link top ListPlot LinkRead link Frame gt True Axes gt False PlotLabel gt TemperatureHistory 108 Mathematica Link for LabVIEW In 4 ReadChart link Temperature History 0 20 40 60 80 100 The result Live LabVIEW data from a continuously running VI returned to a Mathematica notebook on request CLOSING THE LINK GRACEFULLY Before closing the link in Mathematica first stop the data acquisition in LabVIEW by switching off the Acquisition button This will close the link at th
98. ed descriptions The sorted series of error messages in error code order Copyright Notice vi Copyright Notice vi Copyright Notice vi contains a copyright notice It is a subVI of MathLinkCIN vi The picture will change on a random basis each time a MathLink function is called to give an indication of the link activity This windows can be hidden with the standard keyboard shortcut to close a window 183 5 Reference Guide EmptyListQ vi List mil EmptyList EmptyListQ vi EmptyListQ vi returns True if the incoming list is empty COB List The list that should be tested for emptiness EmptyList True when the incoming list length equals zero False otherwise Empty MatrixQ vi EmptyMatrixQ vi Matrix EmptyMatrix EmptyMatrixQ vi returns True if the incoming matrix is empty Matrix The matrix that should be tested for emptiness EmptyMatrix True if both dimensions equal zero False otherwise 184 Mathematica Link for LabVIEW ErrorClusterMaker vi Function value Function name Error 0 T error out ErrorClusterMaker vi ErrorClusterMaker vi is used to transform a function value into an error cluster This VI is a small utility is used by many Vls of this distribution to build error clusters It checks whether the value returned by the function is zero or not If the return value is zero the status flag is turned to True and the name of the function responsible for t
99. ef and so on More information about the VIClient m package the specialized MathLink VI Server vi and Mathematica s VI Server command line syntax is presented later in this section and at various other places throughout this user guide Structure of the Link The low level component that provides the communication link between the Mathematica kernel and the outside world is Wolfram s own MathLink MathLink is a library of C functions that manage program to program communication The MathLink protocol is responsible for all communication with the kernel including communication with the standard Mathematica front end This protocol can also be used to establish a connection between the kernel and an external MathLink compatible program Interested parties are directed the Mathematica documentation for more information about MathLink Mathematica Link for LabVIEW leverages the MathLink code base The MathLink functions are made accessible to LabVIEW through a Code Interface Node Several VIs are included to implement the most commonly used MathLink functions but all of these VIs call a common CIN VI Inside this single CIN VI the MathLink C functions are actually called This CIN VI also includes a function to read files generated by the PostScript interpreter MLPost Refer to Software Architecture on page 62 for a more detailed description High Level Functions The following VIs provide direct access to the most comm
100. ematica symbol read on the link MLGetDouble vi Link in Link out Double error in no error error out MLGetDouble vi MLGetDouble vi reads a real number from Link in and assign it to the Double indicator The Value indicator returns a nonzero value if the operation was successful of zero if an error occurred In this case the error can be identified with MLError Warning MLGetReal and MLGetFloat functions are not provided in this distribution MLGetDouble should be used instead Double The double read on the link 150 Mathematica Link for LabVIEW MLGetDoubleArray vi Link out Double array error out Link in error in no error MLGetDoubleArray vi MLGetDoubleArray vi gets an array of real numbers from Link in The data themselves are returned in the Double list The parameters used to describe the data structure are returned in the Dimensions Heads and Depth indicators The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Warning You do not need to call any Disown function after using this VI since this step is achieved in the CIN Double array The array of real numbers read on the link This cluster contains both the raw data and the parameters used to describe the data structure bL Double list The list of doubles read on the link Dimensions The number
101. ement each step of your algorithm in the most appropriate language In successive revisions of your application the language that a particular step is written with may even change For example you may first use Mathematica in a phase where you want to prove a concept with minimal development cost Later after the algorithm has 15 1 Introduction What is Mathematica Link for LabVIEW been validated it can be valuable to rewrite the procedure in LabVIEW for speed and integration Thus Mathematica Link for LabVIEW provides a new development framework that neither LabVIEW nor Mathematica can claim on its own The portability of each of the components of this association ensures that applications written with Mathematica Link for LabVIEW will also be portable 16 2 Figure 1 Install vi VI based installer splash screen Installation Mathematica Link for LabVIEW uses an innovative VI based installer When the installation CD is inserted Install vi automatically launches LabVIEW on the target system and begins the installation process see Figure 1 The VI based installer is an ideal choice for LabVIEW toolkit installation offering several distinct advantages over conventional software installers Specifically it can quickly and easily locate the target LabVIEW directory on your system and initiate VI Server functions to initialize VI parameters during the installation process In most cases link components are automatically
102. ement of the link MLGets 11b and MLPuts 11b respectively contain MathLink functions for getting and putting data to and from the link MLFast 11b contains a collection of higher level functions used to transfer common data structures Finally MLUtil 11b provides VIs that are not part of MathLink but that are used either as subVIs of the VIs in the previous libraries or to manage general aspects of MathLink sessions in LabVIEW applications The extra subdirectory contains additional application examples and advanced topics Here you will find the Mathematica Shape Explorer vi a MathLink Simulation and PID Control demo additional graphics examples and an advanced application tutorial The extra folder also contains several VIs and supporting documentation for MathLink operation and control of a Khepera robot The items in the extra folder are useful both as quick demonstrations of the capabilities of Mathematica Link for LabVIEW and as an introduction to how various components can be used in the development of larger projects The MLPost directory contains the MLPost application a PostScript interpreter used for rendering Mathematica graphics in LabVIEW see the section Graphics Rendering on page 92 The LabVIEW subdirectory of the MathLink directory contains Mathematica material and additional advanced programming examples During the standard installation a copy of this directory is also placed in the Mathematica f
103. ent is used to describe the indicators that you want to read These topics will be discussed in The CallInstrument Function and Related Functions on page 56 For right now we will only use the smallest set of arguments needed to declare an instrument The VI we will use in this section is Frequency Response vi a standard example in the LabVIEW distribution The instrument declaration step takes the following form In 5 inst DeclareInstrument HD LabVIEW examples apps freqresp llb Frequency Response vi Out 5 Instrument HD Lab VIEW examples apps freqresp Ilb Frequency Response vi Frequency Response vi The preceding example specifies the VI path information for a typical Macintosh configuration When you reproduce this command on your PC 51 Confused by the doubled path delimiters This Mathematica for Windows convention will be discussed further in a moment 3 Getting Started do not forget to modify the path so that it leads to Frequency Response vi in your file system For example here is its adaptation for a typical Windows configuration inst DeclareInstrument C LabVIEW examples apps freqresp llb Frequency Response vi As mentioned previously the result returned by DeclareInstrument is an Instrument object This indicates that your DeclareInstrument arguments are valid A formal verification of the function arguments is conducted by the DeclareInstrument function before return
104. es after execution The CallByReference command will be discussed in more detail later in this section Front Panel Organization The MathLink VI Server vi front panel is divided into three areas as shown in Figure 10 In the upper left area are the controls used to set the connection parameters They include the protocol used the connection mode and the default link name The link status indicators can be found in the upper right area An LED titled Connected indicates whether the link is connected An error cluster is used in a standard way to report errors and a digital indicator displays the current link number In the lower part of the front panel two boxes provide feedback on the current VI s operation The VI location box displays the path or name 48 Mathematica and LabVIEW run ona single PC configured to use TCP IP Mathematica Link for LabVIEW of the VI being operated and the current operation is highlighted in the Current command box Using MathLink VI Server vi The material in this section is an extension to the material introduced in Hands on Tutorial 1 and 2 as noted at the beginning of this chapter If you haven t worked through these exercises you may want to look at them before continuing MathLink VI Server vi operates in a three phase operational sequence First you must connect to it Second you need to declare Instrument objects in Mathematica Finally you have to us
105. et Processing The following table describes the action taken by Packet Parser vi for all possible kinds of MathLink packets 90 Packet type ILLEGALPKT CALLPKT BEVALUATEPKT RETURNPKT INPUTNAMEPKT ENTE RIEAT PRT BNTEREXPRPKT OUTPUTNAME PKT RETURNTEXTPKT RETURNEXPRPKT DISPLAYPKT DISPLAYENDPKT MESSAGEPKT TEXTPKT INPUTPKT INPUT STRERT MENUPKT SYNTAXPKT SUSPENDPKT RESUMEPKT BEGINDLGPKT ENDDLGPKT Action MLNewPacket MLNewPacket MLGetString MLNewPacket MLNewPacket MLGetString MLGetString MLGetString MLGetString MLGetSymbol MLGetString MLGetString See diagram below See diagram below MLGetString MLNewPacket MLNewPacket q4 MLNewPacket MLNewPacket MLGetLongInteger MLGetLongIinteger Mathematica Link for LabVIEW Comment An error occurred This should be processed by MathLink Error Manager vl Not supported This type of packet should not be returned by the kernel to LabVIEW This should be processed outside of Packet Parser vi Appended to the session transcript This type of packet should not be returned by the kernel to LabVIEW This type of packet should not be returned by the kernel to LabVIEW Appended to the session transcript Appended to the session transcript Should be processed outside of Packet Parser vi Appended to Graphics Appended to Graphics Graphics saved in temporary file and cleared Appe
106. f the data read determines which instruction is called to be specific the data type announced by MLGetType determines which frame of the case structure is required to read the data The implementation details for the cases devoted to the common data types such as MLTKINT MLTKREAL MLTKSYM and MLTKSTR are somewhat self evident However the MLTKFUNC case is a bit more sophisticated This case can accept only Complex as a valid function name If the function name is Complex then its two arguments are read by MLGetLongDouble vi and collected in a single complex number by the appropriate conversion function However if another function was sent it is necessary to notify the user that an invalid function was returned Under these circumstances it is also necessary to discard any remaining packet data 106 Mathematica Link for LabVIEW See the MathLink Reference Guide for more details about packets Finally if the data read was of type MLTKERROR the VI handles this error and stops execution Practical Application Examples So far the examples presented have focused on the low level details of initiating a link connection or on ready made communication utilities While these examples are useful for understanding the underlying structure and the semantics of Mathematica Link for LabVIEW they are somewhat removed from the high level real world applications most users are hoping to build In this section we will prese
107. f the purchase price for the software In addition to the foregoing users should recognize that complex software systems and their documentation contain errors or omissions Better VIEW Consulting shall not be responsible under any circumstances for providing information on or corrections to errors discovered at any time in this book or the software it describes whether or not Better VIEW is aware of such errors or omissions BetterVIEW Consulting does not recommend the use of the software described in this book for applications in which errors or omissions could threaten life injury or significant loss Table of Contents 1 Introduction 1 Where to Begin LabVIEW and Mathematica Added Power and Flexibility through a Synergistic Union The Mathematica Front End LabVIEW Panels and Diagrams Mathematica and LabVIEW Diverse Computing Capabilities Mathematica Link for LabVIEW Practical Implementations 1 Run Mathematica as a subprocess of LabVIEW 2 Run a LabVIEW VI as a subprocess of Mathematica 3 LabVIEW provides the GUI for your Mathematica applications 6 4 Call Mathematica to generate publication quality images and reports with LabVIEW acquired data 5 Add sophisticated Mathematica data processing and symbolic manipulation to LabVIEW applications 6 6 Gain access to powerful Mathematica Add on packages 7 7 Take advantage of Mathematica s powerful graphics 7 7 9 pd O1 JAIA BWW WN ON 8 Create Electronic Laboratory
108. function We will use this VI to experiment with the various methods to open a link Opening a link is the very first event of a link s life cycle This is when the link comes into existence Instructions for opening a link are generally mandatory for both sides of the link and they must be consistent There is one exception to this rule which is when the link is opened in Launch mode see Connections in Launch Mode on page 81 The Open Link vi front panel has three areas as illustrated in Figure 14 The controls in the MLOpen parameters area specify the three parameters used to open a link In the Link status area you will find Link ID an indicator revealing the integer used to identify the recently opened link There are also two LEDs that respectively indicate whether the link is open and connected Finally there is a large button with red letters that you can click to close the link Connection between Homogeneous Systems The procedure for opening a link varies depending on whether or not LabVIEW and Mathematica are both running on the same OS platform e g Windows or Macintosh This section first describes how to open a link when both applications are running on the same platform Opening a link across different platforms is discussed a little later 75 4 Programming Mathematica Link for LabVIEW MLOpen parameters Link status Figure 14 The Open Link mode Link ID 0 Link vi front panel
109. g to write The PostScript file to write It is passed as a string Default directory The directory where the file will be placed The default value of this setting is the Temp directory The other possible value is the LabVIEW default directory Temp file name The name of the PostScript temporary file Al E 187 5 Reference Guide MathLink Error Manager vi Link out MLERRORS error out Link in error in no error MathLink Error Manager vi The function of MathLink Error Manager vi is to detect a MathLink error correct it when possible display the corresponding error message and transmit the information to one of the LabVIEW error handlers The operations conducted by this VI can be divided into four steps 1 Get the MathLink error code and put it in the error cluster If no error occurred the code returned is zero 2 When an error is detected the error message describing the error is added into the source field of the error cluster 3 The error is cleared 4 A corrective action is taken when possible F Display dialog T Check this box when you want to display errors in a dialog box with a single OK button If you want a program to control error processing do not select this option i Error code offset A arbitrary value to shift the error code into the area reserved for user defined error codes between 5000 and MLERRORS MathLink error types as they are defined in the mathlink h d E MLERR
110. h Points to HD app app located at the top level of HD HD Applications app app located inside a folder named Applications which is on HD rapp app in the current folder app app in the folder containing the current folder You can place such paths in the Link name box when starting applications Open Launch Kernel vi and examine its diagram for an example of an implementation of this instruction The Open Link vi Diagram In Figure 15 you can see how the three MathLink VIs are chained together by the link identifier You can also see what is wired to the Link name Link mode and Link protocol connectors of MLOpen vi Note This is the Macintosh version of the VI In the Windows diagram FileMap is used instead of PPC Monitoring Link Activity Since MathLink applications involve inter task communication a common operation that occurs in any MathLink program is monitoring link activity When a link is connected but no transaction is pending it is necessary to monitor potential requests from the link On the receiver side a transaction is always triggered by incoming data which can be detected by the MLReady instruction However calling MLReady ina while loop might not be necessary since the possibility of errors also needs to be tested The simultaneous use MLReady and MLError is the core structure that allows link activity to be monitored 82 Figure 15 The Open Link vi diagram
111. he MathLink VI Server vi is run LabVIEW may hang To solve the problem see pages 75 and 27 Mathematica Link for LabVIEW LinkMode gt Connect LinkProtocol gt TCP LinkHost gt Note also that ConnectToServer returns a LinkObject just as LinkOpen does The main difference between the two functions is that ConnectToServer has default option values that allow the remote control of a LabVIEW application by Mathematica Be aware however that the default value of the LinkHost option is an empty string as it is for LinkOpen This is because relevant values depend on your specific network configuration To establish an operational MathLink link you must connect the link with the LinkConnect function after declaring the link with the LinkOpen function ConnectToServer proceeds to this connection step before returning the LinkObject Thus the LinkObject returned by ConnectToServer must not be connected again such as would be the case if LinkOpen returned it INSTRUMENT DECLARATION Once the connection has been established you must describe the instrument or more specifically the VI you intend to operate A function named DeclareInstrument is provided for this purpose It returns an object of the type Instrument This function usually requires three arguments The first is the path including filename to the VI you want to run The second is a list describing the controls of the target VI as well as their values The last argum
112. he front panel controls and indicators and external data sources Data migrates from inputs to outputs along a network of lines or wires in LabVIEW terminology The nodes of the network are represented by operators or control 1 Introduction What is Mathematica Link for LabVIEW structures that are found in any programming language The major difference between LabVIEW and conventional languages such as C or Fortran is that the program step order of execution cannot be anticipated from the diagram layout as it can be from the instruction order of a source file It is the availability of the input data from a computation step that will initiate its execution This data flow model makes LabVIEW algorithms parallel in nature even if the series of computing steps must be computed sequentially by the CPU Furthermore on platforms that support it LabVIEW takes advantage of the multithreading capabilities of the host operating system Windows UNIX to further overcome the limitations of sequential computing Mathematica and LabVIEW Diverse Computing Capabilities While the differences between the Mathematica and LabVIEW user interaction models are profound differences between these programs are not restricted entirely to their user interfaces Several differences can also be uncovered in each program s computing capabilities Each language has its specificity which makes it more or less appropriate for particular families of computi
