NI-DAQ™mxHelpJanuary2008,370466L-01ThishelpfilecontainsinformationaboutusingNI-DAQmxtoprogramyourNationalInstrumentsdevice.NI-DAQmxisthesoftwareyouusetocommunicatewithandcontrolyourNIdataacquisition(DAQ)device.RefertoSupportinNI-DAQ8.7intheNI-DAQ8.7ReadmeforalistofdevicessupportedinNI-DAQmx.ThisdocumentdescribesonlyNI-DAQmx.ForinformationonTraditionalNI-DAQ(Legacy),refertotheTraditionalNI-DAQ(Legacy)UserManual.Formoreinformationaboutthishelpfile,refertothefollowingtopics:UsingHelpRelatedDocumentationImportantInformationTechnicalSupportandProfessionalServicesTocommentonNationalInstrumentsdocumentation,refertotheNationalInstrumentsWebsite.©2003–2008NationalInstrumentsCorporation.Allrightsreserved.

RelatedDocumentationManymanualsalsoareavailableasPDFs.YoumusthaveAdobeAcrobatReaderwithSearchandAccessibility5.0.5orlaterinstalledtoviewthePDFs.RefertotheAdobeSystemsIncorporatedWebsitetodownloadAcrobatReader.RefertotheNationalInstrumentsProductManualsLibraryforupdateddocumentationresources.Thefollowingdocumentscontaininformationthatyoumayfindhelpfulasyouusethishelpfile.Foradditionaldetailsonthesedocuments,alongwiththeirdefaultinstallationlocations,refertoni.com/kb.

DAQAssistantHelpDAQGettingStartedGuideGettingStartedwithLabVIEWGettingStartedwithLabVIEWSignalExpressLabVIEWHelpLabVIEWReal-TimeUserManualLabVIEWSignalExpressHelpLabWindows™/CVI™HelpMeasurement&AutomationExplorerHelpforNI-DAQmxNIMeasurementStudioHelpNI-DAQmxCReferenceHelpNI-DAQmxDataAcquisitionVIsSCXIQuickStartGuidePIDControlToolsetManualTakinganNI-DAQmxMeasurementinLabVIEWTakinganNI-DAQmxMeasurementinLabVIEWSignalExpressTakinganNI-DAQmxMeasurementinLabWindows/CVIUsingNI-DAQmxwithLabVIEWProjectDeviceDocumentation

ForadescriptionsofNI-DAQmxdocumentsalongwithdefaultinstallationlocations,refertoNI-DAQmxforWindowsDocumentationonni.com.

UsingHelpConventionsNavigatingHelpSearchingHelpPrintingHelpFileTopics

ConventionsThishelpfileusesthefollowingformattingandtypographicalconventions:

<> Anglebracketsthatcontainnumbersseparatedbyanellipsisrepresentarangeofvaluesassociatedwithabitorsignalname—forexample,AO<0..3>.

» The»symbolleadsyouthroughnestedmenuitemsanddialogboxoptionstoafinalaction.ThesequenceFile»PageSetup»OptionsdirectsyoutopulldowntheFilemenu,selectthePageSetupitem,andselectOptionsfromthelastdialogbox.Thisicondenotesatip,whichalertsyoutoadvisoryinformation.Thisicondenotesanote,whichalertsyoutoimportantinformation.

attribute/property ThistermisusedtorepresentpropertiesforLabVIEW,VisualC++,VisualBasic.NET,andVisualC#;andGetandSetAttributefunctionsforANSICandLabWindows™/CVI™.

bold Boldtextdenotesitemsthatyoumustselectorclickoninthesoftware,suchasmenuitemsanddialogboxoptions.Boldtextalsodenotesparameternames,emphasis,oranintroductiontoakeyconcept.

green Underlinedtextinthiscolordenotesalinktoahelptopic,helpfile,orWebaddress.

italic Italictextdenotesvariables,emphasis,crossreferences,oranintroductiontoakeyconcept.Italictextalsodenotestextthatisaplaceholderforawordorvaluethatyoumustsupply.

function/VI Thistermisusedtogenericallyrepresentfunctions,VIs,andmethods,dependingontheprogramminglanguageyouuse.Afunction/VImightnotexactlymatchthetermusedinyourprogramminglanguage.Consulttheappropriatereferencedocumentation,

suchastheNI-DAQmxCReferenceHelp,forthespecificterms.

monospace Textinthisfontdenotestextorcharactersthatyoushouldenterfromthekeyboard,sectionsofcode,programmingexamples,andsyntaxexamples.Thisfontisalsousedforthepropernamesofdiskdrives,paths,directories,programs,subprograms,subroutines,devicenames,functions,operations,variables,filenames,andextensions.

NavigatingHelp(WindowsOnly)Tonavigatethishelpfile,usetheContents,Index,andSearchtabstotheleftofthiswindoworusethefollowingtoolbarbuttonslocatedabovethetabs:

Hide—Hidesthenavigationpanefromview.Locate—LocatesthecurrentlydisplayedtopicintheContentstab,allowingyoutoviewrelatedtopics.Back—Displaysthepreviouslyviewedtopic.Forward—DisplaysthetopicyouviewedbeforeclickingtheBackbutton.Options—Displaysalistofcommandsandviewingoptionsforthehelpfile.

SearchingHelp(WindowsOnly)UsetheSearchtabtotheleftofthiswindowtolocatecontentinthishelpfile.Ifyouwanttosearchforwordsinacertainorder,suchas"relateddocumentation,"addquotationmarksaroundthesearchwordsasshownintheexample.SearchingfortermsontheSearchtaballowsyoutoquicklylocatespecificinformationandinformationintopicsthatarenotincludedontheContentstab.

WildcardsYoualsocansearchusingasterisk(*)orquestionmark(?)wildcards.Usetheasteriskwildcardtoreturntopicsthatcontainacertainstring.Forexample,asearchfor"prog*"liststopicsthatcontainthewords"program,""programmatically,""progress,"andsoon.Usethequestionmarkwildcardasasubstituteforasinglecharacterinasearchterm.Forexample,"?ext"liststopicsthatcontainthewords"next,""text,"andsoon.

NoteWildcardsdonotworkwhensearchingwithSimplifiedChinese,TraditionalChinese,Japanese,andKoreancharacters.

NestedExpressionsUsenestedexpressionstocombinesearchestofurtherrefineasearch.YoucanuseBooleanexpressionsandwildcardsinanestedexpression.Forexample,"exampleAND(programORVI)"liststopicsthatcontain"exampleprogram"or"exampleVI."Youcannotnestexpressionsmorethanfivelevels.

BooleanExpressionsClickthe buttontoaddBooleanexpressionstoasearch.ThefollowingBooleanoperatorsareavailable:

AND(default)—Returnstopicsthatcontainbothsearchterms.Youdonotneedtospecifythisoperatorunlessyouareusingnestedexpressions.OR—Returnstopicsthatcontaineitherthefirstorsecondterm.NOT—Returnstopicsthatcontainthefirsttermwithoutthesecondterm.NEAR—Returnstopicsthatcontainbothtermswithineightwordsofeachother.

SearchOptions

UsethefollowingcheckboxesontheSearchtabtocustomizeasearch:Searchpreviousresults—Narrowstheresultsfromasearchthatreturnedtoomanytopics.Youmustremovethecheckmarkfromthischeckboxtosearchalltopics.Matchsimilarwords—Broadensasearchtoreturntopicsthatcontainwordssimilartothesearchterms.Forexample,asearchfor"program"liststopicsthatincludethewords"programs,""programming,"andsoon.Searchtitlesonly—Searchesonlyinthetitlesoftopics.

PrintingHelpFileTopics(WindowsOnly)CompletethefollowingstepstoprintanentirebookfromtheContentstab:

1. Right-clickthebook.2. SelectPrintfromtheshortcutmenutodisplaythePrintTopics

dialogbox.3. SelectthePrinttheselectedheadingandallsubtopicsoption.

NoteSelectPrinttheselectedtopicifyouwanttoprintthesingletopicyouhaveselectedintheContentstab.

4. ClicktheOKbutton.

PrintingPDFDocumentsThishelpfilemaycontainlinkstoPDFdocuments.ToprintPDFdocuments,clicktheprintbuttonlocatedontheAdobeAcrobatViewertoolbar.

GettingStartedwithNI-DAQmxThissectionprovidesanoverviewofNI-DAQ,includingadiscussionofthedifferencesbetweenNI-DAQmxandTraditionalNI-DAQ(Legacy).ItalsoincludesinformationonconfiguringtasksandpointersonhowtocreateNI-DAQmxapplicationsindifferentADEs,suchasLabWindows/CVIandLabVIEW.

NI-DAQ8.xOverviewNationalInstrumentsmeasurementdevicesarepackagedwithNI-DAQdriversoftware,anextensivelibraryoffunctionsandVIsyoucancallfromyourapplicationsoftware,suchasLabVIEWorLabWindows/CVI,toprogramyourNImeasurementdevices.MeasurementdevicesincludeDAQdevicessuchastheMSeriesmultifunctionI/O(MIO)devices,signalconditioningmodules,andswitchmodules.Driversoftwarehasanapplicationprogramminginterface(API),whichisalibraryofVIs,functions,classes,attributes,andpropertiesforcreatingapplicationsforyourdevice.NI-DAQ8.xcomeswiththelatestversionofthesoftwaredriver,whichiscalledNI-DAQmx.NI-DAQmxreplacesTraditionalNI-DAQ(Legacy).NI-DAQmxandTraditionalNI-DAQ(Legacy)havetheirownAPIs,hardwareconfigurations,andsoftwareconfigurations.NI-DAQmxCDsalsoincludeLabVIEWSignalExpressLE,aneasy-to-useconfiguration-basedtoolspecificallydesignedfordataloggingapplications.

NI-DAQmxNI-DAQmxhasthefollowingadvantagesoverTraditionalNI-DAQ(Legacy):

DAQAssistant—agraphicalwaytoconfigurevirtualchannelsandmeasurementtasksforyourdevice,andtogenerateNI-DAQmxcodebasedonyourvirtualchannelsandtasks,foruseinLabVIEW,LabVIEWSignalExpress,LabWindows/CVI,andMeasurementStudio.Increasedperformance,includingfastersingle-pointanalogI/Oandmultithreading.NI-DAQmxsimulateddevicesfortestingandmodifyingapplicationswithoutplugginginhardware.Simpler,moreintuitiveAPIsforcreatingDAQapplicationsusingfewerfunctionsandVIsthanearlierversionsofNI-DAQ.ExpandedfunctionalityforLabVIEW,includingpropertynodesandwaveformdatatypesupport.SimilarAPIsandfunctionalityforANSIC,LabWindows/CVI,andMeasurementStudio,includingnative.NETandC++interfaces.ImprovedsupportandperformancefortheLabVIEWReal-TimeModule.

TraditionalNI-DAQ(Legacy)TraditionalNI-DAQ(Legacy)isanupgradeoftheearlierversionofNI-DAQ.TraditionalNI-DAQ(Legacy)hasthesameVIsandfunctionsandworksthesamewayasNI-DAQ6.9.3,exceptyoucanuseTraditionalNI-DAQ(Legacy)andNI-DAQmxonthesamecomputer,andsomehardwareisnolongersupported.

WhoCanUseNI-DAQmxYoushouldinstallanduseNI-DAQmxifthefollowingsituationsapply:

YouareanewNI-DAQuser.YouareusingdevicessupportedbyNI-DAQmx;refertotheNI-DAQReadmeforalistofsupporteddevices.YouareusingWindowsVista/2000/NT/XP.

IfyouareusingNIapplicationsoftwarewithNI-DAQmx,youmustuseLabVIEW,LabWindows/CVI,orMeasurementStudioversion7.xorlater,LabVIEWSignalExpress2.xorlater(includingSignalExpressLE),ortheLabVIEWReal-TimeModule7.1orlater.IfyouuseoneoftheMicrosoft.NETlanguages,VisualC#and/orVisualBasic.NET,oradevicesupportedonlybyNI-DAQmx,suchasanMSeriesdevice,youmustuseNI-DAQmx.YoualsocanuseNI-DAQmxwithasupportedcompiler,suchasanANSICcompiler.

WhoMustUseTraditionalNI-DAQ(Legacy)InstallanduseTraditionalNI-DAQ(Legacy)ifoneofthefollowingsituationsapply:

YouhaveadevicethatisnotsupportedbyNI-DAQmx,suchastheATESeriesmultifunctionDAQdevices.YouareusingaversionofLabVIEW,LabWindows/CVI,orMeasurementStudioearlierthanversion7.0.YouareupgradingfromNI-DAQ6.9.xandhaveexistingapplicationsthatyoudonotwanttoporttoNI-DAQmxnow.NoteTheearliestversionofNIapplicationsoftwaresupportedbyTraditionalNI-DAQ(Legacy)isversion6.0.LabVIEW,LabWindows/CVI,orMeasurementStudioversions6.xcanuseTraditionalNI-DAQ(Legacy)fromtheNI-DAQ8.xdistribution.

ConfiguringaTaskDAQAssistantIntroductiontoMAXCapabilitiesofMAX

DAQAssistantTheDAQAssistantisagraphicalinterfaceforconfiguringmeasurementtasks,channels,andscales.UsingtheDAQAssistant,youcaninteractivelybuildameasurementchannelortaskforuseinLabVIEW7.xorlater,LabVIEWSignalExpress2.xorlater,LabWindows/CVI7.xorlater,andMeasurementStudio7.xorlater.WiththeseNIapplicationsoftwarepackages,youalsocanusetheDAQAssistanttogeneratecodeforuseinyourapplications.RefertotheDAQAssistantHelpforadditionalinformation.SeeAlsoCreatingChannelsandTaskswiththeDAQAssistant

IntroductiontoMeasurement&AutomationExplorer(MAX)YouconfigureyourNImeasurementandsignalconditioningdeviceswithMAX.MAXinformsotherprogramswhichdevicesyouhaveinyoursystemandhowtheyareconfigured.UseMAXtoadd,configure,test,andremoveameasurementdeviceorsignalconditioningdevice.TocheckthesystemresourcesusedbyaDAQdeviceandtoselectattachedaccessories,expandDevicesandInterfacesintheconfigurationtree,andright-clickthedeviceforoptions.Formoreinformation,refertoMeasurement&AutomationExplorerHelpforNI-DAQmx.

CapabilitiesofMAXforNI-DAQmxYoucanuseMAXforthefollowingmeasurementconfigurationactions:

Configuringresourcesandotherdevice-specificsettingsforDAQdevicesinyoursystemTestingtheresourcesandthefunctionalityofDAQdevicesinyoursystemConfiguringchannels,scales,andtasksusingtheDAQAssistantCreatingandconfiguringNI-DAQmxsimulateddevices

WhenyourunanapplicationusingNI-DAQ,thesoftwarereadstheconfigurationtodeterminethedevicesyouconfigured.Therefore,youmustconfigureDAQdevicesfirstwithMAX.RefertoMeasurement&AutomationExplorerHelpforNI-DAQmxformoreinformationaboutconfiguringandtestingDAQdevices.

ExportingandImportingaConfigurationinMAXYoucansavevirtualchannels,tasks,devices,andtheirrelationshipsforreuseinothersystemsalsorunningMAX.Toreuseaconfiguration,youmustfirstexportachannel,task,ordeviceconfiguration.Exportingtheconfigurationcreatesan.nceconfigurationfilethatyoucanthenimportintoanothersystemwithMAX.UsingtheImportandExportfeaturesinMAX,youcancreateanNI-DAQmxsimulatedversionofaphysicaldeviceorimportanNI-DAQmxsimulateddeviceconfigurationontoaphysicaldevice.Fordetailedinstructionsonhowtoexportandimportconfigurationsfordeployment,refertoMeasurement&AutomationExplorerHelpforNI-DAQmx.

NoteWhenyouuseLabWindows/CVItocreateadistribution,youcanspecifytoinvoketheMAXConfigurationExportWizardtoincludethehardwareconfigurationsinyourdeployedapplication.

Youcanalsoprogrammaticallyimportandexportconfigurationfiles.Formoreinformation,refertotheMAXConfigurationVIReferenceforLabVIEWortheMAXConfigurationFunctionReferenceforLabWindows/CVI.

DistributedApplicationsYoucanusetheDAQmxI/OServertobindtoaglobalvirtualchannelcreatedinMAXortoaDAQchannelcreatedinLabVIEWProject.YoucanusethenetworkvariableinLabVIEWProjecttobindtothechannel,oryoucanuseathird-partyOPC.RefertotheNI-DAQmxtopicsintheLabVIEWdocumentationforinstructionsonbindingtoaDAQchannelusingLabVIEWProject.

GettingStartedinyourADELabVIEWLabVIEWSignalExpressLabWindows/CVIMeasurementStudio.NETwithoutMeasurementStudioANSICwithoutLabWindows/CVI

CreatinganApplicationwithLabVIEWIfyouprogramyourNI-DAQmx-supporteddeviceinLabVIEW,youcaninteractivelycreatevirtualchannels—bothglobalandlocal—andtasksbylaunchingtheDAQAssistantfromMAXorfromwithinLabVIEW.RefertotheDAQAssistantHelpforadditionalinformation.Youalsocancreatelocalvirtualchannelsandtasks,andwriteyourownapplicationsusingtheNI-DAQmxAPI.TogetstartedinLabVIEW,followthesegeneralsteps:

1. OpenanexistingornewLabVIEWVI.2. BuildyourVI,usingtheNI-DAQmxVIsandproperties.

ForhelpwithNI-DAQmxVIs,refertoLabVIEWNI-DAQmxVIReferenceHelp.ForgeneralhelpwithprogramminginLabVIEW,refertoLabVIEWHelp.

CreatinganApplicationinLabVIEWSignalExpressIfyouuseyourNI-DAQmx-supporteddeviceinLabVIEWSignalExpress,youcancreateaprojectthatincludesNI-DAQmxsteps.WithLabVIEWSignalExpress,youcanlogandanalyzedata.YoucanalsoaddglobalvirtualchannelsthatyoucreatedinMAXtoyourNI-DAQmxstepsinLabVIEWSignalExpress.RefertotheDAQAssistantHelpforadditionalinformation.TogetstartedinLabVIEWSignalExpress,followthesegeneralsteps:

1. ClickAddStepandselectAcquireSignals»AcquireDAQmx»AnalogInput»VoltagetodroptheDAQmxAcquireStep.

2. Clickthe+buttontoaddachanneltotheNI-DAQmxstep.ForhelpwithusingtheDAQAssistantwithLabVIEWSignalExpress,refertoTakinganNI-DAQmxMeasurementinLabVIEWSignalExpress.ForgeneralhelpwithprogramminginLabVIEWSignalExpress,refertoLabVIEWSignalExpressHelp.

CreatinganApplicationwithLabWindows/CVIIfyouprogramyourNI-DAQmx-supporteddeviceinLabWindows/CVI,youcaninteractivelycreateglobalorlocalvirtualchannelsandtasksbylaunchingtheDAQAssistantfromMAXorfromwithinLabWindows/CVI.YoucangeneratetheconfigurationcodebasedonyourtaskorchannelinLabWindows/CVI.RefertotheDAQAssistantHelpforadditionalinformationaboutgeneratingcode.Youalsocancreatelocalvirtualchannelsandtasks,andwriteyourownapplicationsusingtheNI-DAQmxAPI.Tocreateanapplication,followthesegeneralsteps:

1. Createanewprojectfile(.prj).2. Openanexistingornewsourcefile(.c).3. Addyoursourcefiletotheproject.4. SelectNI-DAQmxfromtheLibraryTree,andchoosethefunction

panelyouwanttouse.5. ToviewexamplesofNI-DAQmxapplicationsinLabWindows/CVI,

launchtheNIExampleFinder.6. Buildyourapplication.

ForhelpwithNI-DAQmxfunctions,refertoNI-DAQmxCFunctionReferenceHelp.ForgeneralhelpwithprogramminginLabWindows/CVI,refertoLabWindows/CVIHelp,accessiblethroughStart»AllPrograms»NationalInstruments»LabWindowsCVI»LabWindowsCVIHelp.

CreatinganApplicationinMeasurementStudiowithVisualC++,VisualC#,orVisualBasic.NETIfyouprogramyourNI-DAQmx-supporteddeviceinMeasurementStudiousingVisualC++,VisualC#,orVisualBasic.NET,youcaninteractivelycreatechannelsandtasksbylaunchingtheDAQAssistantfromMAXorfromwithinVisualStudio.NET.YoucangeneratetheconfigurationcodebasedonyourtaskorchannelinMeasurementStudio.RefertotheDAQAssistantHelpforadditionalinformationaboutgeneratingcode.Youalsocancreatechannelsandtasks,andwriteyourownapplicationsinyourADEusingtheNI-DAQmxAPI.ForhelpwithNI-DAQmxmethodsandproperties,refertotheNI-DAQmx.NETClassLibraryortheNI-DAQmxVisualC++ClassLibraryincludedintheNIMeasurementStudioHelp.ForgeneralhelpwithprogramminginMeasurementStudio,refertotheNIMeasurementStudioHelp,whichisfullyintegratedwiththeMicrosoftVisualStudio.NEThelp.ToviewthishelpfileinVisualStudio.NET,selectMeasurementStudio»NIMeasurementStudioHelp.TocreateanapplicationinVisualC++,VisualC#,orVisualBasic.NET,followthesegeneralsteps:

1. InVisualStudio.NET,selectFile»New»ProjecttolaunchtheNewProjectdialogbox.

2. FindtheMeasurementStudiofolderforthelanguageyouwanttocreateaprogramin.

3. Chooseaprojecttype.YouaddDAQtasksasapartofthisstep.

Creatinga.NETApplicationwithoutMeasurementStudioWiththeMicrosoft.NETFrameworkversion1.1orlater,youcanuseNI-DAQmxtocreateapplicationsusingVisualC#andVisualBasic.NETwithoutMeasurementStudio.YouneedMicrosoftVisualStudio.NET2003orMicrosoftVisualStudio2005fortheAPIdocumentationtobeinstalled.TheinstalleddocumentationcontainstheNI-DAQmxAPIoverview,measurementtasksandconcepts,andfunctionreference.ThishelpisfullyintegratedintotheVisualStudio.NETdocumentation.ToviewtheNI-DAQmx.NETdocumentation,gotoStart»AllPrograms»NationalInstruments»NI-DAQ»NI-DAQmx.NETReferenceHelp.ExpandNIMeasurementStudioHelp»NIMeasurementStudio.NETClassLibrary»Referencetoviewthefunctionreference.ExpandNIMeasurementStudioHelp»NIMeasurementStudio.NETClassLibrary»UsingtheMeasurementStudio.NETClassLibrariestoviewconceptualtopicsforusingNI-DAQmxwithVisualC#andVisualBasic.NET.TogettothesamehelptopicsfromwithinVisualStudio,gotoHelp»Contents.SelectMeasurementStudiofromtheFilteredBydrop-downlistandfollowthepreviousinstructions.

CreatinganANSICApplicationwithoutLabWindows/CVINI-DAQmxhasaCAPIthatyoucanusetocreateapplications.Tocreateanapplication,followthesegeneralsteps:

1. Createanewproject.2. Openexistingornewsourcefiles(.c),andaddthemtothe

project.MakesureyouincludetheNI-DAQmxheaderfile,nidaqmx.h,inyoursourcecodefiles.YoucanfindthisheaderfileatNI-DAQ\DAQmxANSICDev\include.

3. AddtheNI-DAQmximportlibrary,nidaqmx.lib,totheproject.TheimportlibraryfilesarelocatedunderNI-DAQ\DAQmxANSICDev\lib\.

4. ToviewexamplesofNI-DAQmxapplications,gototheNI-DAQ\Examples\DAQmxANSICdirectory.

5. Buildyourapplication.ForhelpwithNI-DAQmxfunctions,refertotheNI-DAQmxCReferenceHelp,whichisinstalledbydefaultatStart»AllPrograms»NationalInstruments»NI-DAQ»NI-DAQmxCReferenceHelp.

ExamplesEachAPIincludesacollectionofprogrammingexamplestohelpyougetstarteddevelopinganapplication.Youcanmodifyexamplecodeandsaveitinanapplication.Youcanuseexamplestodevelopanewapplicationoraddexamplecodetoanexistingapplication.Torunexampleswithouthardwareinstalled,youcanuseanNI-DAQmxsimulateddevice.InMAX,refertotheMeasurement&AutomationExplorerHelpforNI-DAQmxbyselectingHelp»HelpTopics»NI-DAQmxforinformationonNI-DAQmxsimulateddevices.Tofindthelocationsofexamplesforyoursoftwareapplication,refertothefollowingtable.

SoftwareApplication ExampleLocationLabVIEWorLabWindows/CVI Help»FindExamplesLabVIEWSignalExpress ProgramFiles\National

Instruments\SignalExpress\ExamplesANSIC *...NI-DAQ\Examples\DAQmxANSICMFC7.0C++ *...NI-DAQ\Examples\MStudioVC2003VisualBasic.NETandC#forVisualStudio2003

*...NI-DAQ\Examples\DotNET1.1

MFC8.0C++ *...NI-DAQ\Examples\MStudioVC2005VisualBasic.NETandC#forVisualStudio2005

*...NI-DAQ\Examples\DotNET2.0

*ForWindowsXP,thedefaultpathis<drive>:\DocumentsandSettings\AllUsers\Documents\NationalInstruments\NI-DAQ\Examples\....ForWindowsVista,thedefaultpathis<drive>:\Users\Public\Documents\NationalInstruments\NI-DAQ\Examples\....

NoteVisualStudio2003andVisualStudio2005donotrequireMeasurementStudio.

TroubleshootingInstallationandConfigurationRefertotheDAQGettingStartedGuideandtheSCXIQuickStartGuideforgeneralinstallationandconfigurationinstructions.UsethefollowingresourcesifyouhaveproblemsinstallingyourDAQhardwareand/orsoftware:

Fortroubleshootinginstructions,refertotheHardwareInstallation/ConfigurationTroubleshooteratni.com/support/install.Refertoni.com/kbfordocumentsontroubleshootingcommoninstallationandprogrammingproblemsandforansweringfrequentlyaskedquestionsaboutNIproducts.IfyouthinkyouhavedamagedyourdeviceandneedtoreturnyourNationalInstrumentshardwareforrepairorcalibration,refertoni.com/supportandsearchonSendingaBoardforRepairorCalibrationtolearnhowtobegintheReturnMerchandiseAuthorization(RMA)process.

ForLabWindows/CVIusers,iftheDataAcquisitionfunctionpanelisdisabled,youmayneedtouninstallNI-DAQandreinstallit,makingsurethatyouaddsupportforLabWindows/CVI.IfyouhaveinstalledLabWindows/CVIsupportandDataAcquisitionisstilldimmed,selectLibrary»Customize.IntheCustomizeLibraryMenudialogbox,checkDataAcquisition,andrestartLabWindows/CVI.Youmightalsoneedtoverifythatthedataacq.libisinthebindirectory.

ProgrammingTohelpyougetstartedprogramming,youcanusetheshippingexamplesforyourADE.YoucanalsovisitNI'sextensivelibraryoftechnicalsupportresourcesatni.com/support.YoucaninteractivelyconfigureglobalvirtualchannelsandtaskswiththeDAQAssistant.ForNIapplicationsoftwaresuchasLabVIEW,youcanusetheDAQAssistanttogeneratecode.Finally,theNI-DAQmxHelpcontainsprogrammingflowchartsforcommonapplicationssuchasmeasuringtemperature,current,strain,position,andacceleration.

ExternalConnectionsInadditiontotheinformationonmakingsignalconnectionsinthishelpfile,theConnectionDiagramtabintheDAQAssistantwithinMAXshowsyouhowtoconnectsignals.

CalibrationForinformationonexternallycalibratingyourdevice,includingstep-by-stepcalibrationprocedures,refertoni.com/calibration.Foranoverviewofcalibration,includingthedifferencebetweenself-calibrationandexternalcalibration,refertoCalibration.Fordevice-specificinformationrequiredforcalibrationwithNI-DAQmx,refertoDevice-SpecificCalibration.Forinformationonchannelcalibration,refertoWhatIsChannelCalibration?

CPUUsageNI-DAQmxtasksuse100%oftheCPUifnootherprocessesarerunning.However,assoonasanotherprocessrequirestheCPU,theNI-DAQmxtaskyieldstothatprocess.

TroubleshootinganSCXISystemThefollowingaresometipstohelpyoutroubleshootproblemswithanSCXIsystem:

CanMAXestablishcommunicationwiththechassis?Ifnot,tryoneorallofthefollowing:ConnecttheDAQdevicetoadifferentmoduleinthechassis.Tryadifferentcableassembly.Tryadifferentchassis.TryadifferentDAQdevice.Ifyouhavemultiplechassis,disconnectthemandreconnectthemoneatatimetoisolatetheproblem.MakesurethateachSCXIchassisconnectedtoasingleDAQdevicehasauniqueaddress.IfyouhavemultipleSCXImodules,removeallthemodulesandtesteachmoduleindividually.Ifaparticularchassisdoesnotwork,tryanotherone.Ifyouaregettingerroneousreadingsfromyoursignalsource,disconnectthesignalsourceandshorttheinputchanneltoground.Youshouldgeta0Vreading.Alternately,connectabatteryorotherknownsignalsourcetotheinputchannel.Runanexampleprogramtoseeifyoustillgeterroneousresults.

FrequentlyAskedQuestions(FAQ)Foranswerstofrequentlyaskedquestions,visittheNI-DAQmxFAQ.

GenericProgrammingFlowchartsThissectioncontainsgeneralprogrammingflowchartsthatyoucanusewhencreatinganapplication.Youalsocanfindprogrammingflowchartsfortypicalapplications—suchasmeasuringtemperature,measuringcurrent,andmeasuringstrain—intheCommonApplicationssectionofthishelpfile.Intheprogrammingflowcharts,manyapplicationsalsoincludeexplicitcontrolfunctionstostart,stop,andclearthetask.Forinstance,forapplicationsthatuseyourcounter/timer,suchasfinitecounterinput,youneedtocalltheStartfunction/VItoarmthecounter.InLabVIEW,clearingoccursautomatically.ForotherADEs,youmustincludethesefunctionsinyourapplication.FunctionsandVIsproducethecorefunctionalityoftheNI-DAQmxAPI.Forinstance,NI-DAQmxincludesfunctionsfortiming,triggering,reading,andwritingsamples.However,foradvancedfunctionality,VisualC++,VisualC#,VisualBasic.NET,andLabVIEWrequireproperties.ANSICandLabWindows/CVIemploytheGetandSetAttributefunctions.Formoreinformation,refertotheprogrammingreferencehelpforyourADE.

AnalogInputProgrammingFlowchartsSingleSampleAnalogInputFiniteAnalogInputContinuousAnalogInput

AnalogOutputProgrammingFlowchartsSingleSampleAnalogOutputFiniteAnalogOutputContinuousAnalogOutput

DigitalInputProgrammingFlowchartsSingleSampleDigitalInputFiniteDigitalInputContinuousDigitalInput

DigitalOutputProgrammingFlowchartsSingleSampleDigitalOutputFiniteDigitalOutputContinuousDigitalOutput

MeasuringCounterValues(CounterInput)ProgrammingFlowchartsSinglePointCounterInputFiniteCounterInputContinuousCounterInput

AnalogInputProgrammingFlowchartsThissectioncontainsgeneralprogrammingflowchartsthatyoucanusewhencreatinganapplication.Youalsocanfindprogrammingflowchartsfortypicalapplications—suchasmeasuringtemperature,measuringcurrent,andmeasuringstrain—intheCommonApplicationssectionofthishelpfile.FunctionsandVIsprovidethecorefunctionalityoftheNI-DAQmxAPI.Forinstance,NI-DAQmxincludesfunctionsfortiming,triggering,reading,andwritingsamples.However,foradvancedfunctionality,VisualC++,VisualC#,VisualBasic.NET,andLabVIEWrequireproperties.ANSICandLabWindows/CVIemploytheGetandSetAttributefunctions.Formoreinformation,refertotheprogrammingreferencehelpforyourADE.

AnalogInputProgrammingFlowchartsSingleSampleAnalogInputFiniteAnalogInputContinuousAnalogInputTriggeredAcquisition

SingleSampleAnalogInputProgrammingFlowchartAcquiringasinglesampleisanon-demandoperation.Inotherwords,NI-DAQmxacquiresonevaluefromaninputchannelandimmediatelyreturnsthevalue.Thisoperationdoesnotrequireanybufferingorhardwaretiming.Forexample,ifyouperiodicallyneededtomonitorthefluidlevelinatank,youacquiresingledatapoints.Youcanconnectthetransducerthatproducesavoltagerepresentingthefluidleveltoasinglechannelonyourmeasurementdeviceandinitiateasingle-channel,single-pointacquisitionwhenyouwanttoknowthefluidlevel.WithNI-DAQmx,youalsocangatherdatafrommultiplechannels.Forinstance,youmightwanttomonitorthefluidlevelinthetankaswellasthetemperature.Inthiscase,youneedtwotransducersconnectedtotwochannelsonyourdevice.Thefollowingflowchartdepictsthestepstoprogrammaticallycreateasinglesampleanaloginputapplication.Ifyouprefer,youcanconfigureataskforacquiringasinglesampleusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesareread,includetheStartfunction/VIandStopfunction/VIinyourapplication.Inthepreviousflowchart,theStartfunction/VIwouldcomejustbeforeyoureadsamples,andStopwouldcomejustbeforeyouclearthetask.

FiniteAnalogInputProgrammingFlowchartOnewaytoacquiremultiplesamplesforoneormorechannelsistoacquiresinglesamplesinarepetitivemanner.However,acquiringasinglesampleononeormorechannelsoverandoverisinefficientandtimeconsuming.Moreover,youdonothaveaccuratecontroloverthetimebetweeneachsampleorchannel.Instead,youcanusehardwaretiming,whichusesabufferincomputermemorytoacquiredatamoreefficiently.Programmatically,youneedtoincludethetimingfunction,specifyingthesamplerateandthesamplemode(finite).Aswithotherfunctions,youcanacquiremultiplesamplesforasinglechannelormultiplechannels.YoucanconfigureataskforfiniteanaloginputusingtheDAQAssistant.

ContinuousAnalogInputProgrammingFlowchartIfyouwanttoview,process,orlogasubsetofthesamplesastheyarebeingacquired,youneedtocontinuallyacquiresamples.Forthesetypesofapplications,setthesamplemodetocontinuous.ThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationformeasuringvoltage.Instead,youcanconfigureataskforcontinuousanaloginputusingtheDAQAssistant.

AnalogOutputProgrammingFlowchartsThissectioncontainsgeneralprogrammingflowchartsthatyoucanusewhencreatinganapplication.Youalsocanfindprogrammingflowchartsfortypicalapplications—suchasgeneratingvoltageandgeneratingcurrent—intheCommonApplicationssectionofthishelpfile.Intheprogrammingflowcharts,manyapplicationsalsoincludeexplicitcontrolfunctionstostart,stop,andclearthetask.InLabVIEW,clearingoccursautomatically.ForotherADEs,youmustincludethesefunctionsinyourapplication.FunctionsandVIsprovidethecorefunctionalityoftheNI-DAQmxAPI.Forinstance,NI-DAQmxincludesfunctionsfortiming,triggering,reading,andwritingsamples.However,foradvancedfunctionality,VisualC++,VisualC#,VisualBasic.NET,andLabVIEWrequireproperties.ANSICandLabWindows/CVIemploytheGetandSetAttributefunctions.Formoreinformation,refertotheprogrammingreferencehelpforyourADE.

AnalogOutputProgrammingFlowchartsSingleSampleAnalogOutputFiniteAnalogOutputContinuousAnalogOutput

SingleSampleAnalogOutputProgrammingFlowchartGeneratingasinglesampleisanon-demandoperation.Inotherwords,NI-DAQmxgeneratesonevaluefromaninputchannelandimmediatelyreturnsthevalue.Thisoperationdoesnotrequireanybufferingorhardwaretiming.WithNI-DAQmx,youalsocangeneratesamplesfrommultiplechannels.Ifyouprefer,youcanconfigureataskforgeneratingasinglesampleusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesarewritten,includetheStartfunction/VIandStopfunction/VIinyourapplication.Intheprecedingflowchart,theStartfunction/VIwouldcomejustbeforeyouwritesamples,andStopwouldcomejustbeforeyouclearthetask.

FiniteAnalogOutputProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtogenerateafinitenumberofvoltagesamplesinabufferedgeneration.Ifyouprefer,youcanconfigurethistaskusingtheDAQAssistant.

ContinuousAnalogOutputProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtocontinuouslygeneratevoltagesamples.Ifyouprefer,youcanconfigurethistaskusingtheDAQAssistant.

CounterProgrammingFlowchartsThissectioncontainsgeneralprogrammingflowchartsthatyoucanusewhencreatinganapplication.Youalsocanfindprogrammingflowchartsfortypicalapplications—suchascountingedgesandgeneratingpulses—intheCommonApplicationssectionofthishelpfile.Intheprogrammingflowcharts,manyapplicationsalsoincludeexplicitcontrolfunctionstostart,stop,andclearthetask.Forinstance,forapplicationsthatuseyourcounter,suchascountingedgesormeasuringperiod,youneedtocalltheStartfunction/VItoarmthecounter.InLabVIEW,clearingoccursautomatically.ForotherADEs,youmustincludethesefunctionsinyourapplication.FunctionsandVIsprovidethecorefunctionalityoftheNI-DAQmxAPI.Forinstance,NI-DAQmxincludesfunctionsfortiming,triggering,reading,andwritingsamples.However,foradvancedfunctionality,VisualC++,VisualC#,VisualBasic.NET,andLabVIEWrequireproperties.ANSICandLabWindows/CVIemploytheGetandSetAttributefunctions.Formoreinformation,refertotheprogrammingreferencehelpforyourADE.

CounterInputProgrammingFlowchartsSinglePointCounterInputFiniteCounterInputContinuousCounterInput

SinglePointCounterInputProgrammingFlowchartThefollowingflowchartdepictsthemainstepsyoumustcompleteforanon-demandcountingapplication.Ifyouprefer,youcanconfigurethistaskusingtheDAQAssistant.

FiniteCounterInputProgrammingFlowchartThefollowingflowchartdepictsthemainstepsyoumustcompleteforfinitecounterinputinanNI-DAQmxapplication.Ifyouprefer,youcanconfigurethistaskusingtheDAQAssistant.

1Time-basedmeasurementsincludeperiod,semi-period,pulsewidth,two-edgeseparation,anddigitalfrequency.2Edgecounting-basedmeasurementsincludeedgecounting,encoder-basedpositionmeasurements,andGPStimestampmeasurements.

ContinuousCounterInputProgrammingFlowchartThefollowingflowchartdepictsthemainstepsyoumustcompleteforcontinuouscountinginanNI-DAQmxapplication.Ifyouprefer,youcanconfigurethistaskusingtheDAQAssistant.

1Time-basedmeasurementsincludeperiod,semi-period,pulsewidth,two-edgeseparation,anddigitalfrequency.2Edgecounting-basedmeasurementsincludeedgecounting,encoder-basedpositionmeasurements,andGPStimestampmeasurements.

DigitalInputProgrammingFlowchartsThissectioncontainsgeneralprogrammingflowchartsthatyoucanusewhencreatinganapplication.Youalsocanfindprogrammingflowchartsfortypicalapplications—suchasmeasuringadigitalvalue—intheCommonApplicationssectionofthishelpfile.Intheprogrammingflowcharts,manyapplicationsalsoincludeexplicitcontrolfunctionstostart,stop,andclearthetask.InLabVIEW,clearingoccursautomatically.ForotherADEs,youmustincludethesefunctionsinyourapplication.FunctionsandVIsprovidethecorefunctionalityoftheNI-DAQmxAPI.Forinstance,NI-DAQmxincludesfunctionsfortiming,triggering,reading,andwritingsamples.However,foradvancedfunctionality,VisualC++,VisualC#,VisualBasic.NET,andLabVIEWrequireproperties.ANSICandLabWindows/CVIemploytheGetandSetAttributefunctions.Formoreinformation,refertotheprogrammingreferencehelpforyourADE.

DigitalInputProgrammingFlowchartsSingleSampleDigitalInputFiniteDigitalInputContinuousDigitalInput

SingleSampleDigitalInputProgrammingFlowchartAcquiringasinglesampleisanon-demandoperation.Inotherwords,NI-DAQmxacquiresonevaluefromaninputchannelandimmediatelyreturnsthevalue.Thisoperationdoesnotrequireanybufferingorhardwaretiming.Forexample,ifyouperiodicallyneededtomonitorthefluidlevelinatank,youacquiresingledatapoints.Youcanconnectthetransducerthatproducesavoltagerepresentingthefluidleveltoasinglechannelonyourmeasurementdeviceandinitiateasingle-channel,single-pointacquisitionwhenyouwanttoknowthefluidlevel.WithNI-DAQmx,youalsocangatherdatafrommultiplechannels.Forinstance,youmightwanttomonitorthefluidlevelinthetankaswellasthetemperature.Inthiscase,youneedtwotransducersconnectedtotwochannelsonyourdevice.Thefollowingflowchartdepictsthestepstoprogrammaticallycreateanapplicationtomeasuredigitalvalues.Ifyouprefer,youcanconfigureataskforacquiringasinglesampleusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesareread,includetheStartfunction/VIandStopfunction/VIinyourapplication.Inthepreviousflowchart,theStartfunction/VIwouldcomejustbeforeyoureadsamples,andStopwouldcomejustbeforeyouclearthetask.

FiniteDigitalInputProgrammingFlowchartOnewaytoacquiremultiplesamplesforoneormorechannelsistoacquiresinglesamplesinarepetitivemanner.However,acquiringasingledatasampleononeormorechannelsoverandoverisinefficientandtimeconsuming.Moreover,youdonothaveaccuratecontroloverthetimebetweeneachsampleorchannel.Instead,youcanusehardwaretiming,whichusesabufferincomputermemorytoacquiredatamoreefficiently.Programmatically,youneedtoincludethetimingfunction,specifyingthesamplerateandthesamplemode(finite).Aswithotherfunctions,youcanacquiremultiplesamplesforasinglechannelormultiplechannels.YoucanconfigureataskformeasuringdigitalvaluesusingtheDAQAssistant.

NoteTriggeringandSampleClocktimingforDigitalI/Oarenotsupportedonalldevices.

ContinuousDigitalInputProgrammingFlowchartIfyouwanttoview,process,orlogasubsetofthesamplesastheyarebeingacquired,youneedtocontinuallyacquiresamples.Forthesetypesofapplications,setthesamplemodetocontinuous.ThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationforacquiringdigitalsignals.YoucanconfigureataskforcontinuouslyacquiringdigitalvaluesusingtheDAQAssistant.

NoteSampleclocktimingforDigitalI/Oisnotsupportedonalldevices.

DigitalOutputProgrammingFlowchartsThissectioncontainsgeneralprogrammingflowchartsthatyoucanusewhencreatinganapplication.YoualsocanfindprogrammingflowchartsfortypicalapplicationsintheCommonApplicationssectionofthishelpfile.Intheprogrammingflowcharts,manyapplicationsalsoincludeexplicitcontrolfunctionstostart,stop,andclearthetask.Forinstance,forapplicationsthatuseyourcounter/timer,suchascountingedgesormeasuringperiod,youneedtocalltheStartfunction/VItoarmthecounter.InLabVIEW,clearingoccursautomatically.ForotherADEs,youmustincludethesefunctionsinyourapplication.FunctionsandVIsprovidethecorefunctionalityoftheNI-DAQmxAPI.Forinstance,NI-DAQmxincludesfunctionsfortiming,triggering,reading,andwritingsamples.However,foradvancedfunctionality,VisualC++,VisualC#,VisualBasic.NET,andLabVIEWrequireproperties.ANSICandLabWindows/CVIemploytheGetandSetAttributefunctions.Formoreinformation,refertotheprogrammingreferencehelpforyourADE.

DigitalOutputProgrammingFlowchartsSingleSampleDigitalOutputFiniteDigitalOutputContinuousDigitalOutput

SingleSampleDigitalOutputProgrammingFlowchartGeneratingasinglesampleisanon-demandoperation.Inotherwords,NI-DAQmxgeneratesonevalueonanoutputchannelimmediatelyaftertheWritefunction/VIiscalled.Thisoperationdoesnotrequireanybufferingorhardwaretiming.WithNI-DAQmx,youalsocangeneratesamplesfrommultiplechannels.Ifyouprefer,youcanconfigureataskforgeneratingasinglesampleusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesarewritten,includetheStartfunction/VIandStopfunction/VIinyourapplication.Intheprecedingflowchart,theStartfunction/VIwouldcomejustbeforeyouwritesamples,andStopwouldcomejustbeforeyouclearthetask.

FiniteDigitalOutputProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtogenerateafinitenumberofdigitalvaluesinabufferedgeneration.Ifyouprefer,youcanconfigureataskforgeneratingdigitalvaluesusingtheDAQAssistant.

NoteSampleclocktimingforDigitalI/Oisnotsupportedonalldevices.

ContinuousDigitalOutputProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtocontinuouslygeneratedigitalvalues.Ifyouprefer,youcanconfigureataskforgeneratingdigitalvaluesusingtheDAQAssistant.

NoteSampleclocktimingforDigitalI/Oisnotsupportedonalldevices.

TriggeredAcquisitionProgrammingFlowchartThefollowingflowchartdepictsthemainstepsyoufollowforaddingtriggeringtoanacquisition.Ifyouprefer,youcanconfiguretriggeringwiththeDAQAssistant.

MeasuringTemperatureNoteTemperaturemeasurementsmayrequireyoutoconditionthesignal.Theconditioningrequirementsdependonyoursensor.RefertotheOverviewofTemperatureSensorTypesforanexplanationofsensortypesandconditioningrequirements.

UsingaThermocoupletoMeasureTemperatureApopularwaytomeasuretemperaturewithaDAQdeviceistouseathermocouple,asshowninthefollowingfigure,becausethermocouplesareinexpensive,easytouse,andeasytoobtain.Thermocouplesproduceavoltagethatvariesbasedontemperature.Usingathermocouple,youcanmeasureavoltageanduseaformulatoconvertthevoltagemeasurementtotemperature.

Thetypicalwiringforathermocouple,asshowninthefollowingfigure,usesaresistor,R,onlyifthethermocoupleisnotgroundedatanyotherpoint.If,forexample,thethermocoupletipwerealreadygrounded,usingaresistorwouldcauseagroundloopandresultinerroneousreadings.

YoualsocanmeasuretemperatureusingResistanceTemperatureDetectors(RTD)andThermistors.MakingSignalConnectionsCreatingaProgramRTDThermistorThermocouple

Examples

MeasuringTemperaturewithanRTDProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtomeasuretemperaturewithanRTD.Alternatively,youcanconfigureataskformeasuringtemperatureusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesareread,includetheStartfunction/VIandStopfunction/VIinyourapplication.Inthepreviousflowchart,theStartfunction/VIwouldcomejustbeforeyoureadsamples,andStopwouldcomejustbeforeyouclearthetask.

Measuringtemperatureisanexampleofanaloginputmeasurement.RefertoAnalogInputProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

MeasuringTemperaturewithaThermistorProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtomeasuretemperaturewithathermistor.Alternatively,youcanconfigureataskformeasuringtemperatureusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesareread,includetheStartfunction/VIandStopfunction/VIinyourapplication.Inthepreviousflowchart,theStartfunction/VIwouldcomejustbeforeyoureadsamples,andStopwouldcomejustbeforeyouclearthetask.

Measuringtemperatureisanexampleofanaloginputmeasurement.RefertoAnalogInputProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

MeasuringTemperaturewithaThermocoupleProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtomeasuretemperaturewithathermocouple.Alternatively,youcanconfigureataskformeasuringtemperatureusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesareread,includetheStartfunction/VIandStopfunction/VIinyourapplication.Inthepreviousflowchart,theStartfunction/VIwouldcomejustbeforeyoureadsamples,andStopwouldcomejustbeforeyouclearthetask.

Measuringtemperatureisanexampleofanaloginputmeasurement.RefertoAnalogInputProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

MeasuringandGeneratingCurrentManymeasurementdevicescanmeasureandgeneratecurrent.TomeasureorgeneratecurrentwithaDAQdevice,youneedaresistor.Currentthencanbemeasuredthroughananaloginputconnectororgeneratedthroughananalogoutputconnector.Theresistancemustbeplacedinparallelwiththeconnectorandthecurrentsource.Tomeasurevoltagedroppedacrosstheresistorandconvertittocurrent,useOhm'sLaw.I(A)=V(V)/R(Ω)

whereIisthecurrent,Visthevoltage,andRistheresistance.

4to20mALoops4to20milliamp(4-20mA)loopsarecommonlyusedinmeasurementsystems.4-20mAloopscoupleadynamicrangewithalivezeroof4mAforopencircuitdetectioninasystemthatdoesnotproducesparks.Otheradvantagesincludeavarietyofcompatiblehardware,alongoperatingrange,andlowcost.4-20mAloopshaveavarietyofuses,includingdigitalcommunications,controlapplications,andreadingremotesensors.Thepurposeofthe4-20mAcurrentloopisforthesensortotransmitasignalintheformofacurrent.Inthefollowingfigure,theLevelSensorandRemoteSensorElectronicsaretypicallybuiltintoasingleunit.Anexternal24VDCsupplypowersthesensor.Thesensorregulatesthecurrent,whichrepresentsthevalueofwhatthesensormeasures,inthiscase,thefluidlevelinatank.

CurrentLoopWiringTheDAQdevicereadsthevoltagedropacrossthe249ΩresistorRp,usingOhm'sLaw.Becausethecurrentis4-20mAandRpis249Ω,Vrangesfrom0.996Vto4.98V,whichiswithintherangethatDAQdevicescanread.Althoughtheequationisusefulforcalculatingthecurrent,thecurrenttypicallyrepresentsaphysicalquantityyouwanttomeasure.Inthefollowingfigure,thetanklevelmeasures0to50feet.4mArepresents0feet,and20mArepresents50feet.Listhetanklevel,andIisthecurrent.

LinearRelationshipbetweenTankLevelandCurrentUsingtheOhm'sLawequationandsubstituting0.249forthevalueofRp,youcanderiveLintermsofmeasuredvoltage:

MakingSignalConnectionsCreatingaProgramMeasuringCurrentGeneratingCurrent

ExamplesSeeAlsoTipsonMeasuringACCurrent

MeasuringCurrentProgrammingFlowchartThefollowingflowchartillustratesthemainstepsrequiredinanNI-DAQmxapplicationtomeasurecurrent.Alternatively,youcanconfigureataskformeasuringcurrentusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesareread,includetheStartfunction/VIandStopfunction/VIinyourapplication.Inthepreviousflowchart,theStartfunction/VIwouldcomejustbeforeyoureadsamples,andStopwouldcomejustbeforeyouclearthetask.

Measuringcurrentisanexampleofananaloginputmeasurement.RefertoAnalogInputProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

TipsonMeasuringACCurrentTomeasureACcurrent,insertapreciselycalibrated,low-valueresistorintothesignalpathandmeasurethevoltagedropacrosstheresistor.Youmustthenperformhigh-passfilteringontheresultingsignaltoremovetheDCcomponent.Youcanperformthisfilteringusingananalogfilterordigitalsignalprocessingtechniques,suchasthefilteringtoolsintheanalysislibraryofLabVIEW.

MeasuringStrainStrain(ε)istheamountofdeformationofabodyduetoanappliedforce.Specifically,strainisthefractionalchangeinlength,asshowninthefollowingfigure.

Straincanbepositive(tensile)ornegative(compressive).Althoughdimensionless,strainissometimesexpressedinunitssuchasin./in.ormm/mm.Inpractice,themagnitudeofmeasuredstrainisverysmall.Therefore,strainisoftenexpressedasmicrostrain(µε).Whenauniaxialforcestrainsabar,asintheprecedingfigure,aphenomenonknownasPoissonStraincausesthegirthofthebar,D,tocontractinthetransversedirection,whichisperpendiculartotheforce.ThemagnitudeofthistransversecontractionisamaterialpropertyindicatedbyitsPoisson'sRatio.ThePoisson'sRatioofamaterialisthenegativeratioofthestraininthetransversedirectiontothestrainintheaxialdirection,whichisparalleltotheforce.Poisson'sRatioforsteel,forexample,rangesfrom0.25to0.3.Tomeasurestrain,youcanuseoneormorestraingagesinaWheatstonebridgeinoneofseveralbridgeconfigurations.RefertoSignalConditioningRequirementsforStrainGagesformoreinformationaboutstraingagesandbridgeconfigurations.MakingSignalConnectionsCreatingaProgramExamples

MeasuringStrainProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtomeasurestrain.Alternatively,youcanconfigureatasktomeasurestrainwithastraingageusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesareread,includetheStartfunction/VIandStopfunction/VIinyourapplication.Inthepreviousflowchart,theStartfunction/VIwouldcomejustbeforeyoureadsamples,andStopwouldcomejustbeforeyouclearthetask.

Measuringstrainisanexampleofananaloginputmeasurement.RefertoAnalogInputProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

MeasuringResistanceResistanceistheoppositiontopassageofanelectriccurrent.OneOhm(Ω)istheresistancethroughwhichonevolt(V)ofelectricforcecausesoneampere(A)toflow.Twocommonmethodsformeasuringresistancearethe2-wiremethodandthe4-wiremethod.Bothmethodssendacurrentthrougharesistorwithameasurementdevicemeasuringthevoltagedropfromthesignalbeforeandafteritcrossestheresistor.The2-wiremethodiseasiertoimplement,butthismethodislessaccuratethanthe4-wiremethodforresistancesbelow100Ω.Tocalculateresistance,usethefollowingequation.R(Ω)=V(V)/I(A)

whereRistheresistance,Visthevoltage,andIisthecurrent.MakingSignalConnectionsCreatingaProgramExamples

MeasuringResistanceProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtomeasureresistance.Alternatively,youcanconfigureataskformeasuringresistanceusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesareread,includetheStartfunction/VIandStopfunction/VIinyourapplication.Intheprecedingflowchart,theStartfunction/VIwouldcomejustbeforeyoureadsamples,andStopwouldcomejustbeforeyouclearthetask.

Measuringresistanceisanexampleofananaloginputmeasurement.RefertoAnalogInputProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

MeasuringVoltageMostmeasurementdevicescanmeasure,orread,voltage.Twocommonvoltagemeasurementsaredirectcurrent(DC)andalternatingcurrent(AC).

MeasuringDCVoltageDCvoltageisusefulformeasuringphenomenathatchangeslowlywithtime,suchastemperature,pressure,orstrain.WithDCsignals,youwanttoaccuratelymeasuretheamplitudeofasignalatagivenpointintime.WindSpeedExampleThefollowingfigureshowsatypicalwiringdiagramforananemometerwithanoutputrangeof0to10V,whichcorrespondstowindspeedof0to200mph.Usethefollowingequationtoscalethedata:

Usingthisequation,ameasurementof3Vwouldcorrespondtoawindspeedof60mph(3V×20mph/V=60mph).Noticethatthewiringdiagraminthefollowingfigureusesaresistor,R,becauseananemometerisusuallynotagroundedsignalsource.Iftheanemometertransducerwerealreadygrounded,usingaresistorwouldcauseagroundloopandresultinerroneousreadings.

AveragingAveragingcanimprovemeasurementaccuracyfornoisyandrapidlychangingsignals.Thefollowingfigureshowswhatanactualwindspeedmightlooklikeovertime.Duetogustingwinds,thespeedvalueslooknoisy.Noticethatthewindspeedreadingof29mphisapeakspeedthatmightgivetheimpressionthatthewindisholdingat29mph.Abetterrepresentationmightbetotaketheaveragespeedoverashortperiodoftime.

Onecommonreasonforaveragingistoeliminate50or60Hzpowerlinenoise.Theoscillatingmagneticfieldaroundpowerlinescanintroducenoisevoltagesonunshieldedtransducerwiring.Becausepowerlinenoiseissinusoidal,orshapedlikeasinewave,theaverageoveroneperiodiszero.Ifyouuseascanratethatisanintegermultipleofthenoiseandaveragedataforanintegermultipleofperiods,youcaneliminatethelinenoise.Oneexamplethatworksforboth50and60Hzistosampleat300samplespersecondandaverage30points.Noticethat300isanintegermultipleofboth50and60.Oneperiodofthe50Hznoiseis300/50=6points.Oneperiodofthe60Hznoiseis300/60=5points.Averaging30pointsisanintegermultipleofbothperiods,soyoucanensurethatyouaveragewholeperiods.

MeasuringACVoltageACvoltageisawaveformthatconstantlyincreases,decreases,andreversespolarity.ACvoltageiscommoninhousehold,lab,andindustrialdevicesbecausemostpowerlinesdeliverACvoltage.YoucanmeasureACvoltagestodeterminethemaximum,minimum,andpeak-to-peakvaluesofasignal.Thepeak-to-peakvalueofasignalisthemaximumvoltageswing,frommaximumtominimum.ACVoltageandRootMeanSquare(RMS)Voltage,current,andpowerarenotconstantvaluesbecauseACsignalsalternate.However,youcanuseVrms(rootmeansquare)tomeasurevoltage,current,andpowersuchthataloadconnectedtoa120voltsAC(VAC)sourcedevelopsthesameamountofpowerasthatsameloadconnectedtoa120voltsDC(VDC)source.WithRMS,thepowerformulaforDCalsoworksforAC.Forsinusoidalwaveforms,Vrms=Vpeak/squarerootof2.BecausevoltmetersreadVrms,the120VACofatypicalU.S.walloutletactuallyhasapeakvalueofabout170V.MakingSignalConnectionsCreatingaProgramExamples

MeasuringVoltageProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtomeasurevoltage.Alternatively,youcanconfigureataskformeasuringvoltageusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesareread,includetheStartfunction/VIandStopfunction/VIinyourapplication.Inthepreviousflowchart,theStartfunction/VIwouldcomejustbeforeyoureadsamples,andStopwouldcomejustbeforeyouclearthetask.

Measuringvoltageisanexampleofananaloginputmeasurement.RefertoAnalogInputProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.TomeasureACvoltages,yougenerallyuseahardwaretimedacquisition,suchastheonesshowninFiniteVoltageMeasurementsandContinuousVoltageMeasurements.TomeasureDCvoltages,youoftendonotneedabufferorhardwaretiming,soyoucanuseasimpleapplicationsuchastheoneshowninAcquiringaSingleSample.

GeneratingVoltageYoucangeneratesinglesampleDCsignalsortime-varyingmultiplesamplesignals.

SingleSamples—IncludingSteadySignalsUsesinglesamplesifthesignallevelismoreimportantthanthegenerationrate.Forinstance,generateonesampleatatimeifyouneedtogenerateaconstant,orDC,signal.Youcanusesoftwareorhardwaretimingifthedevicesupportshardwaretimingtocontrolwhenthedevicegeneratesasignal.

Time-VaryingMultipleSamplesUsemultiplesamplesifthegenerationrateisjustasimportantasthesignallevel,asinanACsinewave.Functiongeneratorsareacommontypeofdevicethatyoucanprogramtoproducecertaintypesofwaveforms,suchassine,triangle,andsquarewaves.YoualsocanuseaDAQdeviceasafunctiongenerator.Youdothisbygeneratingonecycleofasinewave,suchaswiththeSineGenerationVIinLabVIEW,storingonecycleofsinewavedatainawaveform,andprogrammingthedevicetogeneratethevaluescontinuouslyfromthewaveformonepointatatimeataspecifiedrate.Alsocalledbufferedanalogoutput,generatingmultiplesamplesinvolvesthefollowingsteps:

1. Yourapplicationwritesmultiplesamplesintoabuffer.2. Allthesamplesinthebufferarethensenttoyourdevice

accordingtothetimingyouspecify.Youcanusesoftwareorhardwaretiming(ifyourdevicesupportshardwaretiming)tocontrolwhenyourdevicegeneratesasignal.

MakingSignalConnectionsCreatingaProgramGeneratingVoltageGeneralProgrammingFlowGeneratingMultipleSamplesProgrammingFlow

ExamplesSeeAlsoExternalReferenceSourcesforGeneratingVoltageWhatisaBuffer?

GeneratingVoltageProgrammingFlowchartThefollowingflowchartillustratesthemainstepsrequiredinanNI-DAQmxapplicationtogeneratevoltage.Alternatively,youcanconfigureataskforgeneratingvoltageusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesareread,includetheStartfunction/VIandStopfunction/VIinyourapplication.Inthepreviousflowchart,theStartfunction/VIwouldcomejustbeforeyoureadsamples,andStopwouldcomejustbeforeyouclearthetask.

Generatingvoltageisanexampleofananalogoutputmeasurement.RefertoAnalogOutputProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

MeasuringandGeneratingDigitalValuesSignalsthatarereadormeasuredarecalledinputsignals.Thosesignalsthataregeneratedarecalledoutput,orstandardoutput.SomespecializeddevicesalsosupportaWired-ORoutput.Refertothedevicedocumentationformoreinformationaboutthetypesofinputandoutputthedevicesupports.Thissectioncoverssoftware-timeddigitalinput/outputoperationsorunstrobedoperations.Thesesignalsarecontrolledbysoftwaretiming.Measuringandgeneratingdigitalvaluesareusedinanumberofapplications,includingcontrollingrelaysandmonitoringalarmstates.Generally,measuringandgeneratingdigitalvaluesisusedinlaboratorytesting,productiontesting,andindustrialprocessmonitoringandcontrol.MakingSignalConnectionsCreatingaProgramMeasuringaDigitalValueGeneratingaDigitalValue

Examples

GeneratingaDigitalValueProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtogeneratedigitalvalues.Ifyouprefer,youcanconfigureataskforgeneratingdigitalvaluesusingtheDAQAssistant.

MeasuringaDigitalValueProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtomeasuredigitalvalues.Ifyouprefer,youcanconfigureataskforacquiringdigitalvaluesusingtheDAQAssistant.

EdgeCountingEdgecountingiswhenadevicecountsrisingorfallingedgesusingacounterchannel.Youcanchoosetodoeithersinglepointorbufferedsampleclockedgecounting.Thefollowingfigureshowsanexampleofedgecountinginwhichthecounterinadevicecountsfiveedgesontheinputterminal.

Withbufferededgecounting,thedevicelatchesthenumberofedgescountedontoeachactiveedgeofthesampleclockandstoresthenumberinthebuffer.Thereisnobuilt-inclockforbufferededgecounting,soyoumustsupplyanexternalsampleclock.

InNI-DAQmx,whendoingon-demandedgecounting,youfirstarmthecounterbycallingtheStartfunction/VI.Eachsubsequentreadreturnsthenumberofedgescountedsincethecounterwasstarted.Ifyouperformmultiplereadswithoutfirststartingthecounter,thecounterimplicitlystartsandstopswitheachReadfunction/VIcall,andthenumberofcountededgesisnotcumulativebetweenreadcalls.Youalsocanpausecountingwithon-demandedgecountinginNI-DAQmxbyconfiguringapausetrigger.Toconfigureapausetrigger,usethetriggerattributes/propertiestosetthesourceterminalofthedigitaltriggeraswellasthelevelonwhichtopause.MakingSignalConnectionsCreatingaProgram

Examples

EdgeCountingProgrammingFlowchartThefollowingflowchartdepictsthemainstepsyoumustcompleteforcountingedgesinanNI-DAQmxapplication.Ifyouprefer,youcanconfigureataskforcountingedgesusingtheDAQAssistant.

Edgecountingisanexampleofacountermeasurement.RefertoCounterProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

GeneratingPulsesSomemeasurementdevicescangenerateapulsefromthecounterofthedevice.Apulseisasignalwhoseamplitudedeviatesfromzeroforashortperiodoftime.Thepulseiseitherhighorlow.Ahighpulsestartslow,pulseshigh,andreturnslow,andalowpulsestartshigh,pulseslow,andreturnshigh.

NoteYoucanuseButterworthfiltersonlyintheLabVIEWFullandProfessionalDevelopmentSystems.

Apulsetrainismorethanonepulse.Youcanuseapulseorpulsetrainasaclocksignal,agate,oratriggerforameasurementorapulsegeneration.Youcanuseasinglepulseofknowndurationtodetermineanunknownsignalfrequencyortotriggerananalogacquisition.Youcanuseapulsetrainofknownfrequencytodetermineanunknownpulsewidth.Eachpulseorpulsetrainconsistsofthreeparts:

InitialDelay—Theamountoftimetheoutputremainsattheidlestatebeforegeneratingthepulse.HighTime—Theamountoftimethepulseisatahighlevel.LowTime—Theamountoftimethepulseisatalowlevel.

Theperiodofthepulseisthesumofthehightimeandthelowtime.Thefrequencyisthereciprocaloftheperiod,1/period.Thefollowingfigureshowsthepartsofapulse.

Thefollowingfigureshowsthepartsofapulsetrain.

Beforeyougenerateapulse,youneedtodetermineifyouwanttooutputthepulseorpulsetrainintermsoffrequency,time,ornumberofticksofthecountertimebase.Forfrequency,youneedtodeterminethedutycycle.Fortime,youspecifythehightimeandthelowtime.Usethenumberofticksifyouareusingacountertimebasewithanunknownrate.Whenyouconfigureapulsegeneration,theoutputappearsatthecounteroutputterminal.Theidlestatecontrolsthepulsegenerationpolarity.Whenyousettheidlestatetolow,thepulsegenerationstartslowfortheinitialdelay,transitionstohighforthehightime,andtransitionstolowforthelowtime,asshowninthefollowingfigure.Thehightimeandlowtimerepeatforeachpulse.

Whenyousettheidlestatetohigh,thepulsegenerationstartshighfortheinitialdelay,transitionstolowforthelowtime,andtransitionstohighforthehightime,asshowninthefollowingfigure.Inbothcases,theoutputrestsattheidlestateafterthepulsegenerationcompletes.

Whengeneratingpulses,youcangenerateeitherasinglepulse,afinitepulsetrain,oracontinuouspulsetrain.Youcanupdatethehightimeand

lowtimeofacontinuouspulsetraingenerationatanytime,includingwhiletheapplicationisrunning.Thisisusefulforapplicationsthatrequirepulsewidthmodulation,suchasproportionalintegralderivative(PID)loopcontrolapplications.Bydefault,singlepulsesaregeneratedunlessyouusetheTimingfunction/VIwiththeimplicittimingtype.TheSamplesPerChannelinputtotheTimingfunction/VIdeterminesthenumberofpulsestogenerateforfinitepulsetrains.Generatingasinglepulseoracontinuouspulsetrainonlyrequirestheuseofonecounter.However,generatingfinitepulsetrainsrequirestheuseofpairedcounters.Youcanconfigureavarietyoftriggerswithpulsegenerations.AllpulsegenerationssupportStartTriggers.SinglepulsegenerationandfinitepulsetraingenerationalsosupporttheRetriggerableproperty,orattribute,forStartTriggers.TodetermineifapulseiscompleteandthehardwareisreadyforanotherStartTrigger,querythePulseDoneproperty.Continuouspulsetraingenerationsalsosupportpausetriggers.However,youcannotuseboththestartandthepausetriggeratthesametime.Youcanusethesamepropertiesthatcreatethechanneltoupdatetherateofthepulsetraingeneration.Becauseyouneedtwopropertiestospecifytherateofthepulsetrain,therateonlyupdateswhenyousetoneofthetwoproperties.Forexample,ifyouspecifythepulsegenerationintermsoffrequency,thefrequencyanddutycyclepropertiescontroltherateofthegeneration.However,therateonlyupdateswhenyousetthefrequencyproperty.Thesameistruewhenyouspecifypulsegenerationintermsoftimeorticks;thelowtimeandlowtickspropertiescontrolwhentherateupdates.Whenupdatingtherateofthepulsegeneration,acompleteperiodofthecurrentrategeneratesbeforethenewratetakeseffect.MakingSignalConnectionsCreatingaProgramGeneratingaPulseGeneratingaFinitePulseTrainGeneratingaContinuousPulseTrain

Examples

GeneratingaPulseProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtogenerateapulse.Ifyouprefer,youcanconfigureatasktogenerateapulseusingtheDAQAssistant.

GeneratingaFinitePulseTrainProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationforgeneratingafinitepulsetrain.Alternatively,youcanconfigureataskforgeneratingthepulsetrainusingtheDAQAssistant.

GeneratingaContinuousPulseTrainProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationforgeneratingacontinuouspulsetrain.Alternatively,youcanconfigureataskforgeneratingthepulsetrainusingtheDAQAssistant.

MeasuringAccelerationAccelerationisachangeinvelocitywithrespecttotime.Anaccelerometerisatransducerthatrepresentsaccelerationasavoltage.Accelerometersalsocanmeasurevibrationandshock.Accelerometerstypicallyconvertaccelerationmeasureding'stovoltage.Forexample,asensorwitharatedoutputof10mV/gshouldproduce50mVwhensubjectedto5gofacceleration.MakingSignalConnectionsCreatingaProgramExamples

MeasuringAccelerationProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtomeasureacceleration.Alternatively,youcanconfigureataskformeasuringaccelerationusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesareread,includetheStartfunction/VIandStopfunction/VIinyourapplication.Inthepreviousflowchart,theStartfunction/VIwouldcomejustbeforeyoureadsamples,andStopwouldcomejustbeforeyouclearthetask.

Measuringaccelerationisanexampleofananaloginputmeasurement.RefertoAnalogInputProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

MeasuringAngularDisplacementAngulardisplacementismovementaroundanaxis,suchastheangularmotionoftheshaftofamotor.Anangulardisplacementsensorisadevicewhoseoutputsignalrepresentstherotationoftheshaft;itcannotmeasurethephysicaldisplacementofthewholeshaft.Onetypeofsensorusedtomeasureangulardisplacementisarotaryvariabledifferentialtransformer(RVDT).Anothertypeofsensorusedtomeasureangulardisplacementisaresolver,whichisarotatingtransformerthatcanmeasure360°ofrotation.OnMSeriesdevices,CSeriesdevices,andNI-TIO-baseddevices,youcanusethecounterstoperformdisplacementmeasurementswithquadratureencoders,orangularencoders.YoucanmeasureangularpositionwithX1,X2,andX4angularencoders.Youcanchoosetodoeitherasingle-pointorabufferedsampleclockdisplacementmeasurement.Youalsocanmeasurevelocitywithangularencoders,butyouneedtouseasampleclockwithafixedfrequency.Tomeasurevelocity,usethefollowingformula:V=D/T

whereVistheaveragevelocity,Disthedistance,andTistime.ThecountermeasuresthepositionoftheencoderusingtheAandBsignals,whichareoffsetby90°.ThecounteralsosupportstheZindex,whichprovidesaprecisereferencepointandisavailableonsomeencoders.MakingSignalConnectionsCreatingaProgramRVDTProgrammingFlowchartEncoderProgrammingFlowchart

Examples

MeasuringPositionwithEncodersProgrammingFlowchartThefollowingflowchartdepictsthemainstepsyoumustcompleteformeasuringpositionwithanencoderinanNI-DAQmxapplication.Ifyouprefer,youcanconfigureataskusingtheDAQAssistant.

Measuringpositionwithanencoderisanexampleofacountermeasurement.RefertoCounterProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

MeasuringPositionwithanRVDTorLVDTProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtomeasurepositionwithanRVDTorLVDT.Alternatively,youcanconfigureataskformeasuringpositionusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesareread,includetheStartfunction/VIandStopfunction/VIinyourapplication.Inthepreviousflowchart,theStartfunction/VIwouldcomejustbeforeyoureadsamples,andStopwouldcomejustbeforeyouclearthetask.

Measuringpositionisanexampleofananaloginputmeasurement.RefertoAnalogInputProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

MeasuringLinearDisplacementLineardisplacementismovementanddirectionalongasingleaxis.Apositionorlineardisplacementsensorisadevicewhoseoutputsignalrepresentsthedistanceanobjecthastraveledfromareferencepoint.Thelinearvariabledifferentialtransformer(LVDT)isasensorthatmeasureslineardisplacement.OnMSeriesdevices,CSeriesdevices,andNI-TIO-baseddevices,youcanusethecounterstoperformdisplacementmeasurementswithtwo-pulseencoders.Linearpositioncanbemeasuredwithtwo-pulseencoders.Youcanchoosetodoeitherasinglepointorabufferedsampleclockdisplacementmeasurement.Youalsocanmeasurevelocitywithtwo-pulseencoders,butyouneedtouseasampleclockwithafixedfrequency.Tomeasurevelocity,usethefollowingformula:V=D/T

whereVistheaveragevelocity,Disthedistance,andTistime.ThecountermeasuresthepositionoftheencoderusingtheAandBsignals,whichareoffsetby90°.ThecounteralsosupportstheZindex,whichprovidesaprecisereferencepointandisavailableonsomeencoders.MakingSignalConnectionsCreatingaProgramLVDTProgrammingFlowchartEncoderProgrammingFlowchart

Examples

MeasuringAnalogFrequencySomedevicescanmeasureanalogfrequencydirectlyusingfrequency-to-voltagecircuitry.Manydevices,however,onlymeasurevoltage,andyoumustusesoftwarealgorithmstoconvertthosemeasurementstofrequency.Devicesthatmeasureanalogfrequency,suchasDSAdevicesandtheSCXI-1126,havecircuitrythatproducestriggersofthesamefrequencyasthemeasuredsignal.Everytimethesignalpassesfromthresholdlevelminushysteresistothresholdlevel,atriggeroccurs.Apulsegeneratorusesthesetriggersandproducesapulseonceeveryfrequencycycle.Theinputfrequencyrangesetsthewidthofthispulse.Astheinputfrequencyrangeincreases,thepulsewidthgrowssmaller.ThispulsetrainisthenconvertedtoaDCsignalthathasalevelproportionaltothedutycycleofthepulsetrain.Thedutycycleisthefractionofaperiodofthepulsetrainwhenthepulseisoccurring.TheDCsignalhasavoltagethatisproportionaltotheinputfrequencyandcanthereforebescaledtothatfrequencyvalue.Fordevicesthatcannotmeasurefrequencydirectly,youneedtousesoftwarealgorithms,suchastheFastFourierTransform(FFT),toconvertvoltagetofrequency.LabVIEWFullandProfessionalDevelopmentSystemscontainsadvancedanalysisVIsthathandlethesetransformations.TheLabWindows™/CVI™fulldevelopmentsystemalsocontainsadvancedanalysisfunctionstohelpyoumeasureanalogfrequency.RegardlessofwhetheryouuseexistingVIsorfunctionsorcreateyourown,youneedtosampleatleasttwiceasfastasthehighestfrequencycomponentinthesignalyouareacquiring.

AnalogFrequency,SampleRate,andtheNyquistTheoremTheNyquistTheoremstatesthatthehighestfrequencyyoucanaccuratelyrepresentishalfthesamplingrate.Forinstance,tomeasurethefrequencyofa100Hzsignal,youneedasamplingrateofatleast200S/s.Inpractice,youshouldusesamplingratesof5to10timestheexpectedfrequenciestoimproveaccuracyofmeasurements.Inadditiontosamplerate,youneedtodeterminethenumberofsamplestoacquire.Youmustsampleaminimumofthreecyclesoftheanalogsignal.Forexample,youneedtocollectatleast15samples,orpoints,ifyouuseasamplingrateof500S/stomeasurethefrequencyofa100Hzsignal.Becauseyousampleaboutfivetimesfasterthanthesignalfrequency,yousampleaboutfivepointspercycleofthesignal.Youneeddatafromthreecycles,so5pointsx3cycles=15points.Inpractice,however,youshouldacquire10ormorecyclestoimproveaccuracyofmeasurements,soyoushouldacquire50ormoresamples.Thenumberofpointsyoucollectdeterminesthenumberoffrequencybinsthatthesamplesfallinto.Thesizeofeachbinisthesamplingratedividedbythenumberofpointsyoucollect.Forexample,ifyousampleat500S/sandcollect100points,youhavebinsat5Hzintervals.TheNyquistfrequencyisthebandwidthofthesampledsignalandisequaltohalfthesamplingfrequency.FrequencycomponentsbelowtheNyquistfrequencyappearnormally.FrequencycomponentsabovetheNyquistfrequencyappearaliasedbetween0andtheNyquistfrequency.Thealiasedcomponentistheabsolutevalueofthedifferencebetweentheactualcomponentandtheclosestintegermultipleofthesamplingrate.Forexample,ifyouhaveasignalwithacomponentat800Hzandyousampleat500S/s,thatcomponentappearsaliasedat200Hzbecause|800–(2x500)|=200(Hz).Onewaytoeliminatealiasedcomponentsistouseananaloghardwarefilterbeforeyoudigitizeandanalyzethefrequencyinformation.Ifyouwanttoperformallthefilteringinsoftware,youmustfirstsampleataratefastenoughtocorrectlyrepresentthehighestfrequencycomponentthesignalcontains.Forexample,withthehighestcomponentat800Hz,theminimumsamplingrateis1,600Hz,butyoushouldsample5to10timesfasterthan800Hz.Ifthefrequencyyouwanttomeasureisaround100Hz,youcanusealowpassButterworthfilterwithacutofffrequency(fc)of

250Hztofilteroutfrequenciesabove250Hzandpassfrequenciesbelow250Hz.

NoteLabVIEWincludesButterworthfilterswiththeLabVIEWFullandProfessionalDevelopmentSystems.

MeasuringFrequencywithFilteringThefollowingfigureshowsalowpassfilter.

LowpassFilterTheIdealFilterinthefigureisoptimal.AllfrequenciesabovetheNyquistfrequencyarerejected.TheRealFilterinthefigureiswhatyoumightactuallybeabletoaccomplishwithaButterworthfilter.ThepassbandiswhereVout/Viniscloseto1.ThestopbandoccurswhereVout/Viniscloseto0.Thefrequenciesgraduallyattenuateonthetransitionregionbetween1and0.MakingSignalConnectionsCreatingaProgramExamples

MeasuringAnalogFrequencyProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtomeasureanalogfrequency.Alternatively,youcanconfigureataskformeasuringanalogfrequencyusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesareread,includetheStartfunction/VIandStopfunction/VIinyourapplication.Inthepreviousflowchart,theStartfunction/VIwouldcomejustbeforeyoureadsamples,andStopwouldcomejustbeforeyouclearthetask.

Measuringfrequencyisanexampleofanaloginputmeasurement.RefertoAnalogInputProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

HysteresiswithAnalogFrequencyMeasurementsForwaveformrepetitions,hysteresisaddsawindowbelowthethresholdlevel.Hysteresisistypicallyusedtoavoiderroneousmeasurementsduetonoiseorjitterinthesignal.ThesignalmustdropbelowthethresholdlevelminusthehysteresisbeforeNI-DAQmxrecognizesawaveformrepetitionatthethresholdlevel.

GeneratingCurrentProgrammingFlowchartThefollowingflowchartillustratesthemainstepsrequiredinanNI-DAQmxapplicationtogeneratecurrent.Alternatively,youcanconfigureataskforgeneratingcurrentusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesareread,includetheStartfunction/VIandStopfunction/VIinyourapplication.Inthepreviousflowchart,theStartfunction/VIwouldcomejustbeforeyoureadsamples,andStopwouldcomejustbeforeyouclearthetask.

Generatingcurrentisanexampleofananalogoutputmeasurement.RefertoAnalogOutputProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

ControlYoucancreateaneventresponseorcontrolloopapplicationinanyoperatingsystemsupportedbyNI-DAQmx,suchasWindows2000.However,yourapplicationcanonlybedeterministicifyouhavetheLabVIEWReal-Timemoduleanduseyourapplicationonareal-timecontroller.ThissectionassumesthatyouareusingLabVIEWwithNI-DAQmxtocreateacontrolapplication.ItdoesnotassumethatyouhavetheLabVIEWReal-Timemoduleorthereal-timecontroller.

EventResponseInacontrolapplication,aneventisthesameasanoccurrence.Thisoccurrenceleadstoanaction,oraresponse.Anexampleismonitoringthetemperatureofanengine.Whenthetemperaturerisestoohigh,theengineslowsdown.Theevent,inthiscase,wouldbethetemperaturerisingaboveapredeterminedlevel,andtheresponsewouldbetheengineslowingdown.Anotherexamplecomesfrommanufacturing.Inamanufacturingline,asystemsenseswhenapartisinfrontofastation(theevent)andtakesareadingormanipulatesthepart(theresponse).Ifthesystemdoesnotsenseandrespondtothepresenceofthatpartinasetamountoftime,themanufacturinglinecreatesdefectiveparts.Whencreatinganeventresponseapplication,makesureyouconsidertheamountoftimeneededtorespondtotheevent.Forexample,ifthedevicecontrolsthetemperatureofyourhome,thetimetoreacttoevents(changesintemperature)islesscriticalthanifthedevicecontrolsanuclearreactor.Iftheapplicationisnottimecritical,theapplicationdoesnotneedtobedeterministic,meaningthatyoudonotneedtheLabVIEWReal-TimeModuleorareal-timecontroller.Therelativepriorityofthetaskisimportantaswell.BecauseLabVIEWismulti-threaded,youcanseparatetheapplicationintotasks,eachwithitsownpriority.Bysettingpriorities,time-criticaltaskscantakeprecedenceovernon-time-criticaltasks.Thetime-criticaltaskmustperiodicallyyieldprocessorresourcestothelower-prioritytaskssotheycanexecute.Byproperlyseparatingthetime-criticaltaskfromlowerprioritytasks,youcanreduceapplicationjitter.RefertotheLabVIEWReal-TimeModuleConceptsbookintheLabVIEWHelpformoreinformationaboutassigningprioritiestotasks.CreatingaProgramExamplesSeeAlsoKeyControlConceptsSettingPrioritiesforControlApplications

ControlLoopsAcontrolapplicationmonitorsandcontrolsasystem.Theapplicationcontinuouslyloopsbyreadingsamples,processingdata,andadjustingtheoutput.YoucanuseNI-DAQmxandDAQdevicestocreateacontrolapplication.WiththeLabVIEWReal-TimeModule,youcancreatedeterministiccontrolapplications.

CreatingaControlLoopApplicationwithNI-DAQmxThefollowingblockdiagramshowsatypicaldeterministiccontrolloopapplication.First,ananalogvalueisread.Thisvaluecorrespondstotheprocessvariable.Thisvalueiscomparedtothesetpoint,whichisspecifiedintheCtrlAlgrthmVIinthediagram,andadjustedasnecessarywithinthewhileloop,possiblyusingaPIDalgorithm.Theadjustedvalueisthenwritten.Thisvaluecorrespondstotheactuatoroutput.Intheblockdiagram,thesamplingratesarethesameforanaloginputandoutput.BecausetheexampleshownassumesasingleDAQdevice,theStartTriggersynchronizestheanaloginputandanalogoutputtasks.Formultipledevices,synchronizationworksdifferently.RefertoSynchronizationformoreinformation.Noticealsothattheslavetasktheanalogoutputtaskstartsbeforetheanaloginputtask.Finally,withintheloop,theWaitforNextSampleClockVIcheckstomakesurethattheloopexecuteswithinthespecifiedsamplingrate.Ifitdoesnot,thisVIreturnsanerror.

ExamplesSeeAlsoTimingControlLoopsKeyControlConceptsSettingPrioritiesforControlApplications

MeasuringSoundPressureSoundpressureisthedynamicvariationofthestaticpressureofairandismeasuredinforceperunitarea(Pa).Theinstantaneoussoundpressureistypicallyaveragedoveracertaindurationtogivesoundpressurelevel.Soundpressurelevelisusuallyrepresentedonalogarithmicamplitudescale,whichissimilartothehumanperceptionofhearing.Typicalvaluesonthislogarithmicscaleareasoundlevelof0dB,whichistheaveragethresholdofhumanhearing,60to70dBfornormalconversation,110dBatanextremelyloudconcert,and150dBforthenoiseofarockettakeofforajetengineatcloserange.TheSoundPressureLevel(SPLorLP)indecibelsisdefinedbythefollowingequation.SPL=20log10(p/pref)wherepistheinstantaneoussoundpressureinPaandprefis20µPa,theinternationallyacceptedreferenceforsoundpressuremeasurements,whichroughlycorrespondstothethresholdofhumanhearing.Youuseamicrophonetomeasuresoundpressure.Themicrophoneactsasatransducer,creatingavoltagesignalthatisproportionaltotheinstantaneoussoundpressure.MakingSignalConnectionsCreatingaProgramExamples

MeasuringSoundPressureProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtomeasuresoundpressure.Alternatively,youcanconfigureataskformeasuringsoundpressureusingtheDAQAssistant.

TipToincreaseperformance,especiallywhenmultiplesamplesareread,includetheStartfunction/VIandStopfunction/VIinyourapplication.Inthepreviousflowchart,theStartfunction/VIwouldcomejustbeforeyoureadsamples,andStopwouldcomejustbeforeyouclearthetask.

Measuringsoundpressureisanexampleofananaloginputmeasurement.RefertoAnalogInputProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

MeasuringTime—Period,Semi-Period,PulseWidth,Two-EdgeSeparation,andDigitalFrequencyYoucanusethecountersonaDAQdevicetomeasuretime.Timemeasurementsareperiod,pulsewidth,semi-period,frequency,andtwo-edgeseparationmeasurements.

MeasuringDigitalFrequencyThedigitalfrequencyofasignalistheinverseoftheperiodofasignal.Togetthefrequencyofthesignal,taketheinverseoftheperiod.TheformulaforfrequencyisFrequency(inHz)=CounterTimebaseRate(inHz)/Count.TheCounterTimebaseRateisaknownfrequencyandisusuallyabuilt-intimesource.Ifthecountertimebaserateisunknown,youonlycanmakemeasurementsonlyintermsofticksofthecountertimebase.Thismaybethecaseifyouareusinganexternalsignalforthecountertimebase,andthefrequencyoftheexternalsignalisunknownoraperiodic.Digitalfrequencyisanexampleofatimemeasurement.RefertoConfiguringaTimeMeasurementinNI-DAQmxandTwoCounterMeasurementMethodformoreinformationaboutmeasuringtime.MakingSignalConnectionsCreatingaProgramExamples

MeasuringDigitalFrequencyandPeriodProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtomeasuredigitalfrequencyorperiod.Alternatively,youcanconfigureataskformeasuringdigitalfrequencyusingtheDAQAssistant.

Digitalfrequencyandperiodareexamplesofcountermeasurements.RefertoCounterProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

MeasuringPeriod,Semi-Period,PulseWidth,andTwo-EdgeSeparationYoucanmeasureperiod,semi-period,pulsewidth,andtwo-edgeseparationusingcounters,suchasonaDAQdevice,todeterminethedurationofaneventortodeterminetheintervaltimebetweentwoevents.Periodmeasurementsmeasurethetimebetweenconsecutiverisingorfallingedgesofapulse.Semi-periodmeasurementsmeasurethetimebetweenconsecutiveedges.Pulsewidthmeasurementsmeasurethetimebetweeneitherarisingandfallingedge,orafallingandrisingedge.Two-edgeseparationmeasurementsmeasurethetimebetweentherisingorfallingedgeofonedigitalsignalandtherisingorfallingedgeofanotherdigitalsignal.

Theformulaforperiod,semi-period,pulsewidth,andtwo-edgeseparationisasfollows:Period,Semi-Period,PulseWidth,orTwo-EdgeSeparation(inseconds)=Count/CounterTimebaseRate(inHz).whereCountisthenumberofcountertimebaseticksthatelapseduringoneperiod,semi-period,pulsewidth,ortwo-edgeseparationofthemeasuredinputsignalorsignals.TheCounterTimebaseRateisaknownfrequencyandisusuallyabuilt-intimesource.Ifthecountertimebaserateisunknown,youonlycanmakemeasurementsonlyintermsofticksofthecountertimebase.Thismaybethecaseifyouareusinganexternalsignalforthecountertimebase,andthefrequencyoftheexternalsignalisunknownoraperiodic.Period,semi-period,pulsewidth,andtwo-edgeseparationareexamples

oftimemeasurements.RefertoConfiguringaTimeMeasurementinNI-DAQmxandTwoCounterMeasurementMethodformoreinformationaboutmeasuringtime.MakingSignalConnectionsCreatingaProgramMeasuringSemi-Period,Two-EdgeSeparation,andPulseWidthProgrammingFlowchartMeasuringDigitalFrequencyandPeriodProgrammingFlowchart

Examples

MeasuringSemi-Period,Two-EdgeSeparation,andPulseWidthProgrammingFlowchartThefollowingflowchartdemonstratesthemainstepsrequiredinanNI-DAQmxapplicationtomeasuresemi-periodandpulsewidth.Alternatively,youcanconfigureataskformeasuringsemi-periodandpulsewidthusingtheDAQAssistant.

Period,semi-period,two-edgeseparation,andpulsewidthisanexampleofacountermeasurement.RefertoCounterProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

MeasuringGPSTimestampYoucantakeaGPStimestampmeasurementwiththeNIPXI-6608.InaGPStimestampmeasurement,theNIPXI-6608determinestheprecisetimeofyearusingaspecializedonboardcounter.Youcanselectasinglepoint(on-demand)timestamporabuffered(sampleclock)timestamp.YoucansynchronizetheGPStimestampcountertoaGPSreceiversignalbyusingapulsepersecond(PPS)oranIRIG-B(timecodeTTL)synchronizationsignalfromtheGPSreceiver.PPSdoesnotincludeanytiminginformation;rather,thePPSaccuratelyreportswhenthebeginningofasecondoccurs.IRIG-B,ontheotherhand,hasthetimeencodedinthesignalfromthebeginningofthecurrentyear.TheGPScountercanlatchonthecurrenttimeuponreceivingahardwaregatesignal.GPSdoesnotprovideyearinformation;however,thetimeisstoredina64-bitfloating-pointnumberthatcanbeconvertedtosecondssinceJanuary1ofthecurrentyear.Whendoinganon-demandGPStimestampmeasurement,youmustfirstarmthecounterbycallingtheStartfunction/VI.Eachsubsequentreadreturnsthenumberofsecondscounted.WhendoingabufferedGPStimestampmeasurement,thecurrenttimeislatchedoneachactiveedgeofthesampleclockandstoredinthebuffer.Thereisnobuilt-inclockforbufferedGPStimestampmeasurements,soyoumustsupplyanexternalsampleclock.MakingSignalConnectionsCreatingaProgramExamples

GPSTimestampProgrammingFlowchartThefollowingflowchartdepictsthemainstepsrequiredinanNI-DAQmxapplicationtotakeaGPStimestampmeasurementwithanNIPXI-6608.Alternatively,youcanconfigurethistaskusingtheDAQAssistant.

GPStimestampisanexampleofacountermeasurement.RefertoCounterProgrammingFlowchartsforadditionalflowchartsthatcanhelpyoucreateanapplication.

GlossaryPrefixes Numbers/Symbols A B C D E F G H I J

L M N O P R S T U V W

Symbol Prefix Valuen nano 10-9

µ micro 10-6

m milli 10-3

k kilo 103

M mega 106

Symbol Meaning% percent+ positiveof,orplus– negativeof,orminusΩ ohmº degree

Aacceleration Achangeinvelocitywithrespecttotime.accelerometer Asensorthatrepresentsaccelerationasavoltage.ADC Analog-to-digitalconverter—anelectronicdevice,often

anintegratedcircuit,thatconvertsananalogsignaltoadigitalvalue.

address Acharactercodethatidentifiesaspecificlocation(orseriesoflocations)inmemory.

ADE Applicationdevelopmentenvironment—someexamplesincludeLabVIEWandLabWindows/CVI.

advancedterminal

AterminalnotaccessiblefromtheI/Oconnectororaterminalnotcommonlyusedinmeasurementapplications.

AI Analoginput—acquisitionofdata.amplification Atypeofsignalconditioningthatimprovesaccuracyin

theresultingdigitizedsignalbyincreasingsignalamplituderelativetonoise.

analog Datarepresentedbycontinuouslyvariablephysicalquantities.

AO Analogoutput—generationofdata.angulardisplacement

Movementaboutanaxis,suchastheangularmotionoftheshaftofamotor.

angulardisplacementsensor

Adevicewhoseoutputsignalrepresentstherotationoftheshaft,suchasarotaryvariabledifferentialtransformer(RVDT).

API Applicationprogramminginterface—Alibraryoffunctions,classesorVIs,attributes,andpropertiesforcreatingapplicationsforyourdevice.

asynchronous 1. Hardware—asignalthatoccursorisacteduponatanarbitrarytime,withoutsynchronizationtoanothersignal,suchasareferenceclock.

2. Software—aVIorfunctionthatbeginsan

operationandreturnspriortothecompletionorterminationoftheoperation.

attenuation Thereductionofavoltageoracousticalpressure.Measuredreferencedtotheoriginalvoltage.

Bbandwidth Therangeoffrequenciespresentinasignal,ortherangeof

frequenciestowhichameasuringdevicecanrespond.baseaddress

Amemoryaddressthatservesasthestartingaddressforprogrammableregisters.Allotheraddressesarelocatedbyaddingtothebaseaddress.

bipolar Asignalrangethatincludesbothpositiveandnegativevalues(forexample,5Vto+5V).

BIOS BasicInput/OutputSystem—BIOSfunctionsarethefundamentallevelofanyPCorcompatiblecomputer.BIOSfunctionsembodythebasicoperationsneededforsuccessfuluseofthecomputerhardwareresources.

bit Thesmallestunitofdatausedinadigitaloperation.Bitsarebinary,sotheycanbeeithera1ora0.

buffer Insoftware,temporarystorageforacquiredorto-be-generatedsamples.

bus Thegroupofconductorsthatinterconnectindividualcircuitryinacomputer.Typically,abusistheexpansionvehicletowhichI/Oorotherdevicesareconnected.ExamplesofPCbusesaretheISAbusandPCIbus.

CCSeries Afamilyofdevicesormodulesusedforanaloginput,

analogoutput,digitalinput/output,andcounter/timerapplications.CSeriesdevicesworkwithchassisbasedontheCompactDAQ,CompactRIO,andotherarchitectures,andarecomponentsoftheNIUSB-9XXXdevices.

cDAQ TheprefixoftheproductmodelnameofaCompactDAQdevice,suchasNIcDAQ-9172.

CH Channel.channel 1. Physical—aterminalorpinatwhichyoucan

measureorgenerateananalogordigitalsignal.Asinglephysicalchannelcanincludemorethanoneterminal,asinthecaseofadifferentialanaloginputchanneloradigitalportofeightlines.Thenameusedforacounterphysicalchannelisanexceptionbecausethatphysicalchannelnameisnotthenameoftheterminalwherethecountermeasuresorgeneratesthedigitalsignal.

2. Virtual—acollectionofpropertysettingsthatcanincludeaname,aphysicalchannel,inputterminalconnections,thetypeofmeasurementorgeneration,andscalinginformation.YoucandefineNI-DAQmxvirtualchannelsoutsideatask(global)orinsideatask(local).ConfiguringvirtualchannelsisoptionalinTraditionalNI-DAQ(Legacy)andearlierversions,butisintegraltoeverymeasurementyoutakeinNI-DAQmx.InTraditionalNI-DAQ(Legacy),youconfigurevirtualchannelsinMAX.InNI-DAQmx,youcanconfigurevirtualchannelseitherinMAXorinaprogram,andyoucanconfigurechannelsaspartofataskorseparately.

3. Switch—aswitchchannelrepresentsanyconnectionpointonaswitch.Itmaybemadeup

ofoneormoresignalwires(commonlyone,two,orfour),dependingontheswitchtopology.Avirtualchannelcannotbecreatedwithaswitchchannel.SwitchchannelsmaybeusedonlyintheNI-DAQmxSwitchfunctionsandVIs.

clock Aperiodicdigitalsignal.CMRR Common-moderejectionratio—ameasureoftheability

ofaninstrumenttorejectinterferencefromacommon-modesignal,usuallyexpressedindecibels(dB).

codewidth ThesmallestdetectablechangeinaninputvoltageofaDAQdevice.

cold-junctioncompensation

Amethodofcompensatingforinaccuraciesinthermocouplecircuits.

CompactDAQ AnarchitectureorchassisforCSeriesdevices.configurationtree

ReferstotheleftwindowinMAX,whichcontainsitemssuchasDataNeighborhoodandDevicesandInterfaces.

counter/timer Acircuitthatcountsdigitaledges.Countersandtimersusuallyhavefrom16bitsto48bits(sometimesmore)countingcapability.Thetotalnumberofcountspossibleequals2N,whereNisthenumberofbitsinthecounter.Whentheedgescountedareproducedbyaclock,elapsedtimecanbecomputedfromthenumberofedgescountediftheclockfrequencyisknown.

convertclock TheclockonamultiplexeddevicethatdirectlycausesADCconversions.

customscale AmethodofinstructingNI-DAQmxtoapplyadditionalscalingtoyourdata.RefertotheCreateScalefunction/VIinyourreferencehelp.

DDAC Digital-to-analogconverter—anelectronicdevice,oftenan

integratedcircuit,thatconvertsadigitalvalueintoacorrespondinganalogvoltageorcurrent.

DAQ Refertodataacquisition.DAQAssistant

Agraphicalinterfaceforconfiguringmeasurementtasks,virtualchannels,andscales.

DAQdevice Adevicethatacquiresorgeneratesdataandcancontainmultiplechannelsandconversiondevices.DAQdevicesincludeplug-indevices,PCMCIAcards,andDAQPaddevices,whichconnecttoacomputerUSBor1394(FireWire)port.SCXImodulesareconsideredDAQdevices.

data Samples.dataacquisition(DAQ)

1. Acquiringandmeasuringanalogordigitalelectricalsignalsfromsensors,transducers,andtestprobesorfixtures.

2. Generatinganalogordigitalelectricalsignals.

dB Decibel—theunitforexpressingalogarithmicmeasureoftheratiooftwosignallevels:dB=20log10V1/V2,forsignalsinvolts.

DC directcurrentdelayfromsample

Theamountoftimetowaitafterreceivingasampleclockedgebeforebeginningtheacquisitionofasample.

delayfromstart

TheamountoftimetowaitafterreceivingaStartTriggerbeforebeginningtheoperation.

determinism Characteristicofasystemthatdescribeshowconsistentlyitcanrespondtoexternaleventsorperformoperationswithinagiventimelimit.

device 1. Aninstrumentorcontrolleryoucanaccessasasingleentitythatcontrolsormonitorsreal-worldI/Opoints.Adeviceoftenisconnectedtoahostcomputerthroughsometypeofcommunication

network.2. SeealsoDAQdeviceandmeasurementdevice.

digital ATTLsignal.Refertoedge.DIO digitalinput/outputDMA directmemoryaccess—Amethodoftransferringdata

betweenabufferandadevicethatisusedmostoftenforhigh-speedoperations.

driver Softwareuniquetothedeviceortypeofdevice,andincludesthesetofcommandsthedeviceaccepts.

drop-downlistbox

Agraphicalboxwithadownarrowbuttonthatletsyouselectvaluesoroptionsfromalist.Toselectavalueoroptionintheselectionbox,clickthedownarrowforacompletelistofvaluesoroptions,thenuseyourarrowkeysormousetoselectavalueoroptionfromthelist.

DSUB D-subminiatureconnectorDUT deviceundertest—adeviceusedfortestingpurposes.

EESeries Astandardarchitectureforinstrumentation-class,

multichanneldataacquisitiondevices.edge AdigitaledgeisasinglerisingorfallingTTLtransition.An

analogedgeisdefinedbytheslope,level,andhysteresissettings.

event Adigitalsignalproducedfromadeviceorcircuit.Foranadvanceddiscussionofevents,refertoEvents.

excitation Supplyingavoltageorcurrentsourcetoenergizeasensororcircuit.

Ffalltime Thetimeforasignaltotransitionfrom90%to10%ofthe

maximumsignalamplitude.filtering Atypeofsignalconditioningthatyoucanusetoremove

unwantedfrequencycomponentsfromthesignalyouaremeasuring.

FIFO AtypeofmemorythatimplementsaFirstInFirstOutstrategyinwhichsamplesareremovedintheordertheywerewritten.FIFOsaretypicallyusedasintermediatebuffersbetweenanADCorDACandthememorybuffer.

floatingsignalsources

Signalsourceswithvoltagesignalsthatarenotconnectedtoanabsolutereferenceorsystemground.

Ggain Thefactorbywhichasignalisamplified,oftenexpressedin

decibels(dB).Gainasafunctionoffrequencyiscommonlyreferredtoasthemagnitudeofthefrequencyresponsefunction.

groundedsignalsources

Signalsourceswithvoltagesignalsthatarereferencedtoasystemground,suchastheearthorabuildingground.Groundedsignalsourcesarealsocalledreferencedsignalsources.

Hhardware Thephysicalcomponentsofacomputersystem,suchasthe

circuitboards,plug-inboards,chassis,enclosures,peripherals,andcables.

hardwaretiming

Ameansofcontrollingsignalgeneration.Adigitalsignal,suchasaclockonaDAQdevice,controlstherateofgeneration.

hardwaretriggering

Aformoftriggeringinwhichthesourceofthetriggerisananalogordigitalsignal.RefertoSoftwareTrigger.

hex Hexadecimal—abase-16numberingsystem.hysteresis Awindowaroundatriggerlevelthatisoftenusedtoreduce

falsetriggeringduetonoiseorjitterinthesignal.Hz Hertz—cyclespersecondofaperiodicsignal.

IIEEEP1451

FamilyofIEEEstandardsdefiningavarietyofsmarttransducerinterfaces.AllofthestandardswithinthisfamilysupporttheconceptofaTEDSthatprovidesself-identificationandplugandplayoperationtotransducers.

IEEEP1451.4

AnIEEEstandardthatdefinestheconceptofplugandplaysensorswithanalogsignals.ThisisaccomplishedwiththeadditionofaTEDSinmemory,typicallyanEEPROM,embeddedwithinthesensorandcommunicatedthroughasimple,low-costserialconnection.

instrumentdriver

Refertodriver.

internalchannel

AphysicalchannelnotaccessiblefromanI/Oconnector.Internalchannelsareoftenusedforcalibrationandareintendedforadvancedapplications.

interrupt Amethodwherebyadevicenotifiesthecomputerofsomeconditiononthedevicethatrequiresthecomputer'sattention.Whenthisconditionisarequestfordataoranotificationofavailabledata,interruptsareusedasadatatransfermechanism.

interruptlevel

Therelativepriorityatwhichadevicecaninterrupt.

I/O Input/Output—thetransferofdatato/fromacomputersysteminvolvingcommunicationschannels,operatorinterfacedevices,and/ordataacquisitionandcontrolinterfaces.

IRQ InterruptReQuest.ISA IndustryStandardArchitecture—Alsoreferstoacommon

PCexpansionbus.isolation Atypeofsignalconditioninginwhichyouisolatethe

transducersignalsfromthecomputer.Isolationmakessurethemeasurementsfromthemeasurementdevicearenotaffectedbydifferencesingroundpotentials.

Jjitter Theamountoftimethattheloopcycletimevariesfromthedesired

time.

LLED light-emittingdiode—asemiconductorlightsource.line Anindividualsignalinadigitalport.Thedifference

betweenabitandalineisthatthebitreferstotheactualdatatransferred,andthelinereferstothehardwarethebitistransferredon.However,thetermslineandbitarefairlyinterchangeable.Forexample,an8-bitportisthesameasaportwitheightlines.

lineardisplacement

Movementinonedirectionalongasingleaxis.

lineardisplacementsensor

Adevicethatmeasureslineardisplacement.

linearization Atypeofsignalconditioninginwhichsoftwarelinearizesthevoltagelevelsfromtransducers,sothevoltagescanbescaledtomeasurephysicalphenomena.

LSB leastsignificantbit—oftenusedtorefertothesmallestvoltagechangedetectablebyanA/DconverterorthesmallestvoltagechangethatcanbegeneratedbyaD/Aconverter.

LVDT Linear-voltagedifferentialtransformer—Asensorusedtomeasurelineardisplacement.AnLVDTconsistsofapassivetransformwithoneprimaryandtwosecondarywindings.TheprimarywindingisexcitedbyanaudiofrequencyrangeACvoltage,whoseimbalancebetweenthesecondarywindings,isproportionaltothedisplacement.Thesecondarywindingsareidentical,butarenormallyconnectedwithoppositepolarity,sothetransduceratrestingpositionwillhavezerooutputvoltage.

MMSeries Astandardarchitectureforinstrumentation-class,

multichanneldataacquisitiondevices.MAX Measurement&AutomationExplorer—Acentralized

configurationenvironmentthatallowsyoutoconfigureallofyourNationalInstrumentsdevices.

measurementdevice

DAQdevicessuchastheMSeriesmultifunctionI/O(MIO)devices,SCXIsignalconditioningmodules,andswitchmodules.

memorybuffer

Refertobuffer.

memorymapping

Atechniqueforreadingandwritingtoadevicedirectlyfromyourprogram,whichavoidstheoverheadofdelegatingthereadsandwritestokernel-levelsoftware.Delegationtothekernelissafer,butslower.Memorymappingislesssafebecauseanentire4KBpageofmemorymustbeexposedtoyourprogramforthistowork,butitisfaster.

microphone Atransducerthatconvertsacousticalwavesintoelectricalsignals.

MIO multifunctionI/O—Designatesacategoryofdataacquisitiondevicesthathavemultipleanaloginputchannels,digitalI/Ochannels,timing,andoptionally,analogoutputchannels.AnMIOproductcanbeconsideredaminiaturemixedsignaltester,duetoitsbroadrangeofsignaltypesandflexibility.ItisalsoknownasmultifunctionDAQ.AnESeriesdeviceisanexampleofanMIOdevice.

module Aboardassemblyanditsassociatedmechanicalparts,frontpanel,optionalshields,andsoon.Amodulecontainseverythingrequiredtooccupyoneormoreslotsinamainframe.SCXIandPXIdevicesaremodules.

multiplexedmode

AnSCXIoperatingmodeinwhichanaloginputchannelsaremultiplexedintoonemoduleoutputsothatthe

cabledDAQdevicehasaccesstothemultiplexedoutputaswellastheoutputsonallothermultiplexedmodulesinthechassisthroughtheSCXIbus.Alsocalledserialmode.

multiplexer Aswitchingdevicewithmultipleterminalsthatsequentiallyconnectseachofitsterminalstoasingleterminal,typicallyathighspeeds.Oftenusedtomeasureseveralsignalswithasingleanaloginputchannel.

multithreading Runningtasksofanapplicationforashortamountoftimetogivetheimpressionofmultipletasksrunningsimultaneously.

NNI-DAQ DriversoftwareincludedwithallNImeasurementdevices.

NI-DAQisanextensivelibraryofVIsandfunctionsyoucancallfromanapplicationdevelopmentenvironment(ADE),suchasLabVIEW,toprogramallthefeaturesofanNImeasurementdevice,suchasconfiguring,acquiringandgeneratingdatafrom,andsendingdatatothedevice.

NI-DAQ7.x IncludestwoNI-DAQdrivers—NI-DAQmxandTraditionalNI-DAQ(Legacy)—eachwithitsownAPI,hardwareconfiguration,andsoftwareconfiguration.

NI-DAQmx ThelatestNI-DAQdriverwithnewVIs,functions,anddevelopmenttoolsforcontrollingmeasurementdevices.TheadvantagesofNI-DAQmxoverearlierversionsofNI-DAQincludetheDAQAssistantforconfiguringchannelsandmeasurementtasksforyourdeviceforuseinLabVIEW,LabWindows/CVI,andMeasurementStudio;increasedperformancesuchasfastersingle-pointanalogI/O;andasimplerAPIforcreatingDAQapplicationsusingfewerfunctionsandVIsthanearlierversionsofNI-DAQ.

NI-DAQmxSimulatedDevice

AreplicaofadevicecreatedusingtheNI-DAQmxSimulatedDeviceoptionintheCreateNewmenuofMAXforthepurposeofoperatingafunctionorprogramwithouthardware.AnNI-DAQmxsimulateddevicebehavessimilarlytoaphysicaldevice.Itsdriverisloaded,andprogramsusingitarefullyverified.

nonlinearity Ameasureinpercentageoffull-scalerange(FSR)oftheworst-casedeviationfromtheidealtransferfunction—astraightline.

ThisspecificationisincludedonlyforDAQproducts,suchassignalconditioningproducts,thatdonothaveanADC.BecauseaproductwiththisspecificationcanalsobeusedwithaDAQproductwithanADC,thisnonlinearityspecificationmustbeaddedtotherelativeaccuracyspecificationoftheDAQproductwiththeADC.

NRSE Nonreferencedsingle-endedmode—allmeasurementsaremadewithrespecttoacommon(NRSE)measurementsystemreference,butthevoltageatthisreferencecanvarywithrespecttothemeasurementsystemground.

Oonboard Providedbythedataacquisitiondevice.onboardchannels

Channelsprovidedbytheplug-indataacquisitiondevice.

onboardclock

Thedefaultsourceforaparticularclock.Usually,thedevicehasdedicatedacircuitforproducingthissignalanditsonlypurposeistoactasthesourceforacertainclock.

onboardmemory

Memoryprovidedbyadevicefortemporarystorageofinputoroutputdata.Typically,onboardmemoryisaFIFO,whichisdistinctfromcomputermemory.

operatingsystem

Base-levelsoftwarethatcontrolsacomputer,runsprograms,interactswithusers,andcommunicateswithinstalledhardwareorperipheraldevices.AlsoreferredtoasOS.

Pparallelmode

AtypeofSCXIoperatingmodeinwhichthemodulesendseachofitsinputchannelsdirectlytoaseparateanaloginputchannelofthedeviceconnectedtothemodule.

patternI/O patterninputandoutput—adigitalI/Ooperationonwhichaclocksignalinitiatesadigitaltransfer.Becausetheclocksignalisaconstantfrequency,youcangenerateandreceivepatternsