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1MA228_e_LabVIEW_Drivers

1. ACG ii ai Name search Version 4 2 0 Search in Attributes RSSPECAN_ATTR_SWEEP_MODE_CONTINUOUS 331 Search in Functions tay Configuration Configure Acquisition vi CE RSSPECAN_ ATTR NUMBER_OF_SWEEPS O Monitor Clipboard o SENS SWE COUN Search for the name co SENSe SWEep COUNt Konfigure Acquisition vi o INIT CONT INITiate CONTinuous ON OFF Fig 4 3 SCPI command searcher invoked with selected driver Hi level function e Clipboard monitoring is a useful when you browse the device user manual copy ing the SCPI command will immediately trigger the search and displays the result Also browsing the driver help file and copying the function attribute name will help you to immediately drag it to your Block Diagram instead of searching the palette or your disk folders See the short video attached to this application note showing how you can quickly compose your program in combination with an instru ment user manual 4 2 Connect and Align plugin Default keyboard shortcut CTRL A After CTRL SPACE This plugin will speed up the tedious tasks of connecting your driver VI nodes and terminals together with VISA and error cluster wires It takes the X coordinates of the selected objects on your Block Quick Drop Plugins Diagram and aligns them into a chain by moving them and making horizontal space Here are the main features that of this plugin e The order of connection is only defined by the X c
2. m a Sst PI ho fe in oi j Erronevent Output queue buffer ESE Fig 7 2 Instrument status reporting system showing ESR ESE and STB registers Sending OPc at the end of the command makes the instrument generating the Opera tion Complete event in ESR after all pending commands have been processed The occurrence of this event can be then read from STB register bit 5 ESB The reason for reading the STB register instead of direct reading of the ESR register bit 0 is that VISA provides viReadSTB function which doesn t query the instrument at all as opposed to ESR or STB queries but only reads the session internal STB register on the con troller PC The STB content synchronization between the controller and the instru ment is handled by the instrument session automatically and therefore it optimizes the traffic and the speed on the controller instrument interface The advantage compared to OPC synchronization method is that your application can perform other operations while waiting for the instrument to report the operation complete This method of synchronization is used internally by the driver in function Wait For OPC vi As shown in the example you need to use the timeout different from VISA timeout to prevent a dead lock The Express VI doesn t provide this syn chronization option Application Note Instrument Drivers LabVIEW 1MA228 4e 46 7 3 1 3 1 7 3 2 7 3 3 Tips when using drivers Tips when us
3. E amr Application Note Instrument Drivers LabVIEW 1MA228 4e 13 4 Quick Drop Plugins Quick Drop plugins are available for all the drivers released in 2015 and later The older drivers will be gradually updated to be able to use these plugins Quick Drop plugins SCPI command searcher and Connect and Align are part of rsidr_toolbox library shared by all drivers The rsidr_toolbox also contains Express VI configuration panel To achieve the best performance all the Block Diagrams are removed during the deployment Installation Download and run the rsidrToolboxInstall vi that is available as an attachment to this application note http www rohde schwarz com appnote 1MA228 The VI will deploy or update the content of user lib rsidr toolbox folder and copy the Quick Drop Plugins SCPI command searcher RS_Drivers vi and Connect and Align RS_toolbox vi to the Quick Drop plugins folder resource dialog QuickDrop plugins Usage On the Block Diagram activate the Quick Drop with the CTRL SPACE short cut the first activation is slower because the Quick Drop window populates the list of all functions and palettes Then use the plugin specific keyboard shortcut see the description if the following chapters A different shortcut can be set in the Quick Drop Shortcuts settings dam Quick Drop Shortcuts Front Panel Block Diagram Ctri Key Shortcuts NET Object To Variantvi F default RS_drivers vi 1D ANOVA NI_AALPro
4. 2 1 Example of non attribute based FSEx driver function VI About LabVIEW drivers 2 1 2 DLL wrapper around the VXI plug amp play driver This type of driver uses the VXI plug amp play d11 library Although there are some advan tages to this approach common source code for all types of drivers faster execution speed smaller load on memory and disk space the main disadvantage is that it s not a LabVIEW code and the user cannot see it or alter it Therefore this type is now only used for older instruments and for the ones that use proprietary communication proto cols without VISA support e g USB NRP Z power sensors The dll wrapper drivers are easily recognizable by msi installation package since they always require installa tion of VXI plug amp play driver Installation The driver installation is a msi package that installs VXI plug amp play driver and LabVIEW VIs to c Program Files x86 IVI Foundation VISA GWinNT lt driver name gt To have the access to the driver palette copy the folder lt driver name gt to c Program Files x86 National Instruments LabVIEW 2010 instr 1ib folder and restart LabVIEW 4 RSUPV Initialize vi Block Diagram File Edit View Project Operate Tools Window Help RSUFY jan ot 15pt Application Font ee tal No Error Ma EEEE EG EEDE EEE LE EGE GE gE error in no error F rsupw_init in rsupy_64 DLL Resource Name GPIB 20 SHEP co error out ID
5. LabVIEW drivers 2 1 2 1 1 LabVIEW driver types Over the time Rohde amp Schwarz LabVIEW driver technologies have gone through sev eral phases of improvement due to internal and external factors more instrument capabilities and higher complexity driver specification changes Currently Rohde amp Schwarz LabVIEW drivers can be split into three groups in order from older to newer Non attribute based driver This type has direct VISA Write vi and VISA Read vi inside the function VI This approach is not used anymore because they are difficult to maintain they don t per form error checking and if used with modern spectrum analyzers or signal generators the driver would contain thousands of VIs e g rsrfsiggen driver has over 4000 attrib utes which would result in over 8000 VIs read write Installation Copy the instr 1ib folder to c Program Files x86 National Instruments LabVIEW 2010 In the drivers released before 2015 the folder user 1ib is either not present in the installation package or it is empty In the later ones it contains a Crosslinks bin file for Quick Drop SCPI command searcher Refer to chapter 4 1 SCPI command searcher plugin on page 15 for more details 4 RSFSEx Start and Stop Freg vi Block Diagram File Edit View Project Operate Tool Window Help Start Freq 20 0 Hz DeL Stop Freq 3 5e9 Hz DEL VISA session Lot nase b dup VISA session error in no error LSsck error out Fig
6. Spectrum Analyzer lib Configure Frequency Center Span vi Block Diagram File Edit View Project Operate Took Window Help ara Set Frequency Span 4 FIFO VISA resource name out error out Fig 2 3 Example of attribute based rsspecan driver Hi level function VI for setting center frequency and span using two Express VI instances After restarting LabVIEW the driver functions are accessible through palette menu LabVIEW driver types Functions Instrument VO DRIVERS I z Instr Drivers m 4 Instrument Drivers Rohde amp tSchwarz Snectrum Analwzer F Rohde amp Sch Rohde Sch Programming ey Reut ite CONFIG A ey stbu G poe Measurement a E Cii Vision ami kint rsspecan rszvb VI Tree wi Initialize vi Close vi Configuration MEAS Plulti Mathematics a i Stand r o tandar A F Radic I a Mi mn Signal Processing Measurement IQ Analyzer Multi Standa Data Manag Data Communication UTILITY F F F Te EE Input Connectivity g io TYGR me Ub Control Design amp Simulation k Utility Realtime Spe External Mixe Baseband Po SignalExpress j FENER l PULSE AHALOG EM eo ali Denon ete Express Addons Favorites User Libraries j Select a VI 2p A GEM GSM Measur Multi Carrier a F HOISE amp FHASE p EMI Figure Phase Noise EMI Measure Ie vos F F To a 3G
7. Use transparent free labels 7 Use transparent name labels Labels locked by default Default label position Default E Show subVI names when dropped Wiring Enable automatic wire routing Enable auto wiring Fig 5 3 Configure Express VIs immediately settings LabVIEW places the Express VI instance on your Block Diagram in full view Fig 5 4 Express VI instance in full view You can explore available terminals by dragging red marked arrow 5 3 Express VI Configuration panel rsspecan_core_a ttribute_express Source vl t Attribute ID Instrument harnck pe ee ea Fig 5 5 Express VI instance with expanded terminals Right click context menu item View As Icon switches to standard Icon view After placing reconfiguring the Express VI instance you can simply make copies of it in your Block Diagram by CTRL C V or CTRL Dragging making a copy or CTRL SHIFT Dragging making a copy with vertical or horizontal alignment The Express VI instance configuration is copied as well Configuration panel also generates quick help content You can view it in Context Help window shortcut CTRL H As an exam ple see figure 5 13 Express VI Configuration panel Double clicking on an Express VI instance or selecting Context menu gt Properties brings up the Configuration panel See how to speed up the loading of the Express VI Configuration panel here chapter 7 3 3 Mass compile your driver before th
8. gt attr chm rsspecan_attr chm Microsoft CHM file that shows the attribute tree structure which is used by the Express VI Tree control to access the desired attribute Initialize vi Driver structure 4 VISA resource name out 15 error out error in mo error 11 This is a basic VI that opens a session to the instrument based on the input VISA resource name Output VISA session is then used throughout the driver as a han dle for communication with that specific instrument VISA session is compatible with all VISA palette Vis including VISA Read vi and VISA Write vi Important Don t use VISA Open vi from LabVIEW palette to initialize a ses sion because Initialize vi also creates additional data for the session that are needed later on Optional parameters are Reset defines whether to send RST to the instrument after initialization and ID Query checks based on the instrument response to IDN query whether it is among the listed supported devices for this driver In special occasions you might want to disable ID Query if you are sure that the driver can handle your instrument Disable Reset if your instrument already has a setting that you don t want to lose Close vl VISA resource name 11 ket error in no error 8 0 error out This VI closes the instrument session and frees all additional session data Important Don t use VISA Close vi from LabVIEW palette to close a ses sion because Close
9. no error in error out cluster Note LabVIEW doesn t put Vis whose names Start with underscore to palettes There fore you will not find check error vi in Utilities LabVIEW palette You have to use your file explorer or Quick Drop CTRL Space to access it EA Application Note Instrument Drivers LabVIEW 1MA228 4e 12 Getting started with using attribute based drivers 3 1 1 6 Get Timeout vi Set Timeout vi These Vis get set session based parameter OPCtimeout waiting for the operation to be completed e g measurement sweep The driver synchronizes with the instrument by sending OPC not OPC at the end of the command and then periodically polling the Status register bit 6 OPC Important Because of this synchronization mechanism the VISA Timeout parameter has no effect on the driver s measurement timeout You need to change this custom session based parameter to prevent long measurement timeout errors 3 1 1 7 Revision Query vi This VI returns the driver version and instrument firmware version 3 1 1 8 Reset vi This VI sends RST to the instrument waits for the reset to be completed and applies a default instrument setup same as during the initialization 3 1 1 9 Instrument IO folder This folder contains VIs for direct SCPI queries and Vs for transferring files between the PC and the instrument Direct SCPI command writing can be performed with VISA Write vi from the LabVIEW VISA palette
10. user to do the comparisons on his setup using attached programs and scripts E Application Note Instrument Drivers LabVIEW 1MA228 4e 42 Building Executables 7 Tips and Tricks 7 1 Building Executables All Rohde amp Schwarz attribute based drivers use standard functions for writing reading the following attribute data types 132 Double String Boolean Enum treated inter nally as 132 In case that attribute parameter cannot be formatted using these stand ard types the drivers use functions called Callbacks Usually a pair of Callbacks is defined for both writing and reading operations All of these callbacks are stored in the driver structure Private callbacks folder When running in development environ ment the driver dynamically calls the Callback if an attribute requires it But if you cre ate an executable with your Top level VI none of the Callbacks are in its dependency list therefore they will not be included into your executable application As a conse quence if you run your executable the first use of attribute requiring a Callback will report the error 1074003958 OxBFFCOOOA with following text Cannot find dynamically called callback lt callback name gt Make sure that all VIs are in correct folders If deploying folder structure has to be maintained To solve this error go to your Project Explorer window Build Specifications and open your desired application in our case MyApplication Properties
11. vi also clears all additional session data that the Initialize vi has created Utility folder don t mix with utility is outlined in the next chapter Driver structure 3 1 1 Utility folder functions 4 Rohde amp Schwarz Spectrum Analyzer Utility fal Ieee VI Treevi rsspecan_cor Initialize wi Close vi COHFIG F i a Multi r tandar 38 ain e nalysiz Configuration Measurement JQ Analyzer Multi Standa 5 FAIL RESULT Reset vi Configure Er Self Testvi Self Test Res ie Eluctooth i EEN FM Stereo Bluetooth A Revision Que System Versi Applications Error Query vi Fig 3 1 rsspecan LabVIEW Utility palette This folder contains VIs that change the driver s behavior error handling VIs instru ment reset and self test Vis etc The following chapters will describe the ones most commonly used 3 1 1 1 Error Message vi ce ERR M0 This VI is a wrapper over the generic LabVIEW General Error Handler vi that also translates the driver error codes to human readable form Use this VI instead of the General Error Handler vi to confortably handle the driver errors 3 1 1 2 Instrument Status Checking vi gt TCheck This VI changes the session based parameter ErrorChecking which is set to ON dur ing initialization When ON the driver calls the VI check error vi see below that Getting started with using attribute based drivers 3 1 1 3 3 1 1 4 3 1 1 9 se
12. window 7 2 Synchronization methods 4 Project Explorer MyApplication vproj File Edit View Project Operate Tools Window Help laSa x OOX SP aR A al Rwe b Project MyApplication lvproj S My Computer H MyApplication vi H Rohde amp Schwarz Spectrum Analyzer lvlib E Y Dependencies we Build Specifications Source Files be My Computer _ File Settings i MyApplication vi con E A Rohde amp Schwarz Spectrum Analyzer Additional Exclusions Version Information packs Windows Security lel Check Before Read vi Shared Variable Deployment ful Check Option vi Pre Post Build Actions _Clear Before Read vi Preview faa _Coercing Warning vi all Default Instrument Setup vi full Get Trace Data vi ie _Get Trace IQ Data vi a Parse Catalog List vi Read Long Data vi NRT Wait For OPC vi ff Attribute ctl fag Read Trace Data Byte vi fal Read Trace Data Integer vi fa Read Trace Data vi fa rsidr_core_add_rep_cap vi fall rsidr_core_attribute_cache_rea fad rsidr_core_attribute_cache_wri _ all rsidr_core_attribute_read_bool fall rsidr_core_attribute_read_int v fail rsidr core attribute read real r Fig 7 1 Building an executable requires adding entire callbacks folder to Always Included set of VIs or folders Select Source Files in Project Files open Rohde amp Schwarz Spectrum Analyzer lvlib element and navigate to Private callbacks folder Add the entire folde
13. 14 39 File folder Public 09 01 2015 15 00 File folder _ Rohde amp Schwarz Spectrum Analyzer aliases 07 01 2015 11 29 ALIASES File Rohde amp Schwarz Spectrum Analyzer html 25 11 2014 16 39 Firefox HTML Doc a iguanas 3 Rohde amp Schwarz Spectrum Analyzer lvlib 09 01 2015 15 00 LabVIEW Library Log Results 10 _ Rohde amp Schwarz Spectrum Analyzer lvips 25 11 2014 16 39 LVLPS File Reload CINs E Rohde amp Schwarz Spectrum Analyzer lvproj 07 01 2015 10 44 LabVIEW Project Include warnings for read only VIs A A Mass Compile Computer Fig 7 3 LabVIEW Mass Compilation of the driver instr lib folder LabVIEW will compile all Vis in the selected folder and all sub folders to the actual ver sion It also compiles all Vis in 11b libraries All the new drivers released later than 12 2014 have the automatic mass compilation of the user lib folder If your driver is of older date repeat the same procedure for the folder user 1lib express rsspecan This is especially significant for Express VI Configuration panels because LabVIEW will never do it automatically and that leads to a silent compilation of this code every time you configure you Express VIs Use Express VI variable RepCaps settings Instead of composing Express VI Repeated Capabilities input string yourself use the Variable RepCaps setting in the Express VI configuration window The variable Rep Caps work up to 6 RepCaps The posi
14. 7 e 9 Post operation Depending on selected Attribute operation WAI OPC synchronization and Error Checking are available Refer to chapter 5 3 1 8 Attribute operation control on page 27 For details on different synchronization methods refer to chapter 7 2 Synchronization methods on page 44 e 10 RepCaps string control This string contains values for repeated capabilities defined in SCPI command by information in curly brackets Repeated capabilities are case sensitive separated by comma if there are more than one no spaces are allowed Actual values depend on attribute definition and can be found in attrib ute help under Supported Repeated Capabilities If the selected attribute has 1 or more Repeated capabilities defined this control is enabled for editing Invalid repeated capabilities string will be marked with red label and will disable OK button 14 Repeated capabilities string is allowed to be empty for standard Read Write operation if no variable RepCaps are selected for all others it must be valid Edit ing options besides free writing Right click context menu Fill with 1st options will set the first valid Repeated capabilities string Double click on empty RepCaps string control will do the same as Fill with 1st options or in case the attribute has no definition for Repeated capabilities RepCaps string control will be cleared Double click on valid repeated capability or using Right click conte
15. 89 4129 0 Fax 49 89 4129 13777 www rohde schwarz com This application note and the supplied programs may only be used subject to the conditions of use set forth in the download area of the Rohde amp Schwarz website R amp S is a registered trademark of Rohde amp Schwarz GmbH amp Co KG Trade names are trademarks of the owners
16. EC OFF LabVIEW driver Express Vis Standard operations 0 04 0 03 EC OFF LabVIEW driver Express VIs Fast oper ations LabVIEW raw VISA write read Visual Studio 2012 C Spyder Python with PyVISA Below the last column Measurement time in seconds by speed from the slowest to the fastest Measurement time in seconds LabVIEW driver Express Vis Standard operations LabVIEW driver Standard configuration Spyder Python with PyVISA Express Vis E Error Checking ON additional time E Error Checking OFF Fig 6 1 VXI 11 duration time results of the Measurement task LabVIEW driver 64 07 45 22 EC OFF 49 73 30 21 EC OFF represented in graph sorted Visual Studio 2012 C LabVIEW raw VISA write read Fast operations Results using HiSLIP protocol 6 2 Results using HISLIP protocol Table 6 2 Result table for HiSLIP protocol EC OFF means that Error Checking was switched OFF IDN loop time in sec Configuration time in Measurement time in onds seconds seconds N A LabVIEW driver Stand 0 07 41 27 ard configuration 0 06 EC OFF 31 65 EC OFF LabVIEW driver N A 0 03 31 47 Express Vis Standard 0 03 EC OFF 21 44 EC OFF operations LabVIEW driver N A Express Vis Fast oper ations LabVIEW raw VISA 2 03 write read Visual Studio 2012 C 2 03 Spyder Python with 2 48 PyVISA Below the last column Measurement time in seconds represented in graph sorte
17. EW 1MA228 4e 33 Express VI Configuration panel En Fig 5 12 Example of an Embedded Express VI instance Open the context help CTRL H and hover the mouse over the Express VI to see its configuration and short help for the selected attribute 9 3 2 6 9 3 2 7 Express VI Configuration panel Locked Context Help Set Trace Type TR4 ATTR_TRACE_TYPE DISP WIND TRAC4 MODE senum 4833 RepCap Trace TRA 1 instrument handle 0 4 instrument handle out Trace Type 5 Maxhold MA 9 2 15 error out error in mo error 11 This Express VI is configured as follows Attribute Operation Standard Write Attribute ID RSSPECAN_ATTR_TRACE_TYPE Associated Hi level functions 2 Configure Trace wi Trace Phase Settings vi Repeated Capabilities default TRA variable RepCap Trace TRA Input value 32 represented as Ring control 3 Maxhold MAH SCPI command DISP WIND TRAC4 MODE MAXH This attribute defines the type of display and the evaluation of the traces in the selected measurement window WRITE corresponds to the Clr Write mode of manual operation The trace is switched off BLANK in manual operation with DISP WIND TRAC STAT OFF The number of measurements for AVERage MAXHold and MINHold ts defined with the command SENSe AVERage COUN or SENSe SWEep COUNE It should be noted that synchronization to the end of the indicated number of measurements is only possible in single
18. FF ileal al au Analvrir et eel a WEDHA E Transient An VSA WCDMA F D TD SCDMA og m a E z a 5 COMHA p COMA p COHA p COMA cong EST MST E po k a ry EST CDMA2000 COMAZ2000 B CDMA2000 1 1xEV DO Bas Eoma F 02 11 F Wiha F LTE a HET j yi vi Ee 1xEV DO Mo IEEE 802 11 WIMAX LTE Downlink ITE hPL porn CE LTE Uplink Status Register rsspecan Exp Fig 2 4 Rohde amp Schwarz Spectrum Analyzer driver in LabVIEW palette view under Instrument I O gt Instrument Drivers gt Rohde amp Schwarz Spectrum Analyzer Palette menu node pictures e g Configuration are stored in dir mnu files in every driver folder and sub folders The tree structure in the palette corresponds to the help file Microsoft compressed html file format chm provided for every Rohde amp Schwarz driver 2 1 3 1 LabVIEW driver types EY rsspecan 3 3 1 LabVIEW Rohde amp Schwarz Spectrum Analyzer driver Help q NATIONAL INSTRUMENTS amp LabVIEW ROHDE amp SCHWARZ Welcome to Rohde amp Schwarz Spectrum Analyzer LabVIEW instrument driver help This help system is intended to provide you with all the information that is necessary for remote control of the R amp S device via instrument driver Please use the navigation tools to the left or directly access the main chapters Why Instrument drivers Supported Environments Supported Interfaces What s new Getting starte
19. FF for critical portions of your measurement with multiple loops do the error check before and right after them The difference between the LabVIEW driver Standard configuration 1st column and LabVIEW driver Express VIs standard operations 2nd column is caused by Initiate vi which is doing additional operations besides sending INIT WAI SCPI command string clearing the instrument error queue temporarily changing the session based measurement timeout When you use Express VI with RSSPECAN ATTR INIT instead you will achieve the same measurement times in both cases In HiSLIP LabVIEW driver Express Vis Standard operations with Error Checking OFF are only cca 5 slower than Visual Studio 2012 C In VXI 11 this difference grows to cca 28 It is safe to say that when it comes to communicating with instruments over VISA Lab VIEW in raw write read mode is as fast as other programming languages When using the Rohde amp Schwarz LabVIEW drivers Express VI with Fast Operations can bring the performance very close to raw write read mode Of course the communication with instruments is only one part of measurement appli cation comparing the overall performance including user interfaces graph and data handling is the topic beyond the scope of this Application Note It is also fair to men tion that the performance comparison was done on relatively powerful PC The results can differ depending on the used computer Therefore we encourage the
20. How to use Rohde amp Schwarz Instruments with LabVIEW Application Note Having the possibility to remotely control instruments has become the necessity not only in the field of automated production testing but more and more already in the phase of development One of the pro gramming environments that makes this task accessible for designers with very little or no programming experience is LabVIEW To make the remote control of instruments easier Rohde amp Schwarz provides the LabVIEW Instrument drivers that take away the burden of controlling synchronization response format ting and error handling from the developer This paper explains how to use Rohde amp Schwarz instruments together with LabVIEW in order to prepare an automated measurement task quickly and efficiently It focuses mainly on using Rohde amp Schwarz Lab VIEW Instrument drivers in addition in several occasions it also shows comparisons with the approach of raw SCPI communication The Application note comes with two Quick Drop plugins for LabVIEW One integrates searching for a desired instrument command the second one automates the Block Diagram connection and alignment of driver subVIs Note Please find the most up to date Application Note on our homepage www rohde schwarz com appnote 1MA228 Instrument Drivers LabVIEW 1MA228 4e Miloslav Macko Application Note h O O N O aA A Q N Contents MT OGG HON acna A EEA EESE 3 About LabVIEW
21. I command string also checks for instrument errors This way you can isolate groups of SCPI commands that have caused an error The following string also available in Direct cmd out 2 is sent to the instrument DISP WIND TRAC1 MODE MAXH DISP WIND TRAC2 MODE MINH SENS FREQ CENT 254000000 000000000000 SENS FREQ CENT STEP LINK RBW SENS FREQ SPAN 12000000 000000000000 SENS FREQ CENT STEP LINK Direct cmd out 2 Center Frequency Coupling Set all defined traces oO Trace Types JE Center Frequency 254 0M cx a ar a Fig 5 17 SCPI command string building with several Fast Compose operations and one Fast Read operation at the end together with Error Checking Center Frequency Coupling 2 RBW 032 F ia Performance comparison Attached files LabVIEW programs Performance comparison Standard Fast Raw vi e Scripts Spyder PlainVISA WriteRead py e Vo programs PlainVISA WriteRead PlainVISA WriteRead sin This chapter contains comparison of performances achieved by using different approaches in LabVIEW and in other programming environments The following test steps were evaluated e IDN loop time measurement 10000 cycles of sending IDN query and read ing the response from instrument This task is not performed when using the Lab VIEW driver since this feature is not available e Configuration time measurement setting 8 different parameters t
22. OF IVGFSisiscscscisseccaiscccsecssnsancesaneatsscanvcivacmeyscemencessneusnvecences 4 Getting started with using attribute based driversS ccsseeeeeee 9 Quick Drop PIUGINS sesen nnn E 14 DIVE EXPESS Vh rirnpean an EAA E 20 Performance COMPATPISON cccccececeeeeeeceeeeeneeeeseneeeneeeeeeneseneseneeeesones 39 THS aA TCR S oiri E AA 43 Additional INTOPMALON vocsieccascesecsesnssesssressscecesesnscctvewssacesextessseasavesexcessis 51 Rohde amp CNW AU 2 asic ts ss stertereeren seers sate esianae sn pada ndcdanasnetioneniaeeaaceunialennies 52 1 1 1 1 2 Required Software Introduction Rohde amp Schwarz provides a range of free Instrument Drivers further referred to as drivers follow the link Rohde amp Schwarz drivers to simplify the development proc ess of instrument remote control applications Among them are LabVIEW attribute based drivers These drivers utilize the Express VI technology which internally takes advantage of VI scripting programmatically creating and modifying VIs In all new Rohde amp Schwarz drivers releases we introduce the Fast Read and the Fast Write possibility This feature removes one common disadvantage that has discouraged users from using drivers speed of execution More about this topic is discussed in chapter 5 Driver Express VI on page 20 and chapter 6 Performance compari son on page 39 For demonstration purposes the Rohde amp Schwarz LabVIEW driver for Spe
23. Query T Do Query Reset Device T Reset Device dup VISA session ft dup VISA session Fig 2 2 Example of dil based RSUPV driver 2 1 3 Attribute based driver This type is the newest one that is also the subject of this Application Note Instrument functionalities are split into attributes which can be set or read separately using Attrib ute Express VIs further referred to as Express VI Configured Express VIs Express VI instances are used in the driver Hi level functions see the example of such Hi level function below In occasions custom LabVIEW code is used when the desired Application Note Instrument Drivers LabVIEW 1MA228 4e 5 LabVIEW driver types functionality cannot be performed by attributes for example reading the analyzer trace setting reading a property that contains a cluster of parameters Installation Copy both folders instr lib and user 1lib to c Program Files x86 National Instruments LabVIEW 2010 Folder instr 1ib contains the driver Hi level functions user 1ib contains the driv er s attribute Express VI It also contains the Crosslinks bin file which is an index ing file used by Quick Drop SCPI command searcher plugin Refer to chapter 4 1 SCPI command searcher plugin on page 15 for more details Example of an attribute based driver Hi level function for setting center frequency and span using two Express VI instances enclosed by red rectangle TA Rohde amp Schwarz
24. Variable RepCap Terminal on VI top Variable RepCap Rings with Dig Display Conditional Terminal Connect Attribute ID terminal Always connect Direct cmd out Use buffered instr handle Input Value Terminal Placernent left Top Bottom z ut Value Terminal Label DescriptrvveName gt lt ValueHRform gt Output Value Terminal Label In lt DescriptrveName gt ional Enum Embedding B2 number Show RSox VAL_ prefix B2 Ring Show numeric value Enum terminal Show SCPI parameter Fig 5 11 Embedding settings tab Embedding settings explanation Variable RepCaps If checked you can choose 1 or more Repeated capabilities e g Trace Marker etc to be variable during the run time RepCaps string in this case must contain a valid Repeated capabilities string even for standard Read Write opera tions which will be taken as a default value Express VI instance will contain additional Ring input s for Repeated Capabilities with default values taken from RepCaps string View VI as Icon With this setting you can define whether to embed the Express VI instance as an icon This checkbox is a 3 state control therefore you can also define not to change the previous settings Variable RepCap Terminal on VI Top With this checkbox you can define whether to connect variable RepCaps terminals on Express VI instance connector top or bottom Variable RepCap Rings with Dig Display Sets the visible Digital Displa
25. Y F0 F0 F F F F F F F F F User Libraries Exoress User Libraries 4 Express User Libraries specan Fa T 5 rsspecan rspecan_core i ttribute_express Source vi Fig 5 2 The Express VI instance can be placed in the Block Diagram by Functions palette gt User Libraries gt Express User Libraries gt rsspecan gt rsspecan Expr VI e Copying from existing code Use the driver Hi level function e g figure 2 3 to copy the instances of Express VI from Copying the Express VI instance also cop ies its configuration Rich text VI title will be replaced by plain text because Lab Express VI in drivers VIEW will add an index number at the end of the title to distinguish between the instances You have to run the Configuration panel to get it back to rich text title Using Palettes or Quick Drop will immediately invoke Configuration panel linked to Express VI To disable this go to Menu gt Tools gt Options gt Block Diagram and uncheck the checkbox Configure Express VIs immediately Block Diagram New and Changed Front Panel General Controls Functions Palettes i Environment Place front panel terminals as icons Search Place structures with Auto Grow enabled Paths Printing Configure Express VIs immediately Menu Shortcuts Auto insert Feedback Node in cycles Tip Strips and Labeling V Show tip strips over terminals Use control caption for subVI tip strips
26. agram and invoke SCPI com mand searcher it will automatically select the proper driver and search for the ele ments that are related to the Express VI instance attribute In the picture below the attribute RSSPECAN ATTR SWEEP MODE CONTINUOUS shows that is used in e g Configure Aquisition vi function and sends the INIT CONT SCPI com mand LSS aa ea ens Application Note Instrument Drivers LabVIEW 1MA228 4e 15 Connect and Align plugin ive Display Update OFF Sweep Time 3 0 Ca Coons VISA resource name Search in Functions GE RSSPECAN_ATTR_SWEEP_MODE_CONTINUOU SES m Bluetooth Analyzer Configuration Configure BTO Acquis Search in Attributes iy Configuration Configure Acquisition vi O Monitor Clipboard INIT CONT Search for the name o INITiate CONTinuous ON OFF NTI Js RSSPECAN_ATTR_SWEEP_MODE_CO NUOUS Fig 4 2 SCPI command searcher invoked with selected driver Express VI function e If you select the driver Hi level function on your Block Diagram and invoke SCPI command searcher it will automatically select the proper driver and search for the elements that are related to the Hi level function In the picture below the Hi level function Configure Acquisition vi uses two attributes and 2 SCPI com mands two for each attribute one form is used in the instrument manual the 2nd is actually sent by the driver Display Update OFF VISA resource name CONFIG 170 Sweep Time 3 0
27. alette The right click context menu allow for open ing element Help topic copying as text showing the element on Palette and opening a folder containing the selected element Dragging and Dropping the Attribute ID to your Block Diagram will invoke the Express VI Configuration Window with pre selected Attribute ID y aad Quick Drop i NLGmath lvlib on vi NI_Gmath lvli Riemann Zeta Function vi NI_Gmath lvlib NET Object To Variant vi 1D ANOVA vi NLAALPro Ivlib v Shortcuts Help CPL amd search veon a20 j 28 285 Results as Search in Functions F FREQ CENTer CCfcci a mf LTE Uplink Configuration IQ Measur ments Signal Characterig Search in Attributes SENSe FREQuency VERify TOLerance E 4 RSSPECAN_ATTR_LTE_UPLINK_CARRIER_FREQUENCY_CENTER J Monitor Clipboard SENSe FREQuency VERify STATe ON Display Symbol Search forthe SCPIcommand ap SENSe FREQuency VERify STATe ON Show Help SENSe lt 1 2 gt FREQuency STOP ae SENSe lt 1 2 gt FREQuency STARt aa co SENSe FREQuency TRACkON OFF Show On Palette Open folder in file explorer Search Fig 4 1 SCPI command searcher window The configuration of the Express VI is described in the next chapter The SCPI command searcher also allows for the following functionalities e If you select the driver Express VI on you Block Di
28. bel for variable input value terminal Output Value Terminal Label This string control can use the same variables as Title compose string table 5 1 without rich text capabilities Double click to compose the settings The result name will be used as a label for output value terminal Enum Embedding Terminal Type You can decide how to embed Enum Data types as 132 number 132 Ring or Enum terminal This settings is common for input and out put value terminals Enum Embedding Show RSxxx_VAL_ prefix If you use embedding of Enum Data Types as 132 Ring or Enum you can decide whether to have item names with RSxxx_VAL_ prefixes Sometimes the names are too long so cutting this part out makes the items more compact Enum Embedding Show numeric value If checked the item names start with their integer value in round brackets Enum Embedding Show SCPI parameter If checked the item names end with actual SCPI parameter in square brackets Changing Show RSxxx_VAL_ prefix Show numeric value or Show SCPI parameter when you have the attribute with Enum Data Type selected will immediately alter 11 Input Value Ring items This way you can see how item names will look in your code As an embedding example open the attached file LabVIEW programs Example EmbeddingSetTrace vi It shows the Express VI instance with the attribute RSSPECAN ATTR TRACE TYPE and the following Embed ding options E Application Note Instrument Drivers LabVI
29. ble readable will be shown 3 state checkbox Write Callback Read Callback search based on attribute prop erty of special function for writing or reading Some attributes cannot use standard value data types of 132 Double Boolean String therefore they need special function called Callback As a consequence Fast Write Read operations cannot be used with such attributes If this checkbox is checked only the attributes for which Write Read callback is defined will be shown 7c Filter tab Filter tab allows to only see the attributes in Select Attribute control that fulfill the Filter Specification Main filter switch is the control 4 Filter figure 5 6 It will be automati cally checked on when the Filter Specification changes from its default value Filter specification control is the same as in 7b Find Tab 7d Main Nodes tab By selecting only a portion of Main Nodes you can select only branches of Attributes tree that are of interest to you Selecting a portion of the main nodes automatically checks the 4 Filter on By default all Main Nodes are selected Multiple items selec tion is possible with CTRL or SHIFT E Application Note Instrument Drivers LabVIEW 1MA228 4e 31 Express VI Configuration panel 5 3 2 5 7e Embedding tab This tab contains the setting for Express VI instance embedment into the Parent VI Hi Level Functions About OOOO O E Variable RepCaps F View VI as Icon Marker a
30. chapter describes the driver Express VI used for setting the driver attributes This Express VI is a part of a rsidr_toolbox library and will be commonly used by all instal led Rohde amp Schwarz drivers The rsidr_toolbox library is installed with the first use of Express VI Configuration panel or you can install it manually refer to chapter 4 Quick Drop Plugins on page 14 Why should you use Attributes Express VI There are several reasons to do so e Performance The driver even with ErrorChecking switched OFF chap ter 3 1 1 2 Instrument Status Checking vi on page 11 still has an overhead which in certain applications may prove too high For these cases Express VI offers Fast Write and Fast Read operations that compose most of the SCPI command during the configuration phase If you use fixed input parameter value the entire SCPI command string is prepared just to perform VISA Write operation during the execution Also rather than sending SCPI commands one by one they can be composed into one string and then sent all at once to the instrument Read more in chapter 5 2 Express VI in drivers on page 22 and chapter 6 Performance comparison on page 39 Reading attribute parameter value Due to a large number of attributes the driver doesn t provide all Hi level functions for retrieving attribute values For exam ple you can set the spectrum analyzer center frequency with Configure Frequency Center vi but there is no fu
31. ctrum Ana lyzers rsspecan is used in this Application Note However the presented procedure is applicable to all Rohde amp Schwarz drivers The Spectrum Analyzer driver is chosen because it represents the most comprehensive application when communicating with any other instrument settings waiting for the measurement result reading the results either in strings or arrays of numbers Microsoft and Windows are U S registered trademarks of the Microsoft Corporation R amp S is a registered trademark of Rohde amp Schwarz GmbH amp Co KG National Instruments are U S registered trademarks of National Instruments LabVIEW is a trademark of National Instruments Required Software To follow the steps described in this Application Note the following software is required e Windows XP Vista 7 32 bit 64 bit operating system e LabVIEW 2010 or later 32 bit 64 bit e VISA I O library e g National Instruments VISA Version 5 x The configuration used in for this Application Note Windows 7 64 bit LabVIEW 2010 32 bit NI VISA 5 4 0 used driver in all examples is rsspecan LabVIEW driver version 3 3 1 R amp S Instrument driver toolbox rsidr_toolbox version 4 2 0 Related Documents The Application Notes discussing remote control drivers and their usage e 1MA153 Development Hints and Best Practices for Using Instrument Drivers e 1MA170 Introduction to Attribute Based Instrument Drivers LabVIEW driver types 2 About
32. d by speed from the slowest to the fastest w N N wi Measurement time in seconds un tn Qo LabVIEW driver LabVIEW driver Spyder Python LabVIEW driver LabVIEW Visual Studio 2012 C Standard configuration Express Vis with PyVISA Express Vis raw VISA write read Standard operations Fast operations E Error Checking ON additional time E Error Checking OFF Fig 6 2 HiSLIP duration time results of Measurement task Performance comparison 6 3 Conclusion When using the LabVIEW driver switching OFF the Error Checking can significantly reduce the measurement time over 30 in VXI 11 over 20 in HiSLIP in our mea surement task The absolute time spent on one error checking task is in our setup cca 1 9ms VXI 11 resp 1ms HISLIP The downside of Error Checking switched OFF is that you cannot react on an error occurred in the instrument which can lead to although fast but inaccurate or invalid measurement results The best approach is to do the Smart Error Checking Keep Error Checking ON for sections of your program that are not performed in multiple loops Keep Error Checking ON for multiple measurement loops where the instrument measurement times are relatively long long sweep times averaging results etc The longer measurement time you have the less significant is the Error Checking time By sweep times in range of seconds the Error Checking time is negligible e Switch Error Checking O
33. d RepCaps Composing of this string is made easy by a table with only valid val ues allowed Driver structure 3 Getting started with using attribute based drivers 3 1 Driver structure The LabVIEW driver consists of a multi level folder and file library forming a tree struc ture that corresponds to the help file Contents node Instrument Driver Tree Structure or shortly VI Tree This structure is also reflected in lt driver name gt VI Tree vi The root folder is different for a project based drivers newer type and previously used non project based drivers Project based drivers have no lt driver name gt prefix for the Vis because the driver prefix is the name of the project they are members of They contain 2 folders Private and Public Private is reserved only for internal driver use Public is the root folder for the user Non Project drivers have lt driver name gt prefix for all Vis and there are no restrictions to the availability of VIs lt driver name gt folder is the root folder for the user The following files can be found in the user root folder VI names mentioned here are without lt driver name gt prefix driver help file lt driver name gt chm rsspecan chm Microsoft CHM file that gives an overview of the driver structure Hi level functions attributes by linking the driver s attribute help file mentioned below additional driver information driver s attribute help file lt driver name
34. d and Examples Instrument Driver Tree structure Alphabetical list of Vis Contact Install and how to use this help We also invite you to find out what s new in the current revision of the instrument driver If you have any questions or comments please contact your partners at Rohde amp Schwarz and give us your feedback Noise Figure and Gain Measure Phase Noise Trade names are trademarks of the owners bai ra a EMI Maso ramant Annliestinn gt Copyright 2014 Rohde amp Schwarz GmbH amp Co KG Last updsted December 04 2014 Fig 2 5 Rohde amp Schwarz Spectrum Analyzer driver help file rsspecan chm Repeated Capabilities in Attribute based drivers Many instruments contain multiple instances of the same type of functionality For example many instruments have multiple channels windows or traces with independ ent settings The general term for functionality that is duplicated in an instrument is repeated capability An instrument may have multiple sets of repeated capabilities such as windows and traces or markers Repeated capability instances are specified by a string parameter to each function that accesses the repeated capability To define the usage of a particular capability fill the string with a proper value To use more than one repeated capability in one attribute separate them with comma In the driver Express VI Configuration panel the input string control for Repeated Capabilities is calle
35. e columns allow for full text searching in attribute fields All non empty Driver Express VI 9 3 2 3 9 3 2 4 strings must fulfill the attribute specification otherwise they will not be positively matched The text field SCPI command uses a special search method that is the same as in Quick Drop SCPI command searcher plugin to ensure the best results when search ing for a SCPI command lf Case Sensitive checkbox is checked all non empty strings except SCPI com mand are evaluated with case sensitivity lf Regular Expr checkbox is checked all non empty strings except SCPI command are considered LabVIEW regular expressions Data type checkbox switches search based on attribute value data type Multiple items selection is possible with CTRL or SHIFT 3 state checkbox RepCaps search based on the attribute property Repeated Capa bilities If checked only the attributes with at least one RepCap defined are shown 3 state checkbox Range Check search based on the attribute property of value range checking If checked only the attributes that have a defined range for their value will be shown 3 state checkbox Hi Level Fncs search based on the usage of attribute in a Hi level function If checked only the attributes that are used in at least one Hi level function will be shown 3 state check boxes Write Access Read Access search based on attribute prop erty of access If checked only the attributes which are writa
36. e use on page 47 Below the Configuration panel is described in detail dih RtFast Marker Amplitude M1 Express VI Configuration panel Attribute All 3701 E Flatten C Filter Find All Descriptive Name Identifier without prefix Range Raw command without Data Type Hi Level Functions po pee Frequency Offset FREQUENCY_OFFSET 100 0 SENS FREQ OFFS Double lt R gt Configure Frequency KEJ i Frequency Stop FREQUENCY_STOP SENS FREQ STOP Double 4 Configure Frequent CFGEVI VItitleComposeString i Center Frequency Step Auto FREQUENCY_STEP_AUTO SENS FREQ CENT STEP AUT Boolean Configure Frequency lt b gt lt red gt lt ResultCmdNoParam gt lt red gt lt purple gt o pee Center Frequency Coupling FREQUENCY_CENTER_LINK 4 SENS FREQ CENT STEP LINK Enum lt R gt 2 Configure Frequent oe Frequency Span FREQUENCY_SPAN SENS FREQ SPAN Double 2 Configure Frequent VI Title preview p Full Frequency Span FREQUENCY_SPAN_FULL SENS FREQ SPAN FULL lt none gt Configure Frequency Horizontal Scale HORIZONTAL_SCALE 2 DISP WIND TRAC X SPAC Enum lt R gt Configure Horizontal amp Marker 88 6N 9E p Marker State MARKER_ENABLED CALC MARK Boolean 2 Configure Marker v E ae ioo fees ie Frequency Start FREQUENCY_START SENS FREQ STAR Double 4 Configure Frequent vow Center Frequency FREQUENCY_CENTER SENS FREQ CENT Double 7 Configure Frequent lt b gt lt Ope
37. ep mode Always keep your analyzer class device in single sweep mode For that in the rsspe can driver use the attribute RSSPECAN ATTR SWEEP MODE CONTINUOUS or Hi level function Configure Acquisition vi Initialize and Continue measurement Starting the measurement on spectrum analyzer is performed with the attribute RSSPECAN ATTR_INIT or Hi level function Initiate vi If you don t want to clear the previous Average MaxHold MinHold results use the attribute RSSPECAN ATTR INIT CONMEAS or Continue vi Both Initiate vi and Continue vi send WAI at the end which assure that if you send any query immedi ately after them the query will be processed only when the measurement sweep is fin ished Therefore your query will return a result from the last sweep Preventing measurement Timeouts Synchronization method used by the Rohde amp Schwarz drivers is OPC STB poll Therefore changing VISA Timeout parameter will not help avoiding timeouts for long measurements Use Utility Vis to set get the STB poll timeout value chapter 3 1 1 6 Get Timeout vi Set Timeout vi on page 13 Tips when using drivers 7 3 9 Reading and Fetching measurement results Vis that have Read in their names start a new measurement and then read the results If you don t want to start a new measurement use Fetch VIs They only read the val ues obtained by the last measurement 8 Additional Information Please send your comments and suggestions regardin
38. g this Application Note or Attrib ute Express VI to TM Applications rohde schwarz com Using tag 1MA228 in the mail subject will help us to quickly identify the topic and speed up the response process 9 Rohde amp Schwarz Rohde amp Schwarz is an independent group of companies specializing in electronics It is a leading supplier of solutions in the fields of test and measurement broadcasting radiomonitoring and radiolocation as well as secure communications Established more than 80 years ago Rohde amp Schwarz has a global presence and a dedicated service network in over 70 countries Company headquarters are in Munich Germany Sustainable product design Environmental compatibility and eco footprint e Energy efficiency and low emissions e Longevity and optimized total cost of ownership Certified Quality Management Certified Environmental Management ISO 9001 ISO 14001 Regional contact e Europe Africa Middle East Phone 49 89 4129 12345 customersupport rohde schwarz com e North America Phone 1 888 TEST RSA 1 888 837 8772 customer support rsa rohde schwarz com e Latin America Phone 1 410 910 7988 customersupport la rohde schwarz com e Asia Pacific Phone 65 65 13 04 88 customersupport asia rohde schwarz com e China Phone 86 800 810 8228 86 400 650 5896 customersupport china rohde schwarz com Headquarters Rohde amp Schwarz GmbH amp Co KG Muhldorfstrake 15 D 81671 Munchen 49
39. g this operation Fig 5 9 Standard Read Icon Application Note Instrument Drivers LabVIEW 1MA228 4e 27 Driver Express VI e Write Set Standard driver write method All write functions in driver are pro grammed using this operation e Fast Read GetFast Fast read operation command is prepared during configura tion Run time action is limited to writing prepared string to instrument reading the response from instrument and converting the response to defined attribute type You can use Error Checking with this operation E e Fast Write SetFast SetFix with Send To Instrument checked Fast write opera tion to the instrument If you don t need to change the attribute input parameter dur ing run time check Fixed input parameter checkbox Available post operations WAI OPC and Error Checking e Fast Compose BuildFast BuildFix with Send To Instrument unchecked This operation doesn t communicate with the instrument It only composes the com mand and returns composed string in Direct cmd out which can be connected to the next Express VI instance Direct cmd in input This way you can compose the list of parameters which will then be sent to the instrument all at once If you don t need to change the attribute input parameter during run time check Fixed input parameter checkbox Available post operations WAI 5 3 2 7a 7f tab control tabs 5 3 2 1 7a Title composer tab This tab defines the compose
40. hronisation check boxes this variable can have values lt empty gt WAI OPC WAI OPC Table 5 2 Title compose string formatting tags Pair tags lt b gt lt i gt Bold and italic text e g lt b gt This is bold lt i gt plus italic text lt i gt lt b gt and this is normal text Pair tags for colors lt red gt lt blue gt lt green gt lt yel Applies a color to a text between tags low gt lt pink gt lt purple gt lt orange gt lt white gt 5 3 2 2 7b Find tab Hi Level Functions Filter Main Nodes Embedding Find Specification Data type Descriptive Name CTRL G B2 marker Double string Attribute ID CTRL H Boolean Eventlype di SCPI command CTRL F Enums E RepCaps Po E Range Check B Hi Level Fncs B Write Access B Read Access B Write Callback B Read Callback Case Sensitive Regular Expr find Ne F Fig 5 10 Attributes Find tab Find tab allows you to find an attribute based on Find Specification control Search ing of the next item fulfilling the criteria can be done with Find Next button or F3 or ENTER button when focused on one of the string fields You can see all positive search results in Select Attribute control when checking 5 Find All checkbox fig ure 5 6 Use the shortcuts e g CTRL G CTRL H CTRL F to quickly focus on the string fields String fields Descriptive Name Attribute ID and lt Variable field gt depending on Select Attribut
41. ing drivers In this chapter you will find useful tips when working with Rohde amp Schwarz drivers Use Quick Drop plugin SCPI command searcher SCPI command searcher provides a full integration of SCPl custom searching proce dure for an attribute function with the certain SCPI command and direct Drag amp Drop to your Block Diagram Refer to chapter 4 1 SCPI command searcher plugin on page 15 for more details Use Quick Drop plugin Connect and Align This plugin will automate your Block Diagram editing by connecting and aligning termi nals and nodes together Refer to chapter 4 2 Connect and Align plugin on page 16 for more details Mass compile your driver before the use Rohde amp Schwarz drivers are compiled in LabVIEW 2010 32 bit If you use higher ver sion of LabVIEW it is the best to perform Mass Compile of the entire driver folder before using it Mass compiling of a big driver like rsspecan can take some time but you only need to do it once After copying instr 1lib and user 1ib driver folders to your LabVIEW folders start LabVIEW go to menu Tools gt Advanced gt Mass Compile in Directory to compile navigate to instr lib Rohde amp Schwarz Spectrum Analyzer and press Mass Compile button 7 3 4 Tips when using drivers di Mass Compile Directory to compile 4 Lookin J Rohde amp Schwarz Spectrum Analyzer Q2 PE Name m Date modified Type 4 Private 05 01 2015
42. ing the folder in the File Explorer e Showing the Hi level function help e Switching to other attributes that are used in this Hi level function 5 3 2 8 7h Info The various information about the selected attribute An example for RSSPE CAN_ATTR_MARKER_POSITION Attribute name Marker Amplitude Attribute path Marker Marker Amplitude Data type Double Access Read Write Attribute ID RSSPECAN ATTR MARKER AMPLITUDE SCPI command CALC MARK Marker Y SCPI command from help CALCulate lt l1 2 gt MARKer lt l to 4 gt yY Supported Instruments Repeated Capabilities Marker 5 4 Example of LabVIEW Express VI code Marker Detix 0 MIM 1 M2 2 MS 3 4 TMA 4 MS 9 PMG COs y eT eT y M8 0 5 M9 9 MLO LO 5 Pe 11 Me 1L2 y MLO CS yy LA 14 PMS RS OMe 6 Hi level function names Query Marker vi Example of LabVIEW Express VI code Attached file LabVIEW programs Example Express vi This code opens the VISA session to the analyzer configures the analyzer to single sweep with 10 maxhold and minhold sweeps you can add more traces Then it reads X and Y traces and displays them in XY graph Notice the different approaches of com munication with the instrument Building the SCPI command string with several Fast Compose BuildFast BuildFix operations and at the end use Fast Write SetFast operation As a result only the last VI communicates with the instrument Thi
43. llib A default RS_toolbox vi 1D Linear Evaluation PtByPtwvi 15 toolboxkxVIidefault vi es 7 eS RS toolboxExVIsCustom vi Straighten TheWireDown vi Straighten TheWireLettwi StraightenTheWireRight wi StraightenTheWireUp vi Shortcut Press Key Selected Plugin Description no description available L anes Gatto If a desired shortcut is already occupied you will have to change it directly in the C Program Files x86 National Instruments LabVIEW 2010 LabVIEW ini file Key name QuickDropKeyboardShortcutMappings Quick Drop Plugins 4 1 SCPI command searcher plugin Default keyboard shortcut CTRL F After CTRL SPACE The SCPI command searcher will scan all the installed drivers for the indexing file called Crosslinks bin and give you a selection of the available ones You can search for either a SCPI command or an attribute function name The SCPI command search uses a special matching method based on the SCPI commands syntax so the commands can be in short form long form copy and paste directly from a device user manual non mandatory parts can be skipped and so on The matching results will be displayed in the middle listbox After selecting the SCPI command of your choice the right listbox will contain all the functions and attributes that use this SCPI command Simply Drag and Drop the desired element to your Block Diagram Alternatively use the double click on the ele ment to show it on the Functions P
44. nction to read it back Here you have to use Express VI configured to Read operation with the attribute RSSPECAN_ATTR_FREQUENCY_ CENTER Setting just one attribute parameter separately The driver Hi level functions are very often programmed with certain logic inside they group setting of several attributes together If you just wish to set one attribute you have to use Express VI e Non availability of Hi level function To minimize the size the new Rohde amp Schwarz drivers are missing Hi level functions that set just one attribute There are some exceptions to this for legacy reasons or IVI specification requirements If you cannot find a Hi level function using the attribute you need you can always access it by Express VI 5 1 General principle of LabVIEW Express VI A Express VI consists of 3 parts e Execution Code VI VI with the actual execution code during the run time e Configuration VI this VI is invoked when you double click on any Source Express VI instance in your code The Configuration VI has a front panel and based on the settings it will modify the content of that Source Express VI instance e Source Express VI this is the VI we refer to as Express VI If you place the Express VI into your code you create anExpress VI instance Source Express VI with a certain configuration and this is what you see in your code In principle it s a wrapper over the Execution Code VI with configurable content inputs ou
45. nds the SCPI query STB after each command query checks the bit 2 of the Sta tus register Error Queue not empty and reports an eventual errors to the error cluster Set this parameter to OFF for sections of your code that require fast execution speed Refer to chapter 6 Performance comparison on page 39 Option Checking vi This VI changes the session based parameter OptionChecking which is set to ON during initialization Some instrument commands require certain software or hardware options to be available The driver checks whether a required option is available on the instrument before it sends the command Configure Error Checking vi AEREE COHF IG This VI combines the settings of both previous VIs plus the RangeChecking settings which is set to ON during initialization Switch the RangeChecking off in special cases when you are sure your instrument accepts the values outside the range allowed by the driver _check_error vi SC ERROR This VI is used to detect whether an instrument has any message in its error queue First the VI sends SCPI query STB and checks the bit 2 Error Queue not empty If this bit is set to 1 SYST ERR reads and deletes the 1st entry from instrument error queue If you used Instrument Status Checking vi to set the ErrorChecking to OFF there might be more than 1 errors in the queue Therefore in order to delete all the error messages you must call this VI in a loop until it reports
46. o the instru ment e Measurement 10000 cycles of triggering the short sweep 50us in zero span waiting for the sweep to finish reading the RMS marker reading marker X and Y coordinates All used programs and scripts are available in attachment of this Application Note All measurements are performed using VXI 11 and HiSLIP protocols The following approaches were chosen for comparison e LabVIEW driver Standard configuration and measurement functions e LabVIEW driver Express VIs configured to Standard operations e LabVIEW driver Express VIs configured to Fast operations e LabVIEW raw VISA write read e Visual Studio 2012 project in C with visa32 d11 e Spyder Python script with raw VISA communication using PyVisa component Test setup e Dell Optiplex 7010 17 3770 3 40GHz OS Win7 64 bit 16GB RAM e Network adapter Intel PRO 100Mbit LAN switch 100MBit e Instrument Rohde amp Schwarz FSW26 firmware 2 00 e LabVIEW 2010 32 bit e LabVIEW driver rsspecan 3 1 0 07 2014 e Visual Studio Professional 2012 Version 11 0 51106 01 Update 1 NET framework 4 5 50709 Spyder 2 2 5 with Python 2 7 6 32 bit 6 1 Results using VXI 11 protocol Results using VXI 11 protocol Table 6 1 Result table for VXI 11 protocol EC OFF means that Error Checking was switched OFF IDN loop time in sec Configuration time in Measurement time in onds seconds seconds N A LabVIEW driver Stand ard configuration 0 07 0 04
47. oordinate of an object in the selection e The connection and alignment works not only on the driver Vis but on all nodes with error in out terminals VISA terminals are optional e If anode doesn t have a VISA terminal the plugin tries to find a next node or termi nal of the VISA type see the example pictures below e By default the Y alignment is done according the most left object in the selection Using CTRL SHIFT A changes that to the most right selected object e The plugin also works without any nodes just on tunnels and or control terminals e Wiring through tunnels is done in a smart way if a tunnel is in your selection it will be reused instead of creating a new one which would lead to a parallel tunnel that is hard to spot e fa Case Structure Selector is in the selection the error cluster will be rewired through it and all existing connections inside all case diagrams will be maintained The same rule applies for Shift Registers Here are some before and after pictures showing the plugin capabilities First you need to perform a selection either by area or selecting individual objects Then invoke the Quick Drop by CTRL F and run the plugin by CTRL A e Connecting terminals with the driver VIs The left most node error terminal or error tunnel is used as for Y alignment s lerror out W4 respurce name error in no error L k Selecting the new nodes and the error VISA wires that star
48. orter than the duration of the sweep otherwise your analyzer waits idle Not to lose time and find out whether measurement result is already available you have to use OPC STB poll synchronization method OPC query Attached example LabVIEW programs Example synchronization OPCquery vi Querying write read OPC makes your application to wait until the instrument responds with 1 or 0 if error occurred after all previous operations were finished Attached example shows the same task as in case of WAI but using the OPC query You need to set the VISA timeout parameter to higher value than the duration of your measurement E Application Note Instrument Drivers LabVIEW 1MA228 4e 45 Tips and Tricks 7 2 3 OPC STB poll Attached example LabVIEW programs Example synchronization OPC amp STBpoll vi Instrument s Event status register ESR provides an event like reading the value clears it information about the instrument status Its bit O Operation Complete is set to 1 when all the previous operations have finished If you set the Event status enable register ESE bit 0 to True Operation Complete event will be reported in the Status register STB bit 5 ESB see the figure below The driver sets the ESE bit 0 to True in Intialize vi amp logie AND bgt OR of all bits T A 5 4 3 2 1 0 Power on User Request Command Error Execution Error Device Dependent Error Query Error Operation Complete
49. r string based on which the result Express VI instance title will be composed This composer string is unique for every Express VI instance It is a multi line string that contains fixed portions variables e g lt DescriptiveName gt and formatting pair tags e g lt b gt BoldText lt b gt You can double click on this control Application Note Instrument Drivers LabVIEW 1MA228 4e 28 Driver Express VI eee aa Se aS to use the composer window or modify it directly VI title preview shows how the result VI title will look like for the current configuration You can also change the Background color of the title this is useful to e g distinguish between the different instruments by setting a unique title background color Limiting the title width prevents the long description names causing the big horizontal space taken by the Express VI instance on the Block Diagram You also have a possibility to change the default title position Below is the list of available variables and formatting pair tags Table 5 1 Title compose string variables DescriptiveName Descriptive name of attribute e g Averaging State Whole Attribute identifier e g RSSPE CAN_ATTR_AVG_STATE IdentifierNoPrefix Attribute identifier without lt driver_ name gt _ATTR e g AVG_STATE Operation Attribute operation Get Set GetFast SetFast BuildFast SetFix BuildFix Refer to chap ter 5 3 1 8 Attribute operation control on page 27 DataType Attrib
50. r to Always Included group In order to see the Rohde amp Schwarz Spectrum Analyzer lvlib in Project Files you need to have it added to MyApplication lvproj If your instrument driver is not project based add its utility callbacks folder to MyApplication lvproj in order to access it If you are using more than one driver you will need to repeat this procedure for each of them Synchronization methods Synchronization of your application and your measurement instruments is a crucial part of every automated measurement task Programmer always has to know in which state his instrument is when he applies a stimulus or reads the measurement results Using Tips and Tricks 7 2 1 7 2 2 instrument locally and observing measurement results visually is in this aspect very dif ferent from operating it remotely While in local operation user s eye serves as a flag to distinguish between already valid result and measurement still in progress remote control application must rely on instrument s build in synchronization mechanisms Although the measurement synchronisation is mostly related to analyzer class instru ments spectrum analyzers oscilloscopes audio analyzers multimeters the same principles can be used also for other instrument types Keep in mind that in order for synchronization to be working properly your instrument must be in single sweep single measurement mode Below there are three basic synchronization methods you can u
51. ration gt lt b gt lt DescriptiveName gt lt RepCapNE gt Center Frequency Step FREQUENCY_CENTER_STEP SENS FREQ CENT STEP Double Configure Frequency Attr lt b gt lt IdentifierNoPrefix gt lt b gt lt ValueHRform3 gt lt purple gt lt yellow gt lt Sync gt lt yellow gt lt b gt se Center Frequency Coupling Fi FREQUENCY_CENTER_LINK_F 1 100 SENS FREQ CENT STEP LINK B2 lt R gt Configure Frequency Title position Marker Position MARKER_POSITION CALC MARK X Double 4 Move Marker vi Qu VI Title max width VI Title max height er to Trace MAR RACE 1 6 CALC MA c B2 lt R gt Configure Marker vi 350 350 re a sella default er to Trace Raisin ASSI ARKER_TO_TRACE 6 CALC MA C Enum lt R gt Te aa off MARey AOFF CALC MA F lt none gt 2 All Delta Markers O Z Set Title Background color A Bottom left EX Boolean Configure Marker Sear Bottom center ie Marker focal Oscillator Suppr MARKER LOEX CALC MARK O J Send To Instrumen Al T OPC Error Checking w r _ RSSPECAN_ATTR_MARKER_AMPLITUDE SCPI Command H ha gt CALC MARK1 Y 2000000 000000000000 Help update Cancel ESC Fig 5 6 Express VI Configuration panel 1 Select Attribute control This control represents the tree structure of driver attributes same as you can find in rsspecan attr chm Based on the selected attribute
52. s is the fastest way how to set up you instru ment The SCPI command string that has been built and sent is shown in the string control Direct cmd out 1 In our case the SCPI string is SYST DISP UPD OFF INIT CONT OFF SENS SWE COUN 3 WAI Direct cmd out 1 Pabc Display Update OFF Number of Sweeps 3 Fig 5 15 SCPI command string building with two Fast Compose operations and one Fast Write operation at the end Sending the commands with the driver standard Write Set operation Commands are sent directly and Error Checking is performed after every operation There is no differ ence between standard Write operation Express VIs and using the driver Vis because the entire driver is programmed with Express VIs configured to standard Write or standard Read operations Example of LabVIEW Express VI code Resolution Bandwidth 1 0M Video Bandwidth 50 0k Fig 5 16 Standard Write VIs that you can find in all driver functions Similarly to the previous part SCPI command string is built by using Fast Compose BuildFast BuildFix and the end using Fast Read GetFast to retrieve a response from the instrument As you can see SCPI command string can be built by using differ ent methods in our case with shift register over the for loop creating settings for multi ple traces Compared to sending separate command for every attribute this approach takes only a fraction of that time In this example the last Express VI sending SCP
53. s the Configuration panel The instance of this VI you see in your Block Diagram Source Express VI Execution Code VI Plus gt Grey area can be modified by Configuration VI Fig 5 1 Basic structure of Express VI An instance of Express VI is visible in your code Express VI in drivers 5 2 Express VI in drivers The Express VI for the rsspecan driver is located in c Program Files National Instruments LabVIEW 2010 user 1lib _ xXPress rsspecan rsspecan Core attribute Sxpresscource J1b library This library contains Source Express VI and the Execution Code VI that is executed during run time The Express VI has always Source in its name You cannot drag and drop it to the block diagram from IIb limitation of Ilb format You have to use one of the following options to access the Express VI e Using Quick Drop SCPI command searcher refer to chapter 4 1 SCPI com mand searcher plugin on page 15 on how to install it On the Block Diagram press CTRL Space and then CTRL F e Using Instrument I O palette Refer to figure 2 4 e Using User Libraries palette 4 Functions Instrument VO DRIVERS Livi fa Instr Drivers WI Class Driv Instr Asst MW EEL SERIAL S GPIB Serial Programming Measurement P O Vision and Motion Mathematics Signal Processing Data Communication Connectivity Control Design amp Simulation SignalExpress Express Addons Favorites Hi
54. se with Rohde amp Schwarz instruments WAI command Attached example LabVIEW programs Example synchronization WAI vi Sending WAI command makes your instrument not your application to wait until all previous pending commands are completed This method doesn t synchronize instrument with your application it just tells the instrument that you want it to finish all the previously received commands before processing further ones Example of use Send the following string to you spectrum analyzer 1st part of attached example SYST DISP UPD OFF INIT CONT OFF SENS SWE TIME 3 000000000000 SENS SWE COUN 27 WAT INIT WAI gt ee CALC eMARKI MAX sCALC MARKI Y Notice that you can send the entire SCPI string together and because of WAI com mand the instrument will do exactly what you expect Set up wait one sweep wait for it to finish set the marker to max and return you the amplitude WAI assures that you get the marker value only when the sweep is finished and you re not getting an invalid result or a result from previous sweep This process also makes your application wait in VISA Read vi and therefore continue only when the measurement was finished If you want your application to perform other tasks while the sweep is running you have to send the same SCPI command string without the query at the end and only later query the marker amplitude 2nd part attached example In this case your application meantime operation must be sh
55. sweep mode If calculation of average values is active selection between logarithmic and linear averaging is possible For more detail see command SENSe AVERage TYPE Available Repeated Capabilities Trace TRL TR2 TRS TR4 TRS TRG TRY TRE Remote control command s DISPlay WINDow lt 1 2 gt TRACe lt 1 to 3 gt MODE WRiTe VIEW AVERage MAAHold MINHold RMS Detailed help Elele Fig 5 13 Configuration of the Express VI displayed in Context Help window 7f About This tab shows the Express VI version info and the contact information 7g Hi Level Functions If the actual attribute is used in a Hi level function s these will be displayed here For example the attribute RSSPECAN_ATTR_MARKER_POSITION is used in the follow ing three Hi level Functions Express VI Configuration panel VI Title Fi Filter Main Nodes Embedding Hi Level Functions ha Configuration Common Analysis and Display Marker Mowe Marker wi Configuration Common Analysis and Display Marker Query Marker vi 802 1 IEEE 802 11 Configuration Marker Configure WLAN Marker Position vwi amet WIMAX Configuration Marker Contiqure WIMAX Marker Position vi Fig 5 14 Example of the attribute RSSPECAN_ATTR_MARKER_POSITION associated Hi Level func tions Right click context menu allows for e Copying the VI to the clipboard e Placing the VI to the Parent VI e Copying the VI path to the Clipboard Open
56. t left to the selection and end right to the selection will insert the nodes into the chain Application Note Instrument Drivers LabVIEW 1MA228 4e 17 Connect and Align plugin resource name Li oh Brisbane E mand Fe error in no error L h error out VISA resource name error in no error error out e Adding a VI in the middle of an existing chain by selecting also left and right node All the nodes on the right are shifted to make required space resource Name error in no error L24 EET error in no error L VISA resource name e Connecting through a Case Structure with its case selector terminal included in the selection The error cluster is wired through the case selector terminal Notice the VISA tunnels being reused and thus maintaining the other cases of the Case Struc ture properly connected The Property node without a VISA terminal is still connec ted to the error wire Direct cmd in out terminals of Express VIs with are intercon nected as well Connect and Align plugin Connecting through a Loop structure with Shift Register included in the selection resulting in connecting it to the error wire No unnecessary new tunnels are created through the loop structure and the tunnels auto indexing is disabled All the termi nals have labels shifted to left or right to make the diagram more compact Driver Express VI o Driver Express V This
57. the availability of other controls will change accordingly e g read write access RepCaps Input data type Right click context menu allows for opening closing all elements focusing on item copying of attribute details to the text clipboard and defining the content up to 6 col umns from following attribute values Descriptive name Identifier Identifier without prefix Raw Command Raw Command without portions Data Type Access RepCap Definition R W Callbacks Models and Options Hi level Functions Range Help Command Range Reference Clicking on the column header allows the ascending descending sorting by that parameter Sorted column is displayed in bold font with ascending or descending symbol at the beginning Sorting works best with flatten structure of the attributes tree 3 Flatten the Attribute tree If checked all Select Attribute control nodes are removed and the entire content is shown as a list 4 Filter If ON only the attributes fulfilling the Filter criteria defined in 7c and Main Nodes defined in 7d will be visible 5 Find All If ON only the attributes fulfilling the Find criteria defined in 7b will be visible You can combine Filter and Find criteria to perform logical AND opera tion between them 7a 7h Refer to chapter 5 3 2 7a 7f tab control tabs on page 28 Driver Express VI E SS e 8 Attribute operation Refer to chapter 5 3 1 8 Attribute operation control on page 2
58. tically done with every change of attribute by checking Auto Help update checkbox 5 3 1 8 Attribute operation control Attribute operation defines what is to be done with the selected attribute In principle there are only 2 options Read or Write Other operations are derived from those two Attribute operation also affects the Express VI instance icon Note for Express VI icon By default all Hi level functions in the driver have the icon of Standard Write without the blue arrow Common features of Express VI icon Standard operations have a blue strip on Icon top Fast operations have red orange strips A small pink arrow on the left signals that you can connect the Direct cmd in string that will be placed before composed string EA Fig 5 7 Standard Write and Fast Write icons If Error Checking is ON icon has a bubble with E in left bottom corner OPC syn chronisation is shown as a small red vertical strip on the right edge WAI synchronisa tion is signaled as a longer blue vertical strip on the right edge Fig 5 8 Fast Write icons with Error Checking with OPC synchronisation with WAI synchronisa tion Listed below are all possible attribute operations with their icons Stated in brackets are the names of Operation variable used in VI Title composing see chapter 5 3 2 1 7a Title composer tab on page 28 Read Get Standard driver read method All Read functions in driver are pro grammed usin
59. tion of the terminal on the VI pattern can be also selected Variable RepCap Terminal s on VI to z ew Vi a On Fi ir D Variable RepCap Rings with Dig Displ Conditional Terminal Connect Attribute ID terminal Always connect Direct cmd out Use buffered instr handle 1 3 9 7 3 6 7 3 7 7 3 8 Tips when using drivers Use color differentiation and conditional terminals Attached file LabVIEW programs Example DifferentColorsForLabelsCondTerm vi If your test setup uses more than one instrument differentiate between them with dif ferent colors e g label colors of Express VIs This way you can quickly find which building block communicates with which instrument Instead of Case Structures use Conditional terminals Example of the code using FSW and SMW two Express VIs are configured not to send the commands when input values are NaN RF Frequency 2G Info About View VI as Icon Variable RepCap Terminal s on VI top SMW200 resource name Variable RepCap Rings with Dig Display presente ot ene Conditional Terminal FSW67 resource name Connect Attribute ID terminal E E Always connect Direct cmd out RF Amplitude Don t set DELS E Use buffered instr handle error in no error Sa ob Fig 7 4 Differentiation between different instruments by selecting different caption background col ors With Conditional terminals you can avoid using Case Structures Analyzer should always be in Single Swe
60. tputs a Application Note Instrument Drivers LabVIEW 1MA228 4e 20 General principle of LabVIEW Express VI constants setting default values for controls Compared to a normal VI the Express VI instance has 2 special properties itis not saved as a separate VI but directly inside a parent VI Every Express VI instance is unique therefore the more of them you have the bigger your parent VI gets itis reconfigurable by Configuration VI Configuration starts when you double click on its icon or select Context Menu gt Properties If you want to see the content of your Express VI instance you have to convert it to a standard VI by context menu item Open Front Panel However you cannot reconfigure it again and you have to save it separately as a standard VI The Source Express VI is visually distinguished from standard VI by light blue frame around it The following picture shows the example of a simple Express VI that can be configured to perform a math operation between 2 numbers On a picture below the Express VI instance is configured to give a result of A B Configuration VI can also take care of connecting the terminals to the Source Express VI connector and by doing so changing their accessibility to the user To find out more on the topic of Express VI enter Lab VIEW Express VI Development Toolkit User Guide into your search engine For the purposes of this document we will refer to the Configuration VI a
61. ute data type 132 Double Boolean String Enum lt none gt If there is a range defined for this value you see lt R gt at the end Enum types have number of items shown at the end e g 6 To obtain raw data type e g Double use DataTy peRaw DataTypeRaw Attribute data type 132 Double Boolean String Enum lt none gt Value Exact command parameter value that is sent to the instrument e g 110000000 000000000000 ValueHRform Command value that is sent to the instrument but in shortened form e g 110M ValueHRform3 In case of the Fixed input parameter the value is equal to lt ValueHRform gt otherwise it shows the input data type e g lt Double gt For Reading opera tions the value is empty string ValuelFfixed Same as Value if it cannot be changed during run time checkbox Fixed Input Parameter is checked Otherwise empty string RepCap Repeated capabilities string e g TR1 RepCapNE Repeated capabilities string if it s non empty Other wise empty string RawCmd Command directly taken from Attribute definition e g CALC MARK Marker ResultCmdNoParam Result command that is sent to the instrument with out parameter e g CALC MARK1 ResultCmd Result command that is sent to the instrument including the parameter e g CALC MARK1 OFF Application Note Instrument Drivers LabVIEW 1MA228 4e 29 Express VI Configuration panel ReadWrite Read Write access R W R W Depending on WAI and OPC syc
62. xt menu Compose will bring up the table where you can compose the RepCaps string e 11 Input value Input value for Write operations Type of the control depends on attribute Data type If range checking is defined to the selected attribute you can see the allowed range in its label In case of Read operation this value is disabled and ignored For data type Enum listbox item names depend on settings defined in 7e Enum Embedding e 12 Attribute ID Selected attribute value indicator e 13 SCPI Command indicator This indicator is showing a command that with the current settings will be sent to the instrument Black text is fixed content light blue text shows Repeated capabilities portions red text shows Repeated capabilities portions when the RepCaps string is not valid Purple portions are the parameters In case of the Read operation parameter is the questionmark e 14 QOK button This button finishes the configuration and the Express VI instance is modified according the settings In case of configuration error or conflict OK but ton is disabled Hovering over it with the mouse will bring up the error description text e 15 Cancel button Discards all the configuration changes and closes the configu ration panel Application Note Instrument Drivers LabVIEW 1MA228 4e 26 Driver Express VI a SS SS e 16 Help button Opens the rsspecan attr chm file page with the current attribute Optionally you can have this automa
63. ys on varia ble RepCaps Ring controls Conditional Terminal The input Perform T will be available allowing for conditional execution of the Express VI instance If you wire False to this input Direct cmd out will be equal to Direct cmd in Driver Express VI eee aS SS Connect Attribute ID terminal This setting has only effect for Standard Read Write operations For Fast Read Write operations the Attribute ID terminal is never connec ted because it cannot be changed during the run time Always connect Direct cmd out If you chose the Attribute operation that sends the data to instrument command or query you can still access the command through this terminal by checking this checkbox e g if you want to log the communication with your instrument Use buffered instr handle Check this only if you are using one instrument With every use of the Express VI the instrument handle is stored in its internal buffer All the subsequent Express VIs that have this checkbox set will not have the input instrument handle available and will use the buffered instrument handle The instrument handle out is always valid Input Value Terminal Placement You can decide where can the input value terminal be placed The default is Left Input Value Terminal Label This string control can use the same variables as Title compose string table 5 1 without rich text capabilities Double click to compose the settings The result name will be used as a la

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