113. hen you open a link to the kernel in Launch mode Some users may consider Mathematica Link for LabVIEW the ideal tool for extending the set of Mathematical functions available to LabVIEW applications In this context the Mathematica kernel is launched to perform as a subsidiary process of LabVIEW applications Mathematica is run in MathLink mode and thus returns evaluation results wrapped in packets If you plan to develop your own LabVIEW applications that use the Mathematica kernel to work on nontrivial computations you need to understand how to process packets in your application The sequence of commands will be different from the ones you would use in a Mathematica notebook On the other hand when using the Mathematica kernel from a standard Mathematica notebook you don t need to worry about packets which are handled by the front end application The standard front end distributed with the Mathematica kernel is a separate program that launches the kernel and interacts with it through MathLink If you have not used this front end spend some time becoming familiar with it before starting the development of your LabVIEW application The standard notebook front end should not be regarded as the only option for interacting with the kernel it is only one well developed representative from a general family of external programs that can be 88 Mathematica Link for LabVIEW used for this purpose The kernel and MathLink have been designed to
114. his zero value is placed in the corresponding field of the error cluster Function value This is the integer returned the upstream function Errors may be indicated by a zero or nonzero value depending on the function For MathLink functions a zero value indicates that an error has occurred Function name This is the name of the function that returned the Function value TF Error 0 T Set this box to False if the function values indicating an error are nonzero values Error code offset A arbitrary value to shift the error code into the area reserved for user defined error codes between 5000 and 9999 185 5 Reference Guide ErrorClusterMerger vi Error code Function Name error in no error ErrorClusterMerger vi ML error code offset error out ErrorClusterMerger vi is a small utility used to check that the incoming error cluster does not indicate a previous error If an error occurred the error cluster is not modified Otherwise the error code and source are inserted in the outgoing error cluster Error code This is the error code to be added to the global error offset before insertion in the code field of the outgoing error Function name This is the name of the VI to be included in the source field of the outgoing error cluster ML error code offset A arbitrary value to shift the error code into the area reserved for user defined error codes between 5000 and Prompt vi Prompt in
115. i diagram Session Transcript Get Result T Send Command Disabled oommand Line S Ab Ee Send Command a i r Disabled J Dies k Disabled Dis r 1 Disabled Kd o i E kd a GZ i Scroll Position When the program completes the initialization step Packet Parser vi is used to reinitialize the session This step is necessary to purge all packet logs that may have accumulated during initialization or that may possibly remain from previous runs 96 Mathematica Link for LabVIEW Two loops are nested The smaller loop is used to monitor user interaction The program exits this loop when the user clicks one of the four buttons The nested case structures correspond to the four possible actions Send Command Get Result Abort and Quit Of particular interest is the frame corresponding to the Send Command action The command is passed as a string wrapped in ENTERTEXTPRT This ensures that the evaluation result will be returned as RETURNTEXTPRT that is as a string After sending the command over the link Link Monitor vi is used to detect the incoming result until the time out period elapses The returned string is collected by Packet Parser vi The final step is to split the string returned by Packet Parser vi and to extract the part generated by the last evaluation This approach is interesting since it overcomes the difficulty of parsing the different kinds of pa
116. ical response of your devices Or simply use these flexible Mathematica commands to generate a graphical visualization of the data you just collected Mathematica also has a large set of graphical primitives that enable you to build custom graphical functions Thus you can use Mathematica Link for LabVIEW to display any kind of graphical output that you can imagine 8 Create Electronic Laboratory Notebooks The GUI has become the de facto standard in the computing world in recent years However in some circumstances a text based interface can be preferable to a GUI The Mathematica notebook interface becomes an attractive alternative to the GUI for instruments and data acquisition systems when LabVIEW applications and data acquisition hardware 7 1 Introduction What is Mathematica Link for LabVIEW can be controlled using Mathematica Link for LabVIEW One or a series of Mathematica notebooks can function as a digital metaphor for traditional paper based laboratory notebooks Traditionally scientists involved in research would rigorously record data in paper laboratory notebooks In spite of the increased use of digital technology in the laboratory this traditional recording method is still taught to graduate students However anyone who has done experimental research knows the limitations of this approach after a few months it can be difficult to tell what precisely has been done The necessity of increasing research productivity and
117. ics with ListPlot Benchmark vi and compare the time needed to render the graphics with the time that was needed by Mathematica The most time consuming step in the graphics rendering process is the PostScript interpretation and how long it takes depends on the complexity of the graphic Use ListPlot Benchmark vi with increasing numbers of columns and lines at a fixed resolution You will see that the iteration time depends more on the size of the data set being plotted than on the resolution of the display Also note that some kinds of graphics are more complex than others For instance given 20 lines 20 columns and a 200 pixel resolution it will take about twice as long to evaluate ListContourPlot or ListPlot3D as it will to evaluate ListDensityPlot 42 Mathematica Link for LabVIEW USE AS A SUBVI ListPlot Benchmark vi is an example of the use of Generic ListPlot vi asa subVI of an upper level VI Figure 8 shows how Generic ListPlot vi can be used in this context N iO 0o o o 0 OOOOOoOO 0 G rT Oo gt End se E Figure 8 The ListPlot Benchmark vi diagram E N i Interpolate Color He Rn ri High Color Color Array Fj Ignore Array Resolution I F status a Current error P r ee m Link out PNOOOOOOOODWOOD 43 3 Getting Started Nothing is particularly challenging in this implementation except perhaps the link management scheme The simple
118. igned for this purpose It is located in MLUtil 11b It is a general utility not specific to MathLink that can be used with functions returning either a zero or nonzero value when an error occurs As noted previously MathLink functions return zero in response to an error However many non MathLink functions return their error codes directly and for these functions a value of zero usually means that no error occurred A check box on the front panel specifies which values indicate an error Its default value is True which specifies that a return value of zero indicates an error according to MathLink convention The last input is the function name whose value will be sent in the source field of the error out cluster in the event of an error 8 6 Figure 17 The MathLink Error Manager vi front panel Mathematica Link for LabVIEW MathLink Error Manager Link in Error code offset DX Display dialog T 7000 ML error code MLERRORS MLEUSER error in no error error out Error Cluster Maker vi compares the function value with the check box Error 0 boolean value to compute the value of the status element of the error out cluster Whatever the value of Error 0 the offset value is added to the function value and the result is sent to the code element of error out Finally the function name is sent in the source field only when an error is detected Error Cluster Maker vi
119. ile system The contents of the LabVIEW subdirectory is described in more detail in the section The LabVIEW Subdirectory of the Mathematica Applications Directory on page 25 Each subdirectory installed in the user lib folder also includes a dir mnu where icons and structures of floating palettes are saved If you are not familiar with this LabVIEW feature consult the LabVIEW documentation for more specific information In addition short descriptions of every library or VI are provided as txt files that can 24 On line version of the User s Guide Run the top level VIs and examples from the LabVIEW Tools menu Use the MathLink palettes to enhance your productivity Mathematica Link for LabVIEW be read by the readme vi utility found in the examples directory of the standard LabVIEW distribution Other LabVIEW Directories Affected by Mathematica Link for LabVIEW Installation The installation process also affects other directories of the LabVIEW file system A complete online version of this manual the Mathematica Link for LabVIEW User Guide is installed in the help directory This document can be accessed through the MathLink item in the LabVIEW Help menu A MathLink subdirectory is also created in the project directory of the LabVIEW file system This allows you to launch the main VIs from this distribution directly using the MathLink item in LabVIEW s Tools menu A MathLink sub directory is also a
120. ill need turn on the Program Linking option in the Sharing Setup control panel of the Macintosh that is opening the link in Listen mode Connecting Two Windows Machines over a Network When opening a link between two Windows machines over a network you have to use the TCP procotol See the next section Connection between Heterogeneous Systems over a Network The preceding section dealt with the connection of Mathematica and LabVIEW when both run on the same type of machine This section describes the connection procedure when LabVIEW and Mathematica are running on machines of heterogeneous types Windows UNIX and Macintosh 79 4 Programming Mathematica Link for LabVIEW The TCP Protocol Many scenarios require that several processes communicate in a heterogeneous environment For example you may wish run LabVIEW applications on the Windows computer dedicated to the control of your instruments while running the Mathematica front end from your favorite Macintosh desktop environment At the same time you might run your Mathematica kernel on a fast UNIX CPU The TCP protocol must be used for a distributed application that involves several processes running on several computers The TCP protocol is flexible and you can use it in the same way that you use the local protocol described in the previous section When using TCP however the link name must be a positive integer a port number and you must specify the IP address or
121. in the Integer list The parameters used to describe the data structure are returned in the Dimensions Heads and Depth indicators The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Warning You do not need to call any disown function after using this VI since this step is achieved in the CIN Integer array The array of integers read on the link This cluster contains both the raw data and the parameters used to describe the data structure 1i6 Integer list The list of integers read on the link re Lad Dimensions The number of elements in each dimension i T he Heads The Mathematica function name describing the data structure Example the heads of Complex a1 b1 Complex a2 b2 are List eolComplex eol Depth The array depth Example 2 for a 3 x 3 matrix 154 Mathematica Link for LabVIEW MLGetLongDouble vi Link out Long double error out Link in error in no error MLGetLongDouble vi MLGetLongDouble vi calls MLGetDouble vi to read a real number from Link in and assigns it to the Long double indicator The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Long double The real number read on the link MLGetString vi Link in Link out String
122. indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Warning In LabVIEW it is not necessary to specify the list length as a separate argument of this function 132 Long integer list The list of integers to write to the link MLPutString vi Link in Link out String error in no error error out MLPutString vi MLPutString vi writes a string to Link in The Value indicator returns a non zero value if the operation was successful and O if an error occurred In this case the error can be identified with MLError String The string to write to the link 168 Mathematica Link for LabVIEW MLPutSymbol vi Link in Link out Symbol error in no error error out MLPutSymbol vi MLPutSymbol vi writes a Mathematica symbol to Link in The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Symbol The Mathematica symbol to write to the link MLStart llb MLStart is liii iim t Suz ite ORS 169 5 Reference Guide Vis Generic ListPlot vi Plot type MLPost link in MLPost link out Link in Link out Data p l Graph Options a Color palette Resolution Message error in no error Eee error out Timeout Generic ListPlot vi Generic ListPlot vi can be used to plot a data
123. ing the resulting Instrument consult The VIClient m Package on page 201 for details The output in the preceding example may not appear on your system in fact the output that you do get may be different from what you normally receive For instance in the example output the path string has at least one path delimiter character This delimiter may be not the one you expect from the operating system under which Mathematica is running Since the LabVIEW application you are controlling may be remotely implemented the path name separator used by DeclareInstrument may not have the same value as the system variable PathnameSeparator DeclareInstrument has an option named PathnameSeparator that you can use to adjust this effect to your liking As an example the next command declares on a Macintosh or other type of machine a VI located on a UNIX machine with the PathnameSeparator set to a In 6 inst2 DeclareInstrument readme vi PathnameSeparator gt Out 6 Instrument readme vi readme vi In Windows the path separator is the backslash character This is a potential source of confusion since is also a control character used by Mathematica to format strings For instance t is a tab and r is a carriage return The string represents a single because the first is the Mathematica control character that specifies the interpretation of the second one This is fami
124. ires a number as a link name Numbers are also valid names with Link mode The connection mode Link protocol Data transport mechanism 1 H E Scan period 1s This is used to set the link scanning period When the server is idle that is not processing an input command the VI will monitor incoming commands every Scan period seconds Delay to stop When the server is shut down remotely it is better to wait for a while to let the other partner read the acknowledgment message before closing the link Depending on the protocol used and your network configuration you may need to VI location This is the location of the currently operated VI It can be either a VI name when the VI is already in memory or a VI path when it must be loaded first Connected When switched to True this LED indicates that the link is connected Current command The command currently processed Link ID The number of the link currently operated hm NJ N Mathematica Link for LabVIEW bin2Link vi Link in Link out Output from call Errors Type error out error in no error bin2Link vi bin2Link vi is a subVI of MathLink VI Server vi It is used to unflatten the binary strings returned by Call Instrument vi The series of data type index Position in the case Sa2 Output from call This is the output read from Call Instrument vi See the description of Call Instrument vi in the LabVIEW on line help TF Errors The list of p
125. is returned you will observe the VI loading actually you will hear the disk drive You will see it briefly running and then it will be released from memory This behavior is described in the Cal1 Instrument vi on line documentation If you preload the VI or open a VI reference first the VI is less likely to vanish at completion The rules defining when and how VIs are closed and unloaded from memory is beyond the scope of this discussion Refer to VI Server topics in the LabVIEW documentation for more information To open a VI reference or preload the VI before calling it by reference use the following command sequence 58 Mathematica Link for LabVIEW In 22 OpenVIRef link inst or alternatively using the victl 11b terminology PreloadInstrument link inst Mathematica responds with FrequencyResponse vi loaded Continue with In 23 OpenPanel link inst FrequencyResponse vi panel displayed In 24 CallByReference link inst or alternatively using the victl 11b terminology CallInstrument link inst After the VI terminates Mathematica responds with Frequency Response vi successfully operated Out 24 1000 Since you will use the CallByReference and or the CallInstrument functions to operate VIs you need a convenient way to interactively edit instrument values Three functions are provided for this e SetControls The function used to change the value of a list of declared controls
126. is used by most of the VIs of the Mathematica Link for LabVIEW libraries Code And Messages vi Codes And Messages vi is used as asubVI of MathLink Error Manager vi to collect MathLink and Mathematica Link for LabVIEW error codes and messages 87 4 Programming Mathematica Link for LabVIEW The Art of Packet Management What are packets and when should you be concerned about them This depends very much on the way you use Mathematica Link for LabVIEW When you use it to get control of a LabVIEW application from within a Mathematica notebook you will not see evidence of packets Nor will you have to consider packets when you use MathLink to exchange data between two separate LabVIEW applications You will encounter packets only when you use the Mathematica kernel as a subprocess of a LabVIEW application At this point it should be noted that several of the VIs bundled with Mathematica Link for LabVIEW including the top level VIs in MLStart llb take care of packet management for you If your own applications can be built on top of these VIs the following discussion is mostly academic On the other hand if you want to get the most out of Mathematica Link for LabVIEW and take control of the low level details of your MathLink applications a working understanding of packet management is necessary Packets are special Mathematica functions used by the kernel when it is operated in MathLink mode MathLink mode is automatically turned on w
127. ited If you need to send a large array of strings you should send it as a single string and split it in Mathematica after collection abc string list The list of strings sent over the link 148 Mathematica Link for LabVIEW PutString Matrix vi Link in Link out string matrix HA error in no error error out PutStringMatrix vi PutStringMatrix vi sends a matrix of strings over the link Warning Since there is no MathLink function for transferring an array of strings the list is written as a function List Listlelem1 elem2 MLPutString is called sequentially in two nested For loops Due to this structure the performance of this VI is limited If you need to send a large matrix of strings you should send it as a single string and split it in Mathematica after collection string matrix The matrix of strings sent over the link MLGets IIb Bb HLGets is 149 5 Reference Guide VIs MLGetSymbol vi Link in Link out Symbol error in no error error out MLGetSymbol vi MLGetStymbol vi receives a Mathematica symbol from Link in and displays it in the Symbol indicator The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Warning This VI does not require the user to call MLDisownSymbol after it has been used since this step is achieved in the CIN Symbol The Math
128. ity to manage them safely On the other hand VIs that take advantage of error clusters have an extremely clear error management scheme They first check the cluster status If a pre existing error is detected no other operation is undertaken in the VI Error in and Error out clusters are thus used to chain the VIs that implement the sequence of operations At the end of the sequence you can simply wire one of the LabVIEW error handlers to programmatically control error management Doing so ensures that not more than one error can accumulate during a sequence of operations thereby simplifying troubleshooting operations All Mathematica Link for LabVIEW VIs employ error clusters except those that do not return error codes MLClose vi and MLReady vi for instance You should always wire aMathLink Error Manager vi at the end of the MathLink operation chain this is where MLError and related functions are called 69 4 Use keyboard shortcuts to hide the front panel of Copyright Notice vi Programming Mathematica Link for LabVIEW The Link Structure Revisited The structure of the link between Mathematica and LabVIEW was introduced in Chapter 3 In this first section on Link programming the organization of Mathematica Link for LabVIEW components is described in more detail to help MathLink programmers develop their own applications The Use of MathLinkCIN vi MathLinkCIN vi is the central component in the Mathematica
129. ix vi 149 Read Bitmap vi 93 195 Rebuild Help Index 26 ReleaseInstrument 55 205 robot 120 RunInstrument 13 54 205 RunVI 205 scanning probe microscope 118 selecting an implementation strategy 117 sequence 123 server Simple Data Client vi 102 Simple Data Server vi 98 VI server 47 62 216 ServerShutdown 55 204 SetControls 59 201 203 Simple Data Client vi 102 SPM vi 118 stand alone application 9 standard installation 18 24 25 state machine 90 Sun 2 SupportedTypes 57 201 System Requirements 18 target trajectory 120 TCP See LinkProtocol TCP IP 9 26 204 Tempo 90 timing 5 setting 34 troubleshooting Generic ListPlot vi 47 Generic Plot vi 47 Kernel Evaluation vi 37 troubleshooting conflicting error codes 85 Uninstalling 21 University of Twente 118 UNIX 26 52 80 202 User defined errors gbl 197 ValidValueQ 201 value 67 Verbose 206 VI 3 VI Control 14 VI server 47 62 VI based installer 17 19 20 21 25 VIClient m 12 13 25 47 48 49 52 53 54 56 61 62 107 201 Verbose command 206 Mathematica Link for LabVIEW VIClient m package 47 62 201 6 Windows NT See Microsoft victl lb 14 204 word processor 3 217
130. k for LabVIEW as the central axis in a combined Mathematica LabVIEW workflow In this context the greatest benefits from the synergy between these two powerful applications are realized An exploration of a hybrid Mathematica LabVIEW workflow is presented in the Advanced Topics and Examples section beginning on page 116 Before we explore specific solutions and the steps necessary to realize them additional background discussions are in order LabVIEW and Mathematica Added Power and Flexibility through a Synergistic Union LabVIEW and Mathematica have two important features in common First they are both high level programming languages that allow custom applications to be written efficiently Second programs written with these languages can be run on a variety of operating system hardware configurations specifically under Windows or Windows NT operating systems on computers that use Intel microprocessors or their clones under MacOS on the Apple Macintosh or other computers based on Motorola 68K or PowerPC microprocessors and with UNIX on Sun Hewlett Packard and other workstations LabVIEW and Mathematica both allow fast development of custom portable applications but each offers a completely different user interaction paradigm and workflow Interestingly this is precisely why these two applications can be viewed as extremely complementary Because their user interfaces are somewhat antithetical different aspects of a
131. ket codes The integer codes of the packet types declared in the mathlink h file ma mma Lal Lal abc Error messages The messages describing the various MathLink errors The order of these messages corresponds to the error code order in the Error codes list n 96 Mathematica Link for LabVIEW User defined Errors gbl User i User defined errors gbl Mathematica Link for LabVIEW error codes and error messages 132 User defined codes Mathematic Link for LabVIEW error codes abc User defined descriptions Mathematica Link for LabVIEW error messages abc Source Location of Vlis using the corresponding error codes and Controls LinkMode ctl FE LinkMode ctl An enumeration control corresponding to the three possible values of the linkmode parameter of MLOpen linkmode Connect The connection mode LinkProtocol ctl TEP PPE LinkProtocol ctl An enumeration control corresponding the three possible values of the linkprotocol parameter of MLOpen linkprotocol TCP Data transport mechanism 197 5 Reference Guide MLERRORS ctl MLEAAOA 714 MLERRORS ctl MLERRORS ctl is the type definition of MathLink errors The definition of the error types can be found in the mathlink h file Some errors are also detailed in the MathLink reference guide MLERRORS MathLink error types as they are defined in the mathlink h MLPACKETS ctl PACKET MLPACKETS ctl MLPACK
132. l MathLink transactions In the PID processing case of the state machine the Call PID case depicted in the figure an updated process variable PV value is read from an encapsulated data VI or LV2 style global as this structure is popularly called This PV value is then passed to the PID subVI and on to the graph The PID subVI combines this updated PV value with the front panel Setpoint and PID Parameter settings Using these values a Mathematica command string is constructed and sent to Mathematica for evaluation The output from the PID subVI is plotted on the graph and assuming no MathLink error has occurred the Update Sim case of the state machine is called next The Update Sim case uses methods similar to those outlined above to construct a second Mathematica command string This second string is used by Mathematica to calculate a new PV value in preparation for the next Call PID cycle Lk ha ho a 1 Ta Il FI D 1 3 efa ul ene ers Performance Graph Figure 30 The PID Control Demo vi diagram 115 4 Programming Mathematica Link for LabVIEW When the VI is operating as intended the Call PID and the Update Sim cases are called in a regular alternating sequence However if a MathLink error is detected in either case of the state machine the same case is repeated to prevent erroneous data from destabilizing the controller While this automatic error recovery mechanism is adequate for spurious e
133. le and then call MLClearError vi to activate the link again 126 Mathematica Link for LabVIEW MLClose vi Link in MLClose vi MLClose vi closes a MathLink connection A program must close all links that it has opened before terminating When MLClose vi is called any buffered outgoing data are flushed that is sent to the other partner if its end of the link is still open MLConnect vi Link in _e out error in no error error out MLConnect vi MLConnect vi is used to connect each side of a link together After a link is opened by both sides the connection is not yet established There are two ways to make this connection You can write something on the link and read it from the other side This action will connect both partners if they have not been connected yet Or you can use MLConnect without transmitting anything on the link This solution is preferable when the first emitting partner is not predictable MLEndPacket vi Link in E out error in no error error out MLEndPacket vi MLEndPacket vi marks the end of an expression sent to Link in Once all the pieces of a packet have been sent using MLPutFunction vi MathLink requires you to call MLEndPacket vi to ensure synchronization and consistency Warning MLEndPacket vi does not actually send the expression on the link You still need to flush the link before the link is read by the other partner 127 5 Reference Guide MLError vi Link i
134. le to decide when the service is not 59 3 Getting Started needed anymore There is no indication on the MathLink VI Server vi panel that it is currently used by someone when it is connected Stopping the server in LabVIEW is not advisable although it is possible with the Abort button on the VI s toolbar If you use this method make sure to close the link manually either with Close All Links vi or with MLClose vi Here is the correct way to use ServerShutdown to close the link In 16 ServerShutdown link Out 16 Server stopped THE CALLINSTRUMENT FUNCTION AND RELATED FUNCTIONS The aforementioned basic functions do not allow execution parameters to be passed to and from LabVIEW However VI Server and the victl 11b have more general methods that are capable of passing control values to VIs and collecting indicator values The VIClient m package taps into this functionality with 2 interchangeable functions CallInstrument consistent with vict1l 11b terminology and CallByReference consistent with VI Server terminology We will look at these interchangeable functions in context next First before we can call a VI to exchange data we must declare it And if we want to access the controls and read the indicators we also must declare the controls and indicators of interest in the DeclareInstrument command Apart from the path to the VI two other arguments are necessary The first argument is a list of controls each con
135. leComplexList vi Link in Link out COB iH double complex list error in no error T error out GetDoubleComplexList vi GetDoubleComplexList vi reads a list of complex numbers from the link This VI is based on MLGetDoubleArray vi Warning Since there is no MathLink function to verify that the incoming array fits a list of complex numbers data structure it is your responsibility to ensure that the array fits this data structure when using this VI Inconsistent incoming data read by this VI can lead to a MLEGSEQ MathLink error tDg double complex list The list of double complex numbers read from the link GetDoubleComplexMatrix vi Link in Link out HA double complex matrix error in no error T al error out GetDoubleComplexMatrix vi GetDoubleComplexMatrix vi reads a matrix of complex numbers from the link This VI is based on MLGetDoubleArray vi Warning Since there is no MathLink function to verify that the incoming array fits a matrix of complex numbers data structure it is your responsibility to ensure that the array fits this data structure when using this VI Inconsistent incoming data read by this VI can lead to a MLEGSEQ MathLink error double complex matrix The matrix of complex numbers read from the link 139 5 Reference Guide GetDoubleMatrix vi Link in Link out double matrix error out error in no error GetDoubleMatrix vi GetDoubleMatrix vi reads a matrix of double precisi
136. liar to users who run Mathematica under Windows but might be puzzling to people used to running Mathematica on other operating systems To illustrate further here is another declaration example for a VI located on a Windows machine 52 Mathematica Link for LabVIEW In 7 inst3 DeclareInstrument C LABVIEW README VI PathnameSeparator gt Out 7 Instrument C LAB VIEW README VI README VI UU BASIC OPERATION The VIClient m package has a large number of functions that perform basic operations on remote VIs In order to maintain both backward compatibility and consistency with evolving LabVIEW nomenclature each function is defined by two different terminology sets The first terminology set is analogous to the VIs of vict1 11b Long time LabVIEW users with experience using the functions in vict1l 11b should feel comfortable using the corresponding Mathematica terminology The other function set is patterned after the VI Sever Users coming to LabVIEW after the release of version 5 0 will likely be more comfortable with the VI Server compatible function set The functions sets are completely inter changeable so feel free to use the function set which is most comfortable for you Alternatively if you have no experience with either the traditional vict1 11b VIs LabVIEW 4 1 and earlier or VI Server functions LabVIEW 5 0 and above you are encouraged first to have a look at the examples provided with LabVIEW
137. ligence and pattern matching prowess of Mathematica with the rapid GUI integration of LabVIEW 4 Call Mathematica to r publication quality images and reports with LabVIEW acquired data LabVIEW is an ideal development tool for data acquisition application development However if you want to export your results in printed form your options are limited LabVIEW s bitmap export capabilities and html document generation is fine for on screen review but if you want to produce hard copy printouts the results can be disappointing In contrast Mathematica offers a wide variety of document export options from Postscript and PDF formats to WMF Windows Metafile Format and even AutoCAD DXF files Using the Link a single experiment or project can benefit from the powerful integrated DAQ capabilities of LabVIEW while also enjoying the robust file export capabilities of Mathematica gt Add sophisticated Mathematica data processing and symbolic manipulation to LabVIEW applications Admittedly the Mathematical requirements of many programs are well within the capabilities of LabVIEW However complex problems can call for mathematically sophisticated solutions Sometimes it is much easier to approach a problem using symbolic representation particularly early in the project cycle when all aspects of the problem 6 Mathematica Link for LabVIEW are not well understood or completely defined In other cases a solution is well within L
138. ling VIs 191 192 Link in The link on which the incoming packets will be received Tempo 1 s This indicator is used to slow down the parsing of packets After analyzing each packet the VI halts for the number of seconds indicated in Tempo to let the next packets arrive in the incoming buffer New session F If you set the control to True all logs will be reinitialized Code The packet integer code See the mathlink h file for MLPACKET The packet types as they are defined in the mathlink h file Session transcript An indicator where all text packets are concatenated TEXTPKT INPUTNAMEPKT OUTPUTNAMEPKT and Message log The log of messages Note that the messages texts are not displayed in this log since they are returned as TEXTPKT Only the message name as symbol tag is found here symbol tag Fea 132 Fao Mathematica Link for LabVIEW Display string Menu log This field results of the concatenation of Symbol and Tag Its only purpose is to provide a Mathematica like display The Symbol and Tag are also elements of this cluster and can be unbundled separately if necessary The log of MENUPKTs Syntax log Menu code A number to specify a particular menu See the mathlink h file for code definitions Prompt string The menu prompt string See the MathLink documentation for details The log of SYNTAXPKT integer values The position at which the syntax error was
139. long integer is converted into a defined type by MLType Ident vi Type code These are the valid type codes 0 MLTKERROR 89 MLTKSYM 83 MLTKSTR 73 MLTKINT 82 MLTKREAL 70 MLTKFUNC MLTYPE These are the MathLink data types MLTKSTR Mathematica string MLTKSYM Mathematica symbol MLTKINT integer MLTKREAL real number MLTKFUNC composite expression MLTKERROR error getting type 130 Mathematica Link for LabVIEW MLGetType vi Link in Link out MLTYPE error in no error error out MLGetType vi MLGetType vi returns the type of the current element in the MathLink data stream The difference between MLGetType vi and MLGetNext vi is that MLGetNext vi always looks ahead to a fresh data element that is one that has not been examined by any get call MLGetType vi will stay at the data element that was last accessed if it was not read completely Therefore MLGetType vi can be called several times for the same element Warnings 1 To check the type of the next element in the current data stream call MLGetNext vi 2 The integer type code is returned on both the long integer field and the value field of the output cluster The value can still be used for error checking since MLTKERROR 0 The long integer is converted into a defined type by MLType Ident vi Type code These are the valid type codes 0 MLTKERROR 89 MLTKSYM 83 MLTKSTR 73 MLTKINT 82 MLTKREAL 70 MLTKFUNC MLTYPE These are the MathLink data ty
140. ly if you are interested in native MacOSX support Disk Space Requirements The full installation requires approximately 20 MB of disk space If you plan to use Mathematica on a remote computer you may also need to install networking software Installing the CD ROM version 1 Mathematica Link for LabVIEW is available in two formats a CD ROM distribution and an electronic distribution For electronic distribution installation instructions see page 20 To install the CD ROM version begin by inserting the CD into the appropriate place your on your PC 2 The VI based installer Install vi is configured to auto run when the CD is inserted If LabVIEW is running when the CD is inserted the VI will load immediately If LabVIEW is not running it will launch before Install vi loads If the CD auto run capability has been disabled on your PC simply open the CD and double click on the Install vi icon Alternatively you can manually open the VI from inside the LabVIEW editor 3 Once running Install vi walks you through the necessary installation steps Select the items to install using the large yellow checkboxes provided If both LabVIEW and Mathematica will run on the same system be sure to check both items Install Lab VIEW Components and Install Mathematica Components 4 After selecting the components to install you will be asked to verify the installation paths Install vi uses more than one platform specific sea
141. many different ways to build hybrid applications based on Mathematica LabVIEW and MathLink In fact it is usually possible to develop a variety of different solutions for the same application challenge For example one possible solution might use a LabVIEW GUI and send a computation to the Mathematica kernel using Kernel Evaluation vi as demonstrated by GoodPrimeQ vi and the PID Control Demo vi Another implementation could use a Mathematica notebook as an alternative interface to instruments operated through MathLink VI Server vi This implementation would be similar to the Echo Detector example presented in The CallInstrument Function and Related Functions on page 56 A third 116 Mathematica Link for LabVIEW implementation could be derived from the method used to interact with MathLink Temperature vi It might even use customized MathLink transactions to enhance the data transfer rate Depending on your application several other implementations might also be possible however it is important to realize that the implementation strategy you choose will determine the mode of user interaction the performance level the development cost and to some extent the type and accuracy of the data collected In order to make the best use of Mathematica Link for LabVIEW it is necessary to examine more complex examples than those used previously to illustrate the basics of MathLink programming Unfortunately LabVIEW and Mathematica users are
142. me required to evaluate the following commands from the standard Mathematica front end e Plot3D Sin x y x 0 2Pi y 0 2 e ListPlot Range 10 Close all the links that may still be open with Close All Link vi and run Plot Benchmark vi In this way you can evaluate the same commands and compare the evaluation time to appreciate how Generic Plot vi performs on your system 45 Figure 9 The Generic Plot vi front panel 3 Getting Started Link in f Link outhi MLPost link in JB MLPost link out l2 error in no error error out Command p Plot3D Sin x y x 0 2 y 0 2 AspectRatio gt 0 5 Show ContourGraphics p ColorFunction gt Hue AspectRatio gt 0 5 Show GraphicsArray p q AspectRatio gt 1 In 1 Show gcc Graphics of type GraphicsArray cannot be combined with other types of graphics USE AS A SUBVI Plot Benchmark vi is an example of the use of GenericPlot vias asubVI Generic Plot vi can be wired into a diagram in very much the same way as Generic ListPlot vi Thus see the discussion pertaining to Generic ListPlot vi under Use as a SubVI on page 43 Plot Benchmark vi has several features that have not been discussed yet First it has a message box that displays Mathematica messages This is accomplished by a small algorithm that extracts the last message generated by the kernel from within the message string returned by Generic Plot vi A New session button h
143. mented in Mathematica Link for LabVIEW Development Environment A number of examples are provided to illustrate how the MathLink VIs can be used in various combinations in LabVIEW applications Some of the examples are based on the standard VIs contained in the LabVIEW distribution Others such as the PID Control Demo and the Mathematica Shape Explorer are entirely new VIs developed for the package using Link components as subVIs Some of the standard VI library examples are slightly modified to take advantage of MathLink functions more efficiently Comments guidelines and recommendations are also provided in the VIs to accelerate the development of your own MathLink applications Some real applications to control the Khepera mobile robot are also included Although they cannot be run without the robot they illustrate the possibility of developing robust real time applications with Mathematica Link for LabVIEW For basic work you might be satisfied to use the higher level VIs of Mathematica Link for LabVIEW However as you continue to work with Mathematica Link for LabVIEW you will soon realize that it is truly an open development environment that allows you to make creative use of the respective strengths of Mathematica and LabVIEW Also depending on the application you may wish to have an interface that is more oriented toward either Mathematica or LabVIEW Once the interface has been chosen you are still completely free to impl
144. ments The VI works in combination with the VIClient m package to provide VI Server like control of LabVIEW VIs from within a Mathematica notebook MathLink VI Server vi first opens a link in Listen mode and waits for Mathematica to connect The VIClient m package provides the function ConnectToServer on the Mathematica side which automates the connection step This connection when established is not specific to the LabVIEW application the link can be used to run any VI or application saved on a volume accessible to the computer where MathLink VI Server vi is running It can even manage several VIs simultaneously 47 3 Getting Started Figure 10 The MathLink VI Server vi front panel Scan period 1s f 00 lg Connected 2 Delay to stop I 00 E Link ID 0 error out Link name 915555 Link mode Listen E E E Link protocol ai E TCP VI location Macintosh HD LabVIEW examples app Tempsys RunInstrument ales Preloadinstrument Releaselnstrument OpenPanel The VIClient m package s main functions are basic to load a VI into memory to release it after use to manipulate its front panel and to run it The basic function set does not allow arguments to be passed to a VI nor can data be collected after the VI s execution However another function based on the similarly named VI Server function CallByReference allows parameter passing through VI controls as well as the return of VI indicator valu
145. n Link out MLERRORS MLError vi MLError vi returns an integer code identifying the most recent MathLink error that occurred on Link in The description of the different types of errors can be found in the mathlink h file of your MathLink developer kit If no error has occurred on the link then MLError vi returns zero MLEOK Use MLErrorMessage vi to get a detailed description of the error and use MLClearError vi to clear the link when possible Error A nonzero value indicates that no error occurred MLERRORS MathLink error types as they are defined in the mathlink h MLErrorMessage vi Link in Link out Error Message MLErrorMessage vi MLErrorMessage vi returns a text string describing the most recent error that occurred on Link in Warning Error messages displayed by the MathLink Error Manager vi are coded in the MLConstant gbl global variable They should however match one another Error Message The description of the error as it is reported in the mathlink h file 128 Mathematica Link for LabVIEW MLFlush vi Link in o out error in no error error out MLFlush vi MLFlush vi immediately transmits any data buffered for sending over the connection MathLink usually buffers the data before they are written on the link To make sure that all necessary data have been sent and are thus available to the other partner it is necessary to call MLFlush vi Only after doing this does it make sense
146. n VI method e CloseVIRef link instrument unloads a VI that was loaded using OpenVIRef All these functions correspond to VI Server terminology Refer to the LabVIEW documentation for more details Basic VI Operations vict1l 11b Nomenclature The same four functions are now presented in their vict1 11b form Once again you cannot send control values to the instrument nor can you read indicator values from the VI using these functions This will be discussed later in this section 205 5 Reference Guide e PreloadInstrument link instrument loads a VI into memory e GetInstrumentState link instrument returns the VI execution state broken idle or running and the panel window state closed open or open and active e RunInstrument link instrument runs a VI that is in memory with its front panel open e ReleaseInstrument link instrument unloads a VI that was loaded using PreloadInstrument All these functions correspond to VIs of vict1 11b Refer to LabVIEW Version 4 documentation for more details about vict1 11b Basic VI Operations Front Panel Control The following front panel control functions are equivalent using either VI Server or vict1 11b terminology e OpenPanel link instrument displays the front panel of a loaded VI e ClosePanel link instrument closes a VI front panel Advanced VI Operations CallIByReference VI Sever terminology or CallInstrument victl 11b terminology a
147. n each dimension Heads The Mathematica function name describing the data structure Example the heads of Complex a1 b1 Complex a2 b2 are List eolComplex eol Depth The array depth Example 2 for a 3 x 3 matrix 7 g 7 156 Mathematica Link for LabVIEW MLGetLongDoubleList vi Link out Long double list error out MLGetLongDoubleList vi Link in error in no error MLGetLongDoubleList vi callsMLGetDoubleList vi to read a list of real numbers from Link in and assigns it to the Long double list indicator The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Warning The user does not have to call MLDisownLongDoubleList after using this VI since this step is achieved in the CIN ExT Long double list The list of long doubles read on the link MLGetLongInteger vi Link out Long integer error out Link in error in no error MLGetLonglInteger vi MLGetLongInteger vi reads an integer number from Link in and assigns it the Long integer indicator The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Long integer The long integer read from the link 157 5 Reference Guide MLGetLongIntegerArray vi Link in Link out Long integer array error in
148. n error occurred In this case the error can be identified with MLError Warning The user does not have to call MLDisownLongIntegerList after using this VI since this step is achieved in the CIN 132 Long integer list The list of long integers read on the link MLPuts Ilb IB HLPuts Vis 159 5 Reference Guide VIs MLPutInteger vi Link in Link out Integer error in no error error out MLPutinteger vi MLPutlnteger vi writes an integer to Link in The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Warning This VI does not implement the actual MathLink function MLPutlnteger It calls MLPutLongInteger and coerces the 116 to an 132 before sending it over the link Integer The integer to write on the link MLPutDouble vi Link in Link out Double error in no error error out MLPutDouble vi MLPutDouble vi writes a real number to Link in The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Warning MLPutReal and MLPutFloat functions are not provided in this distribution MLPutDouble should be used instead Double The double to write on the link 160 Mathematica Link for LabVIEW MLPutDoubleArray vi Link in Link out Double array error in no error error o
149. n of both LabVIEW and Mathematica can create a more transparent user experience where the tools recede and your attention is focused directly on the problem at hand rather than on overcoming the limitations of the tools To expand on this further consider a typical example The development of a measurement program often involves an initial stage where you write a quick LabVIEW prototype to control and interact with your instrument This first prototype is rarely sufficient to produce high quality data you may need to fine tune your acquisition strategy redefine acquisition parameters modify the sampling environment in some way reposition your sensors and so on several times before you are ready to collect useful data Many trials yielding unusable results may pass before the final data are recorded At this stage of the process you need to forget the instrument as much as possible and focus on the research itself Now image how useful it would be if you could run a test and acquire a sample with a single CallInstrument command This single command would return data directly into your Mathematica notebook where you could then interactively analyze the results in order to compute the parameters for the next experiment Imagine a workflow where you simply call a new data set from your instruments on command then interactively process analyze plot manipulate plot again and so on Here is an example of a typical development lo
150. n was successful or zero if an error occurred In this case the error can be identified with MLError Long integer The long integer to write to the link 166 Mathematica Link for LabVIEW MLPutLongIntegerArray vi Link in Link out Long integer array error in no error error out MLPutLongIintegerArray vi MLPutLongIntegerArray vi writes an array of integers to Link in The data are put in the Long integer list The parameters used to describe the data structure are written in the Dimensions Heads and Depth indicators The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Long integer array The array of integers written to the link This cluster contains both the raw data and the parameters used to describe the data structure 116 Long integer list The list of integers written to the link 137 Dimensions The number of elements in each dimension Heads The Mathematica function name describing the data structure Example the heads of Complex a1 b1 Complex a2 b2 are List eolComplex eol Depth The array depth Example 2 for a 3 x 3 matrix rma Ll 167 5 Reference Guide MLPutLongIntegerList vi Link in Link out Long integer list error in no error error out MLPutLongIntegerList vi MLPutLongIntegerList vi writes a list of integers to Link in The Value
151. nally LabVIEW has its own set of built in error codes One global variable ErrorOffset gbl1 located in MLUtil 11b is used to map MathLink and Mathematica Link for LabVIEW error codes into LabVIEW s user defined error space The default offset value has been set to 7000 Keep in mind however that this value could interfere with other custom LabVIEW applications that might be running simultaneously In case of conflict open ErrorOffset gb1 and set the offset value accordingly to map Mathematica Link for LabVIEW errors into a non conflicting range MathLink Error Manager vi MathLink Error Manager vi shown in Figure 17 is intended to be placed at the end of a MathLink session Its job is to check for and ascertain the identity of any MathLink error that may have occured display the corresponding error message possibly take a corrective action and then clear the error This VI first reads the incoming error cluster to detect a possible MathLink error Two criteria are used for this purpose the status value and the code value It is a good idea to start by testing the status flag of the incoming error cluster When it is set to False no error was detected and we can proceed to the next VI Should the status flag be set to True it does not necessarily mean that the error originated in a 85 4 Programming Mathematica Link for LabVIEW MathLink function It could have come from any other function including one from M
152. name e g praline or praline wolfram com for the machine to which you want to connect Example We can reproduce the connection sequence explained in the preceding section using the TCP protocol Use Open Link vi and choose the TCP protocol Specify a link name such as 3000 machine domain This must be the address of the machine where the Mathematica kernel is running In Mathematica you use almost the same sequence of commands given in the previous section except that you must give option values consistent with the use of the TCP protocol In particular you have to use the LinkProtocol option In 1 link LinkOpen 3000 praline LinkProtocol gt TCP LinkMode gt Connect Out 1 LinkObject LabVIEW 4 2 In 2 LinkConnect link Out 2 LinkObject LabVIEW 4 2 Once again do not forget to close the link on both sides 80 Mathematica Link for LabVIEW In 3 LinkClose link Connections in Launch Mode Launch mode allows you to initiate a process from within another MathLink program A typical use of Launch mode is to have a Mathematica front end start the Mathematica kernel All the top level VIs of the MLStart 11b can open a link to the Mathematica kernel in Launch mode The purpose of Launch mode is to allow automation of the connection process Launch mode is an exception to the typical use of MLOpen in Launch mode a subsidiary process is initiated by a parent process In this instance the subsi
153. nce LabVIEW is specifically oriented toward data acquisition and instrumentation VIs often interact with hardware located either inside the computer acquisition boards for example or at remote locations connected via one or more communication interfaces Typically a LabVIEW program is required to interact with one or more specialized devices at run time Data acquisition and instrumentation applications often require various instruments to be synchronized with one another or with real world events such as triggers or user interaction The pseudo parallel structure of LabVIEW diagrams and their timing functions as well as their ability to make use of dedicated hardware timers allow VIs to simultaneously manage all of these events Mathematica Link for LabVIEW Practical Implementations In the opening paragraphs we briefly discussed different ways of using the Mathematica Link for LabVIEW package Here we will expand on this further Run Mathematica as a subprocess of LabVIEW Initially it may be easiest to visualize implementations where MathLink is used to run the Mathematica kernel as a subprocess of a LabVIEW application A particular computation step of your application may be easier to access or to implement in Mathematica than in LabVIEW Perhaps you need to access one of Mathematica s sophisticated functions or even the specialized domain specific capabilities of dedicated third party add on package Either way the
154. nce these memory management issues would have looked somewhat out of place in the LabVIEW environment the disown functions are automatically called whenever they are required in the CIN This means that you can get lists of any kind of data safely without concerning yourself with memory management Although it is clearly specified in the MathLink documentation that you must call MLDisownString after a call to MLGetString in LabVIEW you can read your string with MLGet String and forget the disown function This also applies to all of the functions that you use to get arrays of any type 67 3 Getting Started MLOpen Arguments The original prototype of MLOpen is MLINK MLOpen argc argv It is difficult to use that model to build a LabVIEW VI Actually the four arguments of MLOpen are the link mode the link protocol the link name and the link host Two menus help you select the mode and the protocol you want to use and two string controls specify the name and address of a remote partner MLOpen returns an integer in Link out The convention is that in the case of an error 0 will be returned instead of a NULL pointer Noninstallable VIs LabVIEW programs using MathLink are not installable in Mathematica Introduction to Error Management Error management in MathLink is a three step process First most MathLink functions return an integer value that can give you an indication of the result successful or not of the execution
155. nces be enclosed in quotation marks Here are examples e Correct PlotJoined gt True Frame gt True PlotLabel gt My Plot e Incorrect PlotJoined gt True Frame gt True PlotLabel gt My Plot AN IMPORTANT NOTE ABOUT ASPECT RATIO When using Generic ListPlot vi the last item in the Options box should always be AspectRatio gt 1 This ensures that the Mathematica image will completely fill the LabVIEW intensity graph If this step is neglected residual data may fill the unused portions of the intensity graph compromising the aesthetic quality of the visual presentation Feel free to experiment with your own data sets but remember that not all of the four ListPlot functions accept data with the same format 40 Experiment with Illustrate ListPlot vi to see how different data structures are used by various functions for data visualization Mathematica Link for LabVIEW ListPlot is the most versatile since it accepts data with two different formats For instance ListPlot yl y2 yn plots yl y2 yn at x values 1 2 n Yet you can specify custom x values using the alternative format for the data list ListPlot x1 y1 x2 y2 1x0 yn In Tutorial llb you will find a VI named Illustrate ListPlot vi This VI illustrates how different kinds of data structures are used by the different ListPlot functions Run this VI and consult its diagram ADVANCED SETTINGS Resolution The
156. nded to the Message log Appended to the session transcript Appended to the Menu log Appended to the Syntax log Not supported Not supported Not supported Not supported The INPUTPKT case is managed by the diagram shown in Figure 19 The INPUTSTRPRT case is processed similarly to the INPUTPKT case 91 4 Programming Mathematica Link for LabVIEW Figure 19 INPUTPKT processing EvaluatePacket The New session Check Box Check the New session check box to empty all the logs before the VI is run For a log set consisting only of the current Mathematica session you should enable this option whenever the Mathematica kernel is reinitialized Graphics Rendering When Mathematica graphics are returned to LabVIEW from the kernel the packet of types DISPLAYPKT or DISPLAYENDPKTs are sorted by Packet Parser vi After the packet DISPLAYENDPRT has been read the graphic is written in a temporary file by the MakeGraphTempFile vi from MLUtil 11b The temporary file generated by this VI is named mmagraphtemp and is located in the LabVIEW temporary folder The next step is to visually render the contents of this file As explained in the section Structure of the Link on page 13 it is necessary to interpret the PostScript information in order to generate a LabVIEW compatible bitmap version of the picture Rendering Mathematica graphics from inside a LabVIEW VI is a two step process First the PostScri
157. ne the Good PrimeQ vi diagram as illustrated in Figure 6 and run this VI Again before running the VI make sure that your kernel is not still connected to Bad PrimeQ vi In order to close the connection run Close All Links vi found in MLUtil 11b or accessible from the LabVIEW Tools menu Although Good PrimeQ viis similar to Bad PrimeQ vi because it uses an uninitialized shift register to manage the session the command it sends to the kernel is very different One evaluation only is sent PrimeQ random numbers 35 Figure 6 The Good PrimeQ vi diagram 3 Getting Started Elapsed Time yoonn00i000000000 M 0 2 p 220 0 0 i hiii A While loop introduced to use an uninitialized shift register E ata set size maji OF fraen Ve 1 vi Fie B n 7 The list is concatenated in the For loop HA Eike Fas G HEE 0ug0do0 o0dodo0 o0dad o0ddo0 gdgdo ogd o g0do o0 ogdo 0 gd 0 g0do g0 og do g d 0 E U32 Because there are fewer MathLink transactions Good PrimeQ vi is more efficient than Bad PrimeQ vi however more effort is required to properly format the command string In order to quit again run Close All Links vi found in MLUtil 11b or accessible from the LabVIEW Tools menu Logs Description Most packets received by LabVIEW are recorded in the log clusters If you are unfamiliar with MathLink you only need to know that data are sent over the link wrapped
158. nfinite loop is necessary it is possible to eliminate the timeout parameter by setting its value to with the LabVIEW built in constant Link Monitor vi should not be used between MLOpen and MLConnect because it can be used only on connected links Figure 16 The Link Monitor vi diagram Error Management Tools Mathematica Link for LabVIEW uses globals and custom error manager VIs to track and control error processing In this section we will discuss the integrated error handling capabilities of Mathematica Link for LabVIEW along with a short introduction to potential error sources Mathematica Link for LabVIEW Four Error Types and the ErrorOffset gbl Global Variable Four kinds of errors may occur in Mathematica Link for LabVIEW e Mathematica errors e MathLink errors e Mathematica Link for LabVIEW errors e LabVIEW errors Mathematica errors are easy to handle since they always generate messages Mathematica is extremely robust and error messages are automatically generated The task at hand is to collect these messages and dispatch them accordingly see the Packet Parser vi section on page 89 MathLink errors are more subtle most MathLink functions simply return a value of zero when a problem occurs After this error signal you must use MLError to identify the error code Special error codes that do not conflict with MathLink nor with LabVIEW have been introduced to tag Mathematica Link for LabVIEW errors Fi
159. ng problems Mathematica is a general purpose system for doing mathematics It is a rich programming language that allows a problem to be interactively explored in many different ways Its underlying architecture is based on transformation rules and pattern matching which in turn provides powerful symbolic capabilities Often Mathematica programs comprise a large set of definitions or rules that are applied at evaluation time In most cases the evaluation of a Mathematica program will last no longer than just a few seconds When an evaluation is running in the kernel you still can interact with the front end but you cannot start another evaluation until the one that is currently running is completed However it is possible to connect your front end to several kernels simultaneously You can for instance assign the evaluation of cells containing complex commands to a remote kernel running on a system with a fast CPU while you keep your local kernel for less intensive interactive evaluations A Mathematica session is a series of inputs and the corresponding outputs returned by a kernel Conversely many LabVIEW programs are designed to run indefinitely until you stop them Due to the data flow model many tasks occur simultaneously during execution It is the programmer s responsibility Mathematica Link for LabVIEW to prioritize tasks through time delays so that there is adequate resources for higher priority operations Moreover si
160. nkMode gt Listen Out 1 LinkObject Ilkds 2 2 In 2 LinkConnect link Out 2 LinkObject lkds 2 2 You cannow run Simple Data Server vi Select the type of the data you wish to send on the link using the ring control note that the corresponding control becomes active Set the value of the data in the control and click the Send Data button You can now return to Mathematica and try to collect the data that you have just sent A good practice is to make sure that something is ready to be read before you actually attempt to read it LinkReadyQ is the query command that serves this purpose In 3 LinkReadyQ link Out 3 True True should be returned Since something is waiting you just have to read it In 4 LinkRead link Out 4 0 2 0 03 I In place of the output shown in this example you should see the data you sent You should now try to send several pieces of data at once from the LabVIEW side Select the data types you wish to test and click the Send Data button as many times as you want Then go back to the Mathematica notebook and repeat the previous sequence of instructions Be sure that there is something to read before reading it 99 4 Programming Mathematica Link for LabVIEW In 5 If LinkReadyQ link LinkRead link Print The link is empty Out 5 1 In 6 If LinkReadyQ link LinkRead link Print The link is empty Out 6 2 n If LinkReadyQ link LinkRead link
161. node items of the graph where the data are displayed 195 5 Reference Guide Globals ErrorOffset gbl vit Oftset ErrorOffset gbl This global variable is used to shift MathLink and Mathematica Link for LabVIEW error codes into the area reserved for user defined error codes The valid data range for user defined error codes is 5000 to 9999 See the General Error Handler vi documentation for more details on this topic Error code offset Set this control to a different value to avoid if you notice conflicts with other user defined error codes used by other LabVIEW applications MLConstants gbl MLINE A MLConstants gbl The constants defined in the mathlink h header file are reported here so that they can be accessed by Mathematica Link for LabVIEW They are the type codes packet codes error codes and corresponding error messages Note that in the mathlink h file error messages are not defined but are only mentioned as comments to error codes Error messages should be retrieved by MLErrorMessage in a MathLink program However since having a hard copy of these messages in LabVIEW allows errors to be handled in a way more consistent with LabVIEW programming style this MathLink programming guideline has been violated in this distribution Type codes The various integers codes of the elements in a MathLink data stream 116 Error codes MathLink integer error codes as they are defined in the mathlink h file 133 Pac
162. nt a few simple yet practical examples of how various components from the package can be applied to real world data acquisition analysis and control system challenges Process Monitoring with MathLink Earlier in this chapter we discovered how to call LabVIEW VIs from inside a Mathematica notebook As you may recall this involved MathLink VI Server vi onthe LabVIEW side and a custom Mathematica package called VICLient m Unfortunately the functions provided in the VICLient m package do not permit direct real time process monitoring using a remote LabVIEW application This is because the CallByReference and CallInstrument functions can only read LabVIEW data after completion of the VI run However with modest effort it is not difficult to customize an existing LabVIEW application to make it capable of passing data to Mathematica The model we will use to demonstrate the technique is based on Temperature System Demo vi one of the numerous examples provided with LabVIEW The original VI can be found in the apps directory in tempsys 11b The modified MathLink version of this VI isnamed MathLink Temperature vi You can find a copy of this VI in Tutorial 1lb OPERATION OF MATHLINK TEMPERATURE VI After opening MathLink Temperature vi you may notice that its front panel is identical to the original The VI s diagram is shown in Figure 26 To make this demonstration as simple as possible no option has been provided for setting conn
163. of elements in each dimension my A n Heads The Mathematica function name describing the data structure Example the heads of Complex a1 b1 Complex a2 b2 are List ieolComplex eol Depth The array depth Example 2 for a 3 x 3 matrix 151 5 Reference Guide MLGetDoubleList vi Link in Link out Double list error in no error error out MLGetDoubleList vi MLGetDoubleList vi reads a list of real numbers from Link in and assigns it to the Double list indicator The Value indicator returns a nonzero value if the operation was successful of zero if an error occurred In this case the error can be identified with MLError Warning The user does not have to call MLDisownDoubleList after using this VI since this step is achieved in the CIN DEL Double list The list of doubles read on the link MLGetFunction vi Argument count Link in Link out error in no error Function error out MLGetFunction vi MLGetFunction vi reads a Mathematica function name and argument count from Link in See the MathLink documentation for more details Warning The user does not have to call MLDisownSymbol after using this function as specified in the MathLink documentation since this is achieved in the CIN Function The name of the function read from Link in Argument count The number of arguments of the function read from Link in 152 Mathematica Link for LabVIEW MLGetInteger vi
164. on Link functions and are designed for users with only a minimal familiarity with MathLink They provide ready made solutions for a variety of standard applications MathLink VI Server vi This VI is a bridge between MathLink and the various VIs of the LabVIEW VI control library A number of Mathematica functions have been designed that are strict Mathematica equivalents of these VIs Thus you can use functions such as OpenVIRef OpenPanel RunVI and 13 1 Introduction What is Mathematica Link for LabVIEW others to operate your LabVIEW applications These applications can run either on the same computer or on two different computers linked over a network Kernel Evaluation vi This VI passes a string of Mathematica commands in the usual Mathematica syntax to the kernel for evaluation and returns the results to LabVIEW You need to specify the expected data type for the result from among a finite number of data types Boolean Integers Real Complex Strings and lists and matrices of all these types The result of the evaluation is returned on the indicated connector of the VI Kernel Evaluation vi has high level functions to manage all aspects of Mathematica sessions such as printed messages error messages etc You can use it as a general purpose interface to Mathematica functions within the diagrams of your LabVIEW applications Mathematica Graphics Generators Four VIs are provided to make Mathematica graphical function
165. on numbers from the link This VI is based on MLGetDoubleArray vi Warning Since there is no MathLink function to verify that the incoming array fits a matrix of real numbers data structure it is your responsibility to ensure that the array fits the data structure when using this VI Inconsistent incoming data read by this VI can lead to a MLEGSEQ MathLink error double matrix The matrix of double precision numbers read from the link GetIntegerMatrix vi Link in Link out integer matrix error out error in no error GetiIntegerMatrix vi GetIntegerMatrix vi reads a matrix of integers from the link This VI is based on MLGetIntegerArray vi Warning Since there is no MathLink function to verify that the incoming array fits a matrix of integers data structure it is your responsibility to ensure that the array fits the data structure when using this VI Inconsistent incoming data read by this VI can lead to a MLEGSEQ MathLink error integer matrix The matrix of integers read from the link 140 Mathematica Link for LabVIEW GetLongDoubleComplex vi Link in Link out CET long double complex error out GetLongDoubleComplex vi error in no error GetLongDoubleComplex vi reads a complex number from the link This VI is based on MLGetLongDoubleArray vi Warning Since there is no MathLink function to verify that the incoming array fits a complex number data structure it is your responsibility to ensure
166. op for a hypothetical experiment e Choose acquisition parameters then make a data acquisition run from within a Mathematica notebook e Analyze process and view the data returned by the instrument interactively using advanced Mathematica functions e Use the results from your analysis to compute a new set of values for the acquisition parameters e Return to the first step After the optimal experimental conditions are determined you may want to take additional steps such as 10 Mathematica Link for LabVIEW e Saving your Mathematica notebook so the entire experiment can be recreated and duplicated in the future e Developing a stand alone LabVIEW VI with hard wired acquisition parameters for 100 repeatability e Extending the native LabVIEW functionality of your stand alone VI by calling advanced Mathematica data processing graphing and file export capabilities This hypothetical workflow exposes some of the opportunities offered by the Link but the details and requirements of your own applications may introduce a completely different set The key is to exploit the relative strengths of the Mathematica and LabVIEW user interfaces and then realize the combined productivity benefits of both Programming and application examples illustrating all of the practical implications noted above are included with the Mathematica Link for LabVIEW package Programming examples are introduced in the Getting Started and
167. or long double complex matrix The matrix of complex numbers read from the link GetLongDoubleMatrix vi Link in Link out HA long double matrix error in no error r F error out GetLongDoubleMatrix vi GetLongDoubleMatrix vi reads a matrix of extended precision numbers from the link This VI is based on MLGetLongDoubleArray vi Warning Since there is no MathLink function to verify that the incoming array fits a matrix of real numbers data structure it is your responsibility to ensure that the array fits the data structure when using this VI Inconsistent incoming data read by this VI can lead to a MLEGSEQ MathLink error long double matrix The matrix of extended precision numbers read from the link 142 Mathematica Link for LabVIEW GetLongIntegerMatrix vi Link in Link out long integer matrix error out GetLonglilntegerMatrix vi error in no error GetLongIntegerMatrix vi reads a matrix of integers from the link This VI is based on MLGetLongIntegerArray vi Warning Since there is no MathLink function to verify that the incoming array fits a matrix of integers data structure it is your responsibility to ensure that the array fits the data structure when using this VI Inconsistent incoming data read by this VI can lead to a MLEGSEQ MathLink error long integer matrix The matrix of long integers read from the link GetStringList vi Link in Link out string list error out error in
168. or vi 86 MLClose vi 56 127 MLComm llb 24 71 74 125 MLConnect 84 MLConnect vi 127 MLConstants gbl 196 MLDisown functions 67 MLEndPacket vi 127 MLError 83 85 MLERROR Ident vi 188 MLError vi1 86 128 MLErrorMessage vi 128 MLERRORS ctl 198 MLFast llb 74 136 MLFlush vi 129 MLGetDouble vi 150 MLGetDoubleAtrray vi 151 MLGetDoubleList vi 152 MLGetFunction vi 152 MLGetInteger vi 153 MLGetIntegerArray vi 154 MLGetIntegerList vi 155 MLGetLongDouble vi 155 MLGetLongDoubleArray vi 156 MLGetLongDoubleList vi 157 MLGetLongInteger vi 157 MLGetLongIntegerArray vi 158 MLGetLongIntegerList vi 159 MLGetNext vi 130 MLGets llb 24 74 149 MLGetString vi 155 159 MLGetSymbol vi 150 159 MLGetType vi 131 MLINK 67 MLNewPacket vi 132 MLNextPacket 90 MLNextPacket vi 132 MLOpen 68 MLOpen 62 68 75 84 MLOpen vi 133 MLPACKET Ident vi 189 MLPACKETS ctl 198 MLPost 13 38 39 47 92 Link in 93 MLPost Init vi 189 MLPutDouble vi 160 MLPutDoubleArray vi 161 MLPutDoubleList vi 162 MLPutFunction vi 162 MLPutInteger vi 160 162 MLPutIntegerArray vi 163 MLPutIntegerList vi 164 MLPutLongDouble vi 164 MLPutLongDoubleArray vi 165 MLPutLongDoubleList vi 166 MLPutLongInteger vi 166 MLPutLongIntegerArray vi 167 MLPutLonglIntegerList vi 168 MLPutMessage vi 133 MLPuts llb 24 74 159 MLPutString vi 168 MLPutSymbol vi 169 MLReady 83 MLReady vi 129 134 MLStart llb 23 81 169 MLType
169. ormal discussions of the programming examples included with Mathematica Link for LabVIEW The next chapter will look more closely at the individual VIs included in the package 120 Mathematica Link for LabVIEW Figure 32 The Khepera robot 121 5 Reference Guide This chapter provides in depth reference material for Mathematica Link for LabVIEW developers Each and every component sub VI that is all the library VIs found in the dev subdirectory of the LabVIEW user 1lib MathLink directory plus all of the MLStart 11b VIs are documented in a style consistent with the LabVIEW reference manuals Different sections correspond to the different libraries In addition the final section of this chapter documents the VIClient m package is some detail Most VIs of the distribution have a common set of controls and indicators Since it would be redundant to reproduce the description of these common objects wherever they appear these common items will be discussed first As already mentioned page 67 all VIs used to conduct MathLink operations have a Link in control to receive the link ID number This number identifies the link over which all data transactions will be performed There is also a Link out indicator which always has the same value as Link in This indicator can be used to create artificial data dependencies that control the execution sequence of the VI diagram Refer to the LabVIEW documentation fo
170. ossible errors resulting from the conversion of the flattened data to numerical data Control2bin vi Link in Link out l Inputs error in no error error out Control2bin vi Control2bin vi is used to flatten incoming control values to pass them to Call Instrument vi This VI is a subVI of MathLink VI Server vi Peal Inputs An array of clusters containing a control name a type descriptor and flattened data You can get the type descriptor and the flattened data from the Flatten to String function This cluster will be wired to the connector labeled inputs of the Call Instrument vi 177 5 Reference Guide Delay Settings vi Hee Delay to quit Hih Delay to launch beer Delay to evaluate Delay Settings vi Delay Seitings vi is used to set up the three delays introduced to schedule Kernel Evaluation vi operations If it appears that the default values of these controls are adaptated to your configuration edit the VI to change the default values of the controls See the on line help of each control for more details Delay to evaluate The maximum time allowed to the kernel for evaluating a command Delay to launch The time that Mathematica needs when it is launched before it can reply to external requests Delay to quit This delay is the time necessary to the kernel when it quits the current link to be available for a new connection If this delay is too short the kernel file will not be found 178 Mathem
171. ou want to generate Graph The graph generated by Mathematica You can wire this data set to an intensity graph or to the customized type definition GraphicsWindow ctl Color display can be controlled by wiring the color palette to the corresponding attribute node Color palette The color palette of the picture These data are wired to the corresponding attribute node items of graph MLPost link out Same as MLPost link in Use it to sequence MLPost operations Message The messages returned by the kernel All the messages generated during the Mathematica session are returned here 171 5 Reference Guide Generic Plot vi MLPost link in MLPost link out Link in Link out Command Graph Color palette Message error out Resolution error in no error Timeout 60s Generic Plot vi Generic Plot vi can be used to generate any kind of Mathematica graphics The Command box is used to type the Mathematica command to generate the graphics just as you would type it in a Mathematica notebook See your MathLink for LabVIEW documentation for more details and your Mathematica documentation for graphics command reference Resolution Graphics dimensions Graphics are returned in a square window Resolution is the size of the square side expressed in the number of pixels Timeout 60s The maximum time allowed to Mathematica for generating the graphics MLPost link in The number of the link to MLPost Comman
172. pes MLTKSTR Mathematica string MLTKSYM Mathematica symbol MLTKINT integer MLTKREAL real number MLTKFUNC composite expression MLTKERROR error getting type 131 5 Reference Guide MLNewPacket vi Link in 2 ae out error in no error error out MLNewPacket vi MLNewPacket vi discards the remaining data in the expression currently being read from Link in MLNewPacket vi works even if the head of the current top level expression is not a standard packet type MLNewPacket vi does nothing if you are already at the end of a packet MLNextPacket vi Link in Link out MLPACKET error in no error error out MLNextPacket vi MLNextPacket vi reads the head of the expression currently waiting to be read form Link in It returns an integer code corresponding to the packet type See the MathLink h file for the definition of the integer codes If the head of the current expression does not match any of the defined packet types MLNextPacket vi returns zero Warning The integer packet code is returned simultaneously on the Value and the long integer elements of the CIN output cluster It is read on Value for error checking and the value returned on long integer is converted into a packet type by MLPacket Ident vi Packet code The integer code of the packet type Zero is returned when the packet head is not defined MLPACKET The packet types are defined in the mathlink h file The most common packets are these I
173. point and PID tuning parameter changes The dynamic effects of these user initiated changes are reflected in the scrolling process response graph that dominates the panel 113 Figure 29 The PID Control Demo vi front panel 4 Programming Mathematica Link for LabVIEW ifs PID Control Demo vi File Edit Operate Tools Browse Window Help T are PID Control Demo a Gain ree eh Setpoint POETI Output Link Error Sim Loop Time sec OPERATION OF THE PID CONTROL DEMO VI Open the PID Control Demo vi from the LabVIEW Tools menu Run the VI and observe the graph as the output is manipulated to bring the process variable up to the Setpoint value Experiment with different setpoints then try changing the Process Characteristics on the left and the PID Parameters on the bottom of the panel When you are finished experimenting press Stop in the lower right corner Since Mathematica must process both the simulation and control calculations on each loop iteration there is a limit to how quickly the control loop can run If you find that you are encountering MathLink errors as revealed by the Link Error indicators on the panel simply increase the Loop Time sec parameter 114 Mathematica Link for LabVIEW PID CONTROL DEMO VI DIAGRAM The PID Control Demo vi block diagram see Figure 30 is based on a state machine structure Kernel Evaluation vi introduced previously in Chapter 3 is responsible for al
174. pt expression of the graphics has to be converted to a bitmap form Second the bitmap description of the graphics must be read into the VI front panel To accomplish this second step a temporary LabVIEW compatible bitmap is generated and read in for display on the LabVIEW front panel The entire graphics file processing chain is handled by Graphics Viewer vi and its subVIs If the mmagraphtemp file cannot be found an empty picture is displayed and nothing more is done Otherwise a subVI named Pictify vi is called This VI manages the MLPost operations In particular it detects whether or not MLPost has been launched on the 92 Mathematica Link for LabVIEW basis of the value of MLPost Link in A value of zero means that the application has not yet been launched The other arguments of this VI are the name of the bitmap temporary file its default value is mmapicttemp and the dimensions the number of columns and rows of the bitmap graphic Once the bitmap file has been generated the next step is to read it This is achieved by Read Bitmap vi which calls a particular function implemented in MathLinkCIN vi This is the only function of this CIN that is not a true MathLink function One of the arguments passed to Read Bitmap vi is Link in which is used mainly to allow sequencing of graphic processing steps through data dependency Note however that no MathLink operations are conducted here The number of lines and column
175. ptions Tutorial b FI Control Demo Utilities d Readers interested in calling LabVIEW VIs from inside a Mathematica notebook are directed to the hands on tutorials installed with the Mathematica files After Mathematica Link for LabVIEW has been installed you can access the tutorials from the AddOns section of the Mathematica Help Browser see Figure 3 Figure 3 Accesssing the Hands on Tutorials from the Mathematica Help Browser 3 Getting Started lel Es Ea Help Browser Hands On Tutorial 1 Back Hide Categories Built in Functions Add ons The Mathematica Book Getting Started Demos Other Information Master Index Working with Add ons Standard Packages MathLink Library Getting Started e Programming e viclent m Reterence i Hands On Tutorial 1 i Hands On Tutorial 2 Renee eek See ands On Tutorial 3 YI Client Palette Hands On Tutorial Part 1 Alternatively you can find the raw tutorial notebook files HandsOn_Partl1 nb HandsOn_Part2 nb and HandsOn_Part3 nb in the following Mathematica subdirectory AddOns Applications LabVIEW Documentation English Note This material can also be found in the LabVIEW file system inside the user lib MathLink LabVIEW Documentation subdirectory If you have any difficulty locating and running these items review the previous Installation chapter to ensure that the Mathematica Link for LabVIEW components h
176. r error out wo ed PutDoubleComplex vi can be used to write a complex number over the link double complex The complex number sent over the link PutDoubleComplexList vi Link in Link out double age list B error in no error error out opm D PutDoubleComplexList vi can be used to write a list of complex numbers over the link tpe double complex list The list of complex numbers sent over the link PutDoubleComplexMatrix vi Link in Link out double hve matrix error in no error error out PutDoubiecomplexkiatrix vi PutDoubleComplexMatrix vi sends a matrix of complex numbers over a link feoe double complex matrix The matrix of complex numbers sent over the link PutDoubleMatrix vi Link in Link out double matrix error in no error error out PUD oubleMairixvi PutDoubleMatrix vi sends a matrix of doubles over the link iben double matrix The matrix of doubles sent over the link 146 Mathematica Link for LabVIEW PutIntegerMatrix vi Link in Link out ed matrix 7 error in no error error out Putin ieaermaninv PutIntegerMatrix vi sends a matrix of integers over the link integer matrix The matrix of integers sent over the link PutLongDoubleComplex vi Link in Link out long double 5 eon error in no error error out a os PutLongDoubleComplex vi sends a complex number over the link long double complex The complex number sent over the link PutLongDoubleComplexList vi Link in Link o
177. r by way of coercion dots on the diagram Type casting can be kept to a minimum by eliminating coercion dots wherever possible Elementary Data Type Conversion Table The following table shows the most natural correspondences between the elementary data types of the three languages Mathematica MathLink LabVIEW Integer short integer integer long I8 116 132 U8 U16 U32 integer Real double long double SGL DBL EXT Complex Mathematica expression CSG CDB CXT Rational Mathematica expression SGL DBL EXT String string abc Symbol string abc In this version of Mathematica Link for LabVIEW extended precision numbers are converted to double precision numbers and word integers 16 bit format are converted to long integers 32 bit format for MathLink transactions While this should prove adequate for the majority of practical implementations future versions of the Link may introduce additional data formats Peculiarities of Mathematica Link for LabVIEW Every effort was made during the development of Mathematica Link for LabVIEW to retain 100 compatibility with the original MathLink functions However differences between LabVIEW and the C language make minor adaptations of some MathLink features 6 6 Mathematica Link for LabVIEW unavoidable Specifically MathLink VIs differ from their C counterparts with respect to link identification the way they deallocate memory and the way they report function values MLOpen
178. r in the next section SIMPLE DATA CLIENT VI DIAGRAM Now let us turn our attention to this VI s diagram The first step involves initializing the indicators attributes This takes place in the sequence structure on the left of Figure 25 In frame 2 of this sequence the link is opened and connected When these steps are complete execution proceeds to the main loop Here execution is locked in a link 105 Figure 25 Simple Data Client vi diagram 4 Programming Mathematica Link for LabVIEW scanning loop where continuous calls are made to MLReady This loop prevents the VI from hanging by blocking read attempts until the other partner has sent something over the link When link data is detected execution proceeds to the next step The scanning rate depends on your application You can use the vertical slide to set a variable scanning rate manually Each time MLReady vi is executed i e each time the scanning loop is executed the picture displayed on the Copyright Notice vi front panel is updated You can visualize the scanning frequency by observing the changes to this picture fi eee ec ae im a abc Disabled a a RA KEEKEEKE Pee ae O O Fao ey OH aloo SE eet l Disabled Strin on Symbol Disabled Symbol Indicator visibilit p j 5 aca F penei b String na H When data are received the scanning loop terminates and the MLGetType instruction is executed The nature o
179. r more information about controlling data flow through artificial data dependency Most MathLink functions return an integer value indicating the error status of the operation nonzero values indicate that everything was OK This value is returned when applicable in a dedicated indicator named Value Consult The Mathematica Book and The MathLink Reference Guide for more details about MathLink error codes Finally as noted on page 68 Mathematica Link for LabVIEW conforms to the classical LabVIEW error management conventions VIs have error in and error out clusters that are used to report errors to the error handler VI These clusters are standard front panel objects and 5 Reference Guide can be accessed through the Arrays and Clusters submenu of the default view Next we will look at descriptions for these common elements Keep in mind that these items will not be repeated for each VI in which they appear Consult LabVIEW s on line documentation for a complete description of the error in and error out clusters if you are unfamiliar with their usage Link in Link identifier Value A nonzero value indicates that no error occurred Link out The link over which the function name was received same as the input link This is used to create data dependency between MathLink VIs Mathematica Link for LabVIEW VIs can all be accessed with custom palettes and views The top level palettes are
180. r vi There are also some lower level utilities in this library that can be useful when developing custom MathLink applications Tutorial and Example VIs A variety of example VIs are included along with the core Mathematica Link for LabVIEW VIs These examples are intended to demonstrate the low and medium level VIs in action Several examples can be found in Tutorial 11b located at the top level of the LabVIEW user 1lib MathLink directory Additional examples including applied graphics utilities a simple PID control demo a mobile robotic control example and a sophisticated hybrid workflow demo can 74 Mathematica Link for LabVIEW be found inside the Extras subfolder of the LabVIEW user 1lib MathLink directory The examples will be discussed in more detail at the end of this chapter Although the locations of the various files within the LabVIEW file hierarchy are given here it should be noted that the VIs can also be easily accessed from the LabVIEW Tools menu or from MathLink tab of the User Libraries located at the bottom of the LabVIEW Functions palette For additional information about the structure and organization of Mathematica Link for LabVIEW components refer to Chapter 3 Getting Connected Open Link viinTutorial 11b isa very simple program that conducts a MathLink session It opens a link connects to the other partner and then closes the link not a very sophisticated or useful VI but one that embodies a basic
181. rch strategy to determine the most likely target paths 19 2 Installation However an inappropriate path is sometimes selected if several instances of Mathematica or LabVIEW are installed on the target PC or if Mathematica and LabVIEW are installed on different PCs drives or drive partitions Be sure to verify and if necessary specify alternate paths before initiating the installation step 5 Follow the instructions provided by the installer and review the online installation notes for additional information and last minute changes 6 A Mass Compile option has been added to the exit page of the VI based installer Click the Mass Compile button if you would like to update the main toolkit components for the version of LabVIEW you are running Note to minimize the time required some secondary Link components are not updated by the Mass Compile function 7 Register your copy of Mathematica Link for LabVIEW by selecting the On line Registration option on the Exit page of Install vi or by filling in the Application Library Registration Form accessed from the LabVIEW item in the Add ons section of the Mathematica Help Browser see next subsection 8 To finish the installation quit and restart LabVIEW When LabVIEW restarts you will have direct access to the Link components through the Function and Control palettes Also you will discover that new MathLink items have been inserted in the LabVIEW Help and Tools menus REBUI
182. re the only functions that use the control and indicator lists of Instrument objects CallByReference link instrument or alternatively CallInstrument link instrument will load run and release the VI if it is not in memory yet Otherwise it is only run and you have to release it after use with a CloseVIRef or ReleaseInstrument function Verbose is an option for OpenVIRef PreloadInstrument CloseVIRef ReleaseInstrument OpenPanel ClosePanel RunVI RunInstrument and CallByReference CallInstrument It specifies whether the acknowledgment message read from the link should be displayed If a large number of such instructions are processed displaying messages can hinder the results of operations 206 Bibliography 1 Gayley T A MathLink Tutorial Wolfram Research Inc Technical Report 1994 Available as MathSource item 0206 693 2 National Instruments LabVIEW 4 0 Tutorial 1996 3 National Instruments LabVIEW User Manual versions 4 0 to 6 1 1996 2002 4 Wagner D B MathLink mode The Mathematica Journal 6 44 57 1996 5 Wolfram Research Inc The MathLink Reference Guide Technical Report 1993 6 Wolfram S The Mathematica Book 3rd ed Wolfram Media Cambridge University Press 1996 7 Shinskey F G Process Control Systems Applications Design and Tuning 4th ed McGraw Hill Inc 1996 8 Ritter D J LabVIEW GUI Essential Techniques 1st ed McGraw Hill Inc 2002
183. represented in Figure 33 Figure si The control and function palettes of Fr lock f iF 7 HE Pau ms gt l mm the MathLink view 124 Mathematica Link for LabVIEW Figure 34 Mathematica i MathLink MathLink Link for LabVIEW main control and function palettes MLEAROA PACKETS 71 z TEP E PPE MLComm Ilb I gt HLComm is MHLIHE E 125 5 Reference Guide VIs MathLinkCIN vi Input cluster E oun cluster MathLinkCIN vi MathLinkCIN vi is the interface to the C code This VI is not intended to be used directly This VI is the only one of the distribution containing a CIN The input and output clusters have the same structure They provide all possible kinds of data to be used by MathLink functions as arguments or returned by these functions The only argument specific to this VI is the MLFunction name which is used by the CIN to properly read all its arguments Warning Integers of any type are passed in the long integer field See InputClusterTemplate ctl and OutputClusterTemplate ctl on page 134 for a description of the input and output clusters MLClear Error vi Link in o out error in no error error out MLClearError vi MLClearError vi clears any error on the Link in and reactivates the link if possible This function can be used at the end of a complicated operation If an error is detected you can proceed to corrective action if possib
184. rix of booleans from the link Since there are no MathLink functions for transferring arrays of booleans the matrix is read as a compound Mathematica expression List List elem 1 elem 2 elem n In two nested For loops the result of MLGetSymbol vi is compared to True and the result is displayed in the boolean indicator Warnings 1 If a symbol other than True or False is read from the link False is returned You have to make sure that True and False are the only possible symbols sent over the link before calling GetBooleanMatrix vi 2 Due to the structure of this VI its performance is limited If you need to send a large number of booleans you should probably try to send them in a numerical format and convert them in LabVIEW later TF boolean matrix The matrix of booleans read from the link GetDoubleComplex vi Link in Link out double complex L error out GetDoubleComplex vi error in no error GetDoubleComplex vi reads a complex number from the link This VI is based on MLGetDoubleArray vi Warning Since there is no MathLink function to verify that the incoming array fits a complex number data structure it is your responsibility to ensure that the array will fit the data structure when using this VI Inconsistent incoming data read by this VI lead to an MLEGSEQ MathLink error double complex The complex number read from the link 138 Mathematica Link for LabVIEW GetDoub
185. rld True LinkWrite link Symbol True LinkWrite link 2 5 3 I True Note that complex numbers are actually sent as functions This is consistent with their internal representation in Mathematica which you can display with this command 104 Mathematica Link for LabVIEW In 9 FullForm 2 5 3 I Out 9 FullForm Complex 2 5 3 Note however that this behavior cannot be generalized for sending any kind of function To demonstrate try this In 10 LinkWrite link Sin x True The function was read but nothing appeared on the VI front panel as a result It is not identified as a readable data type in this VI Instead you are notified that something arrived that could not be handled by the data client As an interesting experiment execute this command In 11 LinkWrite link Sin Pi True Can you explain why the VI correctly read this expression If you are unable to explain this but are intrigued by this behavior refer to the sections related to expression evaluation in The Mathematica Book by Stephen Wolfram Finally you will want to close the link Type this command and observe the result In 12 LinkClose link Notice the effect this last step has on the VI front panel Obviously a problem was detected since an error message is presented You will also notice the VI stops executing very soon after you acknowledge this error message We will investigate the reasons for this behavior furthe
186. rogramming techniques in various practical contexts 73 4 Programming Mathematica Link for LabVIEW Low Level VIs The low level VIs can be found in the dev subfolder of the LabVIEW user lib MathLink directory They are organized into lb libraries and are grouped as follows e MLComm 11b This library contains all MathLink functions devoted to link management the functions that do not transfer data MathLinkCIN vi is also located in this library e MLFast 11b This library is a collection of higher level functions used to transfer common data structures for which no MathLink function is available including functions to transfer booleans lists of strings matrices of complex numbers etc e MLGets 11b This library contains all MathLink functions used by LabVIEW to read data from the link such as MLGet String MLGetLongInteger etc e MLPuts 11b This library contains all MathLink functions used by LabVIEW to send data over the link such as MLPut String MLPutDouble etc e MLUtil 11b This library is a collection of utilities used by many of the other VIs in this distribution Medium Level VIs The medium level VIs can be found in MLStart 11b at the top level of the LabVIEW user lib MathLink directory Four of the VIs in this library can be used immediately as top level VIs as you start working with Mathematica Link for LabVIEW These are Kernel Evaluation vi Generic ListPlot vi Generic Plot vi and MathLink VI Serve
187. rrors a series of consecutive errors will adversely affect the integrity of the controller If MathLink errors are degrading performance try increasing the value of Loop Time sec until errors are no longer detected Informal testing suggests the default setting of 1 5 seconds should be more than adequate for the majority of PCs Admittedly this is a very simple example Mathematically speaking there is nothing here that couldn t be implemented directly with native LabVIEW formula nodes However one advantage of processing the calculations using MathLink functions rather than LabVIEW formula nodes is that you have the option of modifying the equations interactively at run time This offers a greater degree of interactivity than standard formula node methods which require you to stop the VI in order to edit the contents of the node This simple example suggest opportunities for more sophisticated simulation and control strategies and many interesting variations could be explored simply by extending this basic framework Furthermore advanced Mathematica library functions and add on packages can be introduced into the LabVIEW workflow Using this basic framework you can readily experiment mathematically sophisticated simulation and control strategies that lie beyond LabVIEW s inherent mathematical capabilities Advanced Topics and Examples By now it should be clear that Mathematica Link for LabVIEW is a flexible package that offers
188. s available to LabVIEW Generic ListPlot vi displays a graphical representation of sets of data Generic Plot vi is used to visualize from within LabVIEW graphics returned by Mathematica commands Display Bitmap vi is similar in function to Generic Plot vi but uses Mathematica graphic functions to generate a BMP rather than a PICT file Generate Graphic File vi illustrates how images generated in Mathematica can be exported to one of several different image file formats Development Tools A number of VIs can help you build your own MathLink applications They combine the action of several MathLink functions in ways frequently encountered when developing MathLink applications Data Transfer VIs Thirty VIs are provided to transfer the most commonly used data structures mainly lists and matrices of all kinds They are documented and their source code is accessible so they can be a basis for building new VIs to transfer other data structures that have not yet been implemented 14 Mathematica Link for LabVIEW Error Handling VIs Mathematica Link for LabVIEW follows the LabVIEW error cluster scheme for managing MathLink errors All the VIs have Error in and Error out clusters A MathLink Error Manager vi based on General Error Handler vi is provided to identify MathLink errors and take the appropriate corrective action when possible MathLink VIs Forty three of the most commonly used MathLink functions are imple
189. s of the picture as well as the path to the bitmap file are other required arguments The picture is returned as a matrix of color values along with the color palette for the image The picture is displayed in a custom intensity graph named GraphicsWindow ctl1 found in MLStart 11b The information returned by Read Bitmap vi in the Color palette cluster must be wired to the corresponding items of an intensity graph property node Both temporary files that were generated in the course of generating the graphic are deleted after being processed Other Graphics Examples The notes above pertain specifically to Generic Plot vi and Generic ListPlot vi the two primary graphics examples found in MLStart 11b These examples take advantage of MLPost a stand alone executable that converts Mathematica s PostScript files into bitmap files While MLPost is perhaps the easiest way to display Mathematica graphics on a VI front panel other graphic options are available For example Mathematica graphics export capabilities can be accessed directly using standard Mathematica commands as illustrated by Generate MM Graphics File viand Display BMP vi These and other graphics examples can be found in the Extras subdirectory of LabVIEW user 1ib MathLink folder or alternatively can be accessed via the LabVIEW Tools menu or through the MathLink tab on the Functions palette 93 4 Programming Mathematica Link for LabVIEW Commented Programming E
190. set It calls one of the Mathematica ListPlot functions ListPlot ListContourPlot ListDensityPlot ListPlot3D according to the value of the Plot type control See your Mathematica documentation for a detailed description of these functions Warning To avoid sending an empty array over the link if the Data control is empty it is automatically filled with 0 0 before being sent 170 E AE E 2 E Mathematica Link for LabVIEW Data The data to plot Their format depends on the function you select ListPlot accepts data as either a list or an n x 2 matrix The other three functions require the data to be passed as a matrix of heights See the Mathematica book for details Warnings 1 If you attempt to send an empty matrix Generic ListPlot vi will automatically fill it with 0 0 to ensure normal behavior of the data transfer over the link 2 If you send any matrix having invalid dimensions a Resolution Graphics dimensions Graphics are returned in a square window Resolution is the size of the square side expressed in the number of pixels Timeout The maximum time allowed to Mathematica for generating the graphics MLPost link in The number of the link to MLPost Options The list of options The series of options should be comma delimited but not enclosed in braces Example PlotRange gt 0 10 PlotLabel gt plotlabel Plot type Use this control to specify the type of the plot y
191. simple example illustrates the flexibility of Mathematica Link for LabVIEW in developing distributed LabVIEW applications 112 Mathematica Link for LabVIEW Process Simulation and Control Applications Based on MathLink Mathematica Link for LabVIEW offers interesting opportunities for the development and testing of process simulation and control applications While variable and unpredictable communication intervals limit the run time practicality of MathLink to systems that respond slowly the combination of advanced Mathematica functions and LabVIEW s RAD rapid application development tools makes for a potent simulation and prototyping platform Ideally you can take advantage of the combined strengths of Mathematica and LabVIEW while designing your system Then you can use what you have learned to optimize your solution for 100 G pure Mathematica or LabVIEW RT deployment The PID Control Demo included in the Extras subdirectory of the LabVIEW user 1ib MathLink folder is a simplified demonstration of this potential The front panel for this VI is depicted in Figure 29 The basic equations used for this example were derived from Process Control Systems 4 edition by F G Shinskey All dynamic plant simulation and the PID control calculations are passed to Mathematica for evaluation In this instance LabVIEW functions primarily as an interactive GUI The LabVIEW panel tracks changes to process characteristics as well as set
192. sm 64 65 SupportedTypes 57 201 type casting 66 211 Index data visualization 14 92 93 DataTypes 202 DeclareInstrument 51 53 201 202 diagram See LabVIEW directory AddOns 26 Applications 26 dev 23 74 help 25 MathLink 23 74 Tools 25 DISPLAYENDPKT 92 DISPLAYPKT 92 distributed applications 5 9 50 55 80 110 201 Distributed MathLink applications 110 Electronic Laboratory Notebook 7 8 ELNB See Electronic Laboratory Notebook EmptyListQ vi 184 Empty MatrixQ vi 184 Error Cluster Maker vi 86 error management 15 55 84 error messages 34 ErrorClusterMaker vi 86 185 ErrorClusterMerger vi 186 ErrorOffset gbl 85 196 Extra Examples 199 extra subdirectory 24 F G Shinskey 113 FileMap 77 82 front panel 3 FTP 26 General Error Handler vi 15 86 212 Generic ListPlot vi 14 39 74 170 Generic Plot vi 14 44 47 74 172 GetBoolean vi 137 GetBooleanList vi 137 GetBooleanMatrix vi 138 GetDoubleComplex vi 138 GetDoubleComplexList vi 139 GetDoubleComplexMatrix vi 139 GetDoubleMatrix vi 140 GetInstrumentState 205 GetIntegerMatrix vi 140 GetLongDoubleMatrix vi 142 GetLongDoubleComplex vi 141 GetLongDoubleComplexList vi 141 GetLongDoubleComplexMatrix vi 142 GetLongIntegerMatrix vi 143 GetStringList vi 143 GetStringMatrix vi 144 GetVIState 205 GLP 8 GMP 8 Good Laboratory Practice See GLP Good Manufacturing Practice
193. ss creates new directories in both the Mathematica file system and in the LabVIEW file system Installed Link components interact with the MathLink libraries installed in your system directory by the Mathematica installer The Mathematica Link for LabVIEW file system is described in detail in this section The MathLink Subdirectory of the User lib Directory The majority of the Mathematica Link for LabVIEW distribution files are placed in the MathLink subdirectory of the user 1ib folder which is located inside the main LabVIEW directory The MathLink directory contains the VI libraries MLStart 11b and Tutorial 1lb and four subdirectories named dev extra LabVIEW and MLPost MLStart 11b provides a collection of standard high level VIs that can be used as limited stand alone applications or as the basis for further development These VIs are described in the section The MLStart lIlb Library on page 29 23 Use the readme vi utility to browse the content of Mathematica Link for LabVIEW 2 Installation Tutorial 11b contains the example VIs introduced in the Getting Started and Programming chapters later in this User Guide The dev directory contains five VI libraries MLComm 11b MLGets llb MLFast 11lb MLPuts 11lb and MLUtil 11b Collectively these libraries contain the VIs necessary to implement the low level MathLink functions In MLComm 11b you will find all MathLink functions dealing with communication manag
194. ssion is the way to restart the kernel Its default value is True so that a new session is automatically started when the VI is run for the first time But after completion New session is reset to False so that subsequent evaluations will be performed within the same session You can however manually or programmatically set this control to True in order to quit and restart the kernel Abort previous evaluation This control is used to abort a running evaluation Kernel Evaluation vi and any other VI sending computations to the Mathematica kernel for that matter should not be permitted to lock out the user with an infinite or very long evaluation There is a time out control implemented if the time out is exceeded then no result is returned This means that the indicator corresponding to the selected data type will not be updated and this may be easily overlooked Another way to see that no result was returned is to determine whether a new packet was added to the Packet log indicator see Logs Description on page 36 for details When such a situation occurs it is useful to be able to abort the running calculation before sending the next one Set Abort previous evaluation to True in this case An instruction to abort the computation will be sent to the kernel before the next command Make sure that there is an evaluation running before sending an abort command otherwise the kernel may qui
195. st situation is one where you have LabVIEW MLPost and the Mathematica kernel running on the same machine with no other link active Use an uninitialized shift register for each link number so as to initialize the connection when the VI is run for the first time Then use the current link numbers in subsequent evaluations Since both the link to Mathematica and the link to MLPost work in concert to render graphics you can bundle them together and use a single shift register for both of them Generic Plot vi Generic Plot viis very similar to Generic ListPlot vi It too can function as either as a stand alone application or as a subVI Some advanced settings to optimize its performance will be discussed later in this section BASIC OPERATION Generic Plot vi isa close relative of Generic ListPlot vi The main difference between the two is that GenericPlot vi does not use a list of data as an argument In order to provide the same level of flexibility as the Mathematica syntax the commands are passed as strings to this VI just as they are with Kernel Evaluation vi discussed earlier in this chapter You can use this VI to send any sequence of commands that would return graphics from the kernel The Command box is used to type in the sequence of Mathematica commands so there is no need to have a separate window for options Options can be typed directly into the appropriate place in the command string Although the name of this VI
196. standing how MathLinkCIN vi is called by VIs that implement MathLink functions None of the MathLink VIs use all the elements of the clusters of MathLinkCIN vi Rather they use only certain cluster elements depending on the kinds of data that they manipulate Look at Figure 13 to see how MLGetDouble vi calls MathLinkCIN vi You can see that the Input cluster and Output cluster are not visible on the front panel yet they are used to call the MathLinkCIN vi subVI Similarly all the MathLink VIs use the same two clusters although they are hidden from the front panel 72 Mathematica Link for LabVIEW F MLGetDouble Link in alo Link out 0 Value 0 Double error in no error error out Input and Output clusters Hidden from the front panel MathLinkCIN vi Figure 13 The MLGetDouble vi MLFunction Link out Link out out diagram and front panel Library Contents Conceptually the VIs distributed with Mathematica Link for LabVIEW can be classified into three generalized categories 1 Low level communication data transfer and utility VIs 2 Medium level VIs constructed from combinations of low level VIs and designed to automatically administer most of the Link activities transparently The medium level VIs can be used as simple stand alone applications or can be used as the basis for further development 3 Tutorial and example VIs demonstrating specific Link p
197. sult in a VI that hangs quickly It is preferable to create a buffer in the LabVIEW application where data are saved before being sent to Mathematica The recommended practice is to send the contents of this buffer in a single packet over the link when a request is detected 0 0 kal Figure 26 The MathLink Temperature vi LY 5 n Pe Pe Pe F Fpa True pp a n Analysis Structure a a 3 a a t Lo a a diagram Maximum bin je Disabled Disabled Minimum bin r Disabled Disabled Distributed LabVIEW Applications Based on MathLink In Chapter 1 the notion of using Mathematica Link for LabVIEW to distribute LabVIEW applications across several computers was introduced Admittedly several robust networking options have been introduced in recent versions of LabVIEW However if you are looking for a consistent protocol for all of your LabVIEW and MathLink applications the following example may be of interest to you 110 Figure 27 The Distributed vi front panel Mathematica Link for LabVIEW linkmode Connect Initial Time Connect Threshold 0 90 linkprotocol ppc Final Time i 0 ar i CC TCP Winner s data eee Link Name Message SY I m the Winner Connection lag Connected 75 00 4 __ In Tutorial 11b you will find Distributed vi whose front panel is shown in Figure 27 For the VI diagram see Figure 28 Use a copy of this
198. sult of MLGetSymbol vi is compared to True and the result is displayed in the boolean indicator Warning If a symbol which other than True or False is read from the link False is returned You have to make sure that True and False are the only possible symbols sent over the link before calling GetBoolean vi boolean The boolean read on the link GetBooleanList vi Link in Link out boolean list L error out error in no error GetBooleanList vi This VI reads a list of booleans from the link Since there are no MathLink functions for transferring arrays of Booleans the list is read as a function List elem 1 elem 2 elem nj In a For loop the result of MLGetSymbol vi is compared to True and the result is displayed in the boolean indicator Warnings 1 If a symbol other than True or False is read from the link False is returned You have to make sure that True and False are the only possible symbols sent over the link before calling GetBooleanList vi 2 Due to the structure of this VI its performance is limited If you need to send a large number of booleans you should probably try to send them in a numerical format and convert them in LabVIEW later TF boolean list The list of booleans read from the link 137 5 Reference Guide GetBooleanMatrix vi Link in Link out boolean matrix error out GetBooleanMatrix vi error in no error GetBooleanMatrix vi reads a mat
199. t see Troubleshooting on page 37 As an example of this feature send the following command to the kernel While True Nothing will be returned Afterwards send Names System with the Abort button turned on and with 1D Strings selected as the expected data type 33 Figure 5 Bad PrimeQ vi diagram 3 Getting Started Display error messages When this control is set to True error messages will be displayed in a dialog box with a single OK button Otherwise no dialog box is displayed which is preferable when you want to programmatically control how the error is handled Custom timing settings Built in timings should ensure smooth behavior of this VI However depending on your configuration and your computations it might be necessary to refine the timing settings When this control is set to True a pop up window appears in which three delays can be tuned Delay to quit is the time required by Mathematica to quit and is used when you start a new session It is then necessary to allow some time after closing the link before attempting to launch the kernel again Delay to launch is used when starting the kernel and Delay to evaluate is the evaluation time out Its default value is 60 seconds which should be sufficient for most applications USE AS A SUBVI Two simple examples using Kernel Evaluation vi as a subVI are included in Tutorial 1l1b They are Good PrimeQ vi and Bad Prime
200. t part of Mathematica Link for LabVIEW 4 Programming Mathematica Link for LabVIEW Mobile Robotic Experiments The examples described next were developed for a small mobile robot named Khepera see Figure 32 Khepera has sensors and actuators and can be operated via a standard computer serial port Therefore it has many features in common with instruments used in other fields and serves as an adequate model for experimentation The goal of the example applications is to specify a target trajectory for the robot and then to analyze the actual trajectory traveled from the data collected Before we get started it is important to note that the Khepera LabVIEW driver used as a subVI in the supplied examples is not included with Mathematica Link for LabVIEW Therefore you will not be able to run and interact with the examples unless you have a Khepera robot Khepera and its LabVIEW driver are commercially available from K Team S A For additional information please consult the Appendix on page 209 With the exception of the proprietary Khepera driver VIs and the robot itself all other material pertaining to the demonstrations VIs packages and documenting notebooks can be found in the Khepera subdirectory of the user 1ib MathLink Extra Advanced folder which can be found inside your main LabVIEW folder To continue with supplied exercises locate and open the Khepera pdf document in the Khepera subdirectory This concludes the f
201. tFunction vi Link in Function Argument count error in no error MLPutFunction vi Link out error out MLPutFunction vi writes a Mathematica function to Link in The function argument values will be sent after MLPutFunction The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Function The name of the Mathematica function to write to the link 162 Mathematica Link for LabVIEW MLPutIntegerArray vi Link in Link out Integer array error in no error error out MLPutintegerArray vi MLPutlntegerArray vi writes an array of integers to Link in The data are put in the Integer list The parameters used to describe the data structure are returned in the Dimensions Heads and Depth indicators The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Integer array The array of integers written to the link This cluster contains both the raw data and the parameters used to describe the data structure 116 Integer list The list of integers written to the link rma Ll 132 Dimensions The number of elements in each dimension Heads The Mathematica function name describing the data structure Example the heads of Complex a1 b1 Complex a2 b2 are List eolComplex eol
202. tedTypes Outl18 EXT DBL SGL 132 116 I8 U32 U16 U8 CXT CDB CSG EXTList DBLList SGLList 32List I16List I8List U32List U16List U8List CXTList CDBList CSGList EXTMatrix DBLMatrix SGLMatrix I32Matrix 116Matrix 8Matrix U32Matrix U16Matrix U8Matrix CXTMatrix CDBMatrix CSGMatrix Boolean BooleanList BooleanMatrix String StringList StringMatrix These are all the types of LabVIEW numbers strings and booleans plus one dimensional and two dimensional arrays of these types of data If you are not familiar with these data types each one is briefly 57 When you need to run a VI several times with CallByReference use OpenVIRef first 3 Getting Started documented on line Information for each data type can also be obtained using the Mathematica query operator Here is an example In 19 CXT LabVIEW data type complex extended precision floating point number You can also refer to the LabVIEW documentation for more details Now connect to the VI server once again Go into LabVIEW run MathLink VI Server vi then go back to Mathematica to get connected and to call the instrument Type the following commands In 20 link ConnectToServer Out 20 LinkObject 5555 3 2 In 21 CallByReference link inst or alternatively using the victl 11b terminology CallInstrument link inst Frequency Response vi successfully operated Out 21 1000 Before the result
203. that the array fits the data structure when using this VI Inconsistent incoming data read by this VI can lead to a MLEGSEQ MathLink error long double complex The complex number read from the link GetLongDoubleComplexList vi Link in Link out long double complex list a error out GetLongDoubleComplexList vi error in no error GetLongDoubleComplexList vi reads a list of complex numbers from the link This VI is based on MLGetLongDoubleArray vi Warning Since there is no MathLink function to verify that the incoming array fits a list of complex numbers data structure it is your responsibility to ensure that the array fits the data structure when using this VI Inconsistent incoming data read by this VI can lead to a MLEGSEQ MathLink error txT long double complex list The list of complex numbers read from the link 141 5 Reference Guide GetLongDoubleComplexMatrix vi Link in Link out EEA long double complex matrix error in no error T P error out GetLongDoubleComplexMatrix vi GetLongDoubleComplexMatrix vi reads a matrix of complex numbers from the link This VI is based on MLGetLongDoubleArray vi Warning Since there is no MathLink function to verify that the incoming array fits a matrix of complex numbers data structure it is your responsibility to ensure that the array fits the data structure when using this VI Inconsistent incoming data read by this VI can lead to a MLEGSEQ MathLink err
204. that you expect as the result of the computation The result of the computation is sent to the appropriate element of one of the three clusters positioned on the right side of the front panel In Figure 4 only the Basic data cluster is displayed Two other clusters 1D Arrays and 2D Arrays which are used to collect lists and matrices of data are not visible in the operational mode depicted in the figure 31 3 Getting Started Figure 4 The Kernel Kernel evaluation Evaluation vi Command front panel integer Expected type F Integer New session True Basic data Abort previous evaluation O False Boolean Display error messages True Custom timing settings O False as _ Parga py j neos Link out fo po Real error out 0 0000E 0 Complex 0 0000 0 0000 i String jd Use of Kernel Evaluation vi This VI can be used either as a main application or as a subVI in larger applications Some advanced settings to optimize its performance are discussed later BASIC OPERATION The default values of the controls are set so that you can run the VI immediately If you worked through the hands on exercises introduced at the beginning of this chapter you have already used this VI to compute the result of 2 2 If you skipped over the tutorial exercises type 2 2 into the Command box and run this VI now to verify your installation of Mathematica Link for LabVIEW
205. the same time For instance if you want to control a VI from within a Mathematica notebook you may need to switch back and forth frequently between the Mathematica front end and LabVIEW In this situation setting the cooperation level to high may improve the response of your application significantly When the cooperation level is set to low switching from LabVIEW to another application occurs much more slowly Thus setting the cooperation to a high level may be advisable even though it can impact the execution speed of your LabVIEWapplication 27 3 Getting Started Figure 2 Accesssing MathLink items in the LabVIEW Tools menu Immediate Gratification If you are interested in immediate hands on interaction with Mathematica Link for LabVIEW there are a couple of options available to you If you would first like to see the Mathematica kernel operating as a sub process of LabVIEW experiment with the Mathematica Shape Explorer viorthe PID Control Demo Both of the demos can be accessed via the MathLink gt Extras menu of the LabVIEW Tools menu see Figure 2 if Finding Items in the Tools menu wi File Edit Operate MEMES Browse Window Help lI Instrumentation Compare Y Revision Histor Ctr User Name Edit 1 Library MathLink Advanced p Web Publishing Tool a Display BMP Main a Generate_Graphic_File Advanced Release otes MLShapeExplorer p O
206. thematica Link for LabVIEW PutBooleanList vi Link in TE Link out boolean list iH error in no error x error out PutBooleanList vi PutBooleanList vi writes a list of booleans over a link Warning Since there is no MathLink function for transferring arrays of booleans the list is passed as List elem 1 elem 2 Consequently the performance of this VI is limited If you need to send large lists of booleans you should try to code them in a numerical format and convert them in Mathematica afterwards boolean list The list of boolean values that will be sent over the link PutBooleanMatrix vi Link in Link out boolean matrix error in no error u error out PutBooleanMatrix vi PutBooleanMatrix writes a matrix of booleans over the link Since there is no MathLink function for transferring arrays of booleans the matrix is read as a compound Mathematica expression List List elem 1 elem 2 elem n In two nested For loops True or False is sent by the MLPutSymbol function according to the value of the current matrix element Warning Due to the structure of this VI its performances is limited If you need to send large numbers of booleans you should probably try to send them in a numerical format and convert them in Mathematica afterwards TF boolean matrix The matrix of booleans to write over the link 145 5 Reference Guide PutDoubleComplex vi Link in Link out double ee error in no erro
207. tica graphics presentation within a LabVIEW application There are two important areas where Mathematica can complement LabVIEW s built in data visualization tools These are functions that plot analytical functions which we refer to as Plot functions and functions to visualize lists of data which we refer to as ListPlot functions The VI that calls all Plot functions is named Generic Plot vi and the one that calls all ListPlot functions is named Generic ListPlot vi Rendering graphics in Mathematica is somewhat more complicated than evaluating a command that returns data since it is necessary to use an ancillary application named MLPost Mathematica graphics are PostScript graphics which must be interpreted by a PostScript interpreter application in order to be rendered on a computer monitor In the usual Mathematica configuration i e the notebook front end interacting with the kernel the kernel returns the PostScript code to 38 Mathematica Link for LabVIEW the front end before it is displayed in the notebook Since neither LabVIEW nor the kernel can interpret PostScript code it is necessary to call an external PostScript interpreter to generate a bitmap version of the graphic that can be displayed in a LabVIEW window MLPost is the PostScript interpreter that performs this task It is operated through a MathLink connection directly managed from within LabVIEW The VIs of MLStart 11b take care of these issues for you
208. tor character will be stripped off the path Second the control list is verified Its structure is compared to the general control pattern and the control value and control type are verified to be consistent The same kind of verification is conducted on indicators except that indicators do not have values to verify DeclareInstrument is fairly flexible If for any reason you do not need to declare controls or indicators use one of the following forms 202 Mathematica Link for LabVIEW e DeclareInstrument path e DeclareInstrument path indicators e DeclareInstrument path controls e DeclareInstrument path controls indicators Since controls and indicators do not have the same pattern this definition set is not ambiguous Instrument Editing Functions When an instrument has a large number of controls using DeclareInstrument to change a control value or to add another indicator to the indicator list can be tedious Instrument editing functions are provided to help you with this task SetControls instrument controlname controlvalue can be used to change a control value in a declared instrument You cannot change the control type SetControls instrument controlname controlvalue can be used to change the values of several controls in a declared instrument You cannot change the control types AddControls instrument name type value can be used to add a new control to the control list of a declared
209. tribute node 179 5 Reference Guide Indicator2bin vi Link in Link out Output types a Desired output error out error in no error Indicator2bin vi Indicator2bin vi is used to flatten incoming indicator descriptions to pass them to Call Instrument vi This VI is a subVI of MathLink VI Server vi 116 Output types The series of positions in supported types of data read from the link San Desired output An array of clusters containing a control name a type descriptor and flattened data You can get the type descriptor and the flattened data from the Flatten to String function This cluster is wired to the Desired output cluster Kernel Initialization vi Initialization package Kernel Initialization vi Kernel Initialization vi is only used to send the initialization package to the Mathematica kernel when it is launched by Kernel Evaluation vi Generic ListPlot vi and Generic Plot vi Initialization package This package is used to initialize the kernel when it is launched by Kernel Evaluation vi Generic ListPlot vi and Generic Plot vi of Mathematica Link for LabVIEW It contains a single function EvaluateUserlnput which ensures a compatibility between Mathematica data types and LabVIEW 180 Mathematica Link for LabVIEW Launch Kernel vi Timeout 60 s Link out Mathematica path error in no error ki Launch Kernel vi Launch Kernel vi opens a link in launch mode to the Mathematica kernel
210. trol must be described by its name data type and value The indicators that you want to read are specified in the second list Naturally you do not have to provide indicator values these will be returned at run time however you must provide the name and type for each indicator of interest Here is an extension of the example used in the previous section In 17 inst DeclareInstrument HD LabVIEW examples apps freqresp llb Frequency Response vi Amplitude DBL 1 5 Number nof Steps 132 20 Current Frequency DBL Out 17 5 6 Important note control and indicator names must be entered as they appear on the VI diagram Mathematica Link for LabVIEW Instrument HD Lab VIEW examples apps freqresp IIb Frequency Response vi Frequency Response vi Amplitude DBL 1 5 Number of Steps 132 20 Current Frequency DBL Read this output carefully The second control is named Number nof Steps Why is it necessary to place the n between Number and of The answer lies in the VI diagram Whereas the control label is written on a single line on the front panel it is written on two lines in the diagram If you do not introduce the n the Mathematica newline character in the control name Call Instrument vi will not recognize it You can easily query Mathematica to access the list of data types supported by the DeclareInstrument function In 18 Suppor
211. turn a LinkObject that you can save in a variable so that all VI operating functions can use it If for some reason the default settings do not work with your configuration you can use different options or even a different link name to get connected ConnectToServer has the same options as LinkOpen Refer to LinkOpen documentation and to Getting Connected on page 75 for more details on this topic Shutdown The ServerShutdown function is provided to close the link to the server This function sends a message to a running VI server When received the message is acknowledged and the server will close the link and stop When the acknowledgment is received by Mathematica it closes its side of the link A VI server should not be stopped from the LabVIEW side since the LabVIEW operator theoretically has no means of knowing whether or not the connection is going to be used It is the client s responsibility to release the link Basic VI Operations Background Mathematica Link for LabVIEW was originally developed before the introduction of LabVIEW s VI Server that powerful VI control technology that permits advanced control of all aspects of VI operations Before VI Server the vict1 11b offered a small collection of control functions features that are now integrated into the VI Server Previous versions of Mathematica Link for LabVIEW relied exclusively on the vict 11b functions to dynamically call VIs from a 204 Mathemati
212. unications mechanism for your distributed applications 10 Stand Alone Mathematica Applications Because Mathematica s text based interface is so flexible users unfamiliar with the syntax of the language may experience difficulties when attempting to run applications in the standard Mathematica front end By embedding kernel evaluations into the LabVIEW framework you can build robust stand alone GUI applications that anyone can run For example the neural net used to run a Khepera robot is easily computed in Mathematica However setting up the connection weight matrix can be difficult due the abstract nature and large size of the matrix An attractive and convenient design is to build a VI where the connection between neurons is graphically represented on the front panel The VI controls are used to set the weights of the neural net connections At run time all the computation parameters connection weights and current state of the network are passed to the Mathematica kernel to compute the new state of the network For more information and an actual example involving a Khepera robot refer to Khepera pdf This document and other support files are installed in the LabVIEW user lib MathLink extra Advanced Khepera directory 1 Introduction What is Mathematica Link for LabVIEW 10 A Powerful Synergistic Workflow Mathematica Link for LabVIEW allows you to interact with your instruments in an entirely new way Using a combinatio
213. usly mentioned there are few commercial software packages that can be used as electronic laboratory notebooks The functionality of the new digital tools is still being evaluated Prototypes that can be tested under real laboratory conditions will be required to prove the concept Currently Mathematica Link for LabVIEW does not have the full functionality of an electronic laboratory notebook Nonetheless it may be considered a first step in that direction The package provides the user with the ideal unified working environment instruments and Mathematica Link for LabVIEW experiments can be controlled and results can be reported automatically 9 Quickly build distributed LabVIEW applications MathLink provides functions to exchange complex data in a homogeneous way independent of the computers used and the underlying transfer protocol Although LabVIEW provides other native communication options TCP VIs DataSockets VI Server and so forth the MathLink libraries may also be used to distribute an application among several computers Such applications can be written in a platform independent way The advantage is that you do not have to master intricate protocols such as TCP or PPC to be able to write a distributed application MathLink functions take care of the details for you Once you are comfortable with MathLink programming techniques you will have the option of using the same high level functions to provide the comm
214. ut MLPutDoubleArray vi MLPutDoubleArray vi writes an array of doubles to Link in The data are returned in the Double list The parameters used to describe the data structure are returned in the Dimensions Heads and Depth indicators The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Double array The array of doubles written to the link This cluster contains both the raw data and the parameters used to describe the data structure DEL Double list The list of doubles written to the link 137 Dimensions The number of elements in each dimension re jr Leaf J Heads The Mathematica function name describing the data structure Example the heads of Complex a1 b1 Complex a2 b2 are List eolComplex eol Depth The array depth Example 2 for a 3 x 3 matrix 161 5 Reference Guide MLPutDoubleList vi Link in Link out Double list error in no error error out MLPutDoubleList vi MLPutDoubleList vi writes a list of real numbers to Link in The Value indicator returns a nonzero value if the operation was successful or zero if an error occurred In this case the error can be identified with MLError Warning In LabVIEW it is not necessary to specify the list length as a separate argument of this function bEL Double list The list of doubles to write to the link MLPu
215. ut long double ae list error in no error error out et PutLongDoubleComplex vi sends a list of complex numbers over the link t T long double complex list The list of complex numbers sent over the link PutLongDoubleComplexMatrix vi Link in Link out long double nae matrix error in no error error out Siting Double Compresa al PutLongDoubleComplex vi sends a matrix of complex numbers over a link long double complex matrix The matrix of complex numbers sent over the link 147 5 Reference Guide PutLongDoubleMatrix vi Link in Link out long double matrix error in no error n error out PutLongDoubleMatrix vi PutLongDoubleMatrix vi sends a matrix of long doubles over a link long double matrix The matrix of long doubles sent over the link PutLongIntegerMatrix vi Link in Link out long integer matrix error in no error n error out PutLongintegerMatrix vi PutLongIntegerMatrix vi sends a matrix of long integers over the link long integer matrix The matrix of long integers sent over the link PutStringList vi Link in Link out string list D N error in no error error out PutStringList vi PutStringList vi sends a list of strings over the link Warning Since there is no MathLink function for transferring an array of strings the list is written as a function List elem1 elem2 MLPutString is called sequentially in a For loop Due to this structure the performance of this VI is lim
216. where MathLink functions are called To some extent this VI can be viewed as a Mathematica LabVIEW translator Mathematica can maintain a dialog with the C program through MathLink This C program can also carry on a dialog with LabVIEW 62 Mathematica Link for LabVIEW through a Code Interface Node Thus Mathematica and LabVIEW can exchange information through MathLink and a Code Interface Node Figure 11 The global structure of Mathematica Link for LabVIEW a N MathLink VIS LabVIEW hierarchical design Code Interface Node A second link is used to send Evaluation parameters and PostScript graphics to MLPost evaluation results are transmitted and to read the bitmap AN over the link to the kernel version of the picture MLPost OoN Mathematica kernel The global structure of Mathematica Link for LabVIEW is illustrated in Figure 11 A LabVIEW application can use MathLink functions by using VIs that implement those MathLink functions These VIs themselves call the CIN containing VI MathLinkCIN vi The external C code is where the actual MathLink functions are called Three Sets of Data Types In order to avoid confusion you must keep in mind that when you use Mathematica Link for LabVIEW three programming languages are working together each having its own set of data types Mathematica data are mainly expressed as compound expressions composed of atoms belonging to a limited set of atomic data types The types
217. wser Manual installation of the Mathematica components is now complete LabVIEW Settings The following LabVIEW settings can have a significant influence on the performance of Mathematica Link for LabVIEW These settings can be found in the Performance amp Disk section of the Options dialog box consult the LabVIEW documentation for more details Memory Deallocate memory as soon as possible You may want to consider using this option when generating high resolution graphics particularly when system memory resources are limited Activate this option if a first attempt to generate a graphic results in a warning message 26 Mathematica Link for LabVIEW stating that the available memory is low and more memory cannot be allocated to LabVIEW Compact memory during execution Macintosh only This option can also help in coping with memory shortage problems especially with graphics intensive applications Cooperation Level Macintosh Only In most typical Mathematica Link for LabVIEW configurations the Mathematica kernel and your LabVIEW application will share the same CPU If performance is an issue it can be critically important to adjust the time yielded by each application to the other If you need good performance on the LabVIEW side and only require short evaluation periods for the Mathematica kernel you should set the cooperation level to low In some cases you may need to interact with the two applications at
218. xamples As indicated earlier in this chapter several simple examples have been provided to illustrate applied uses for MathLink functions in LabVIEW applications All of these examples are contained either in Tutorial 11b or the Extras subdirectory of LabVIEW user lib MathLink folder However you may find it more convenient to access these examples through the LabVIEW Tools menu Basic Front End vi Basic Front End vi shown in Figure 20 and Figure 21 is an interesting programming example mainly because it illustrates an alternative method to program a MathLink application As detailed in the section Packet Parser vi on page 89 custom applications are required to process Mathematica expressions returned by the kernel One way to side step this requirement is to return all evaluation results from the kernel in the form of strings The advantage of this approach is that a systematic treatment of command results can be implemented However the drawback is the information returned by the kernel cannot be used directly in subsequent computations since the data types are lost in the MathLink transaction As you can see in Figure 20 Basic Front End vi offers a text interface to the kernel similar to the kernel window This VI can be used to control the kernel as a rudimentary front end When you run the VI you are prompted to locate the Mathematica kernel that you want to launch In the Command Line box you can type any Mathematica

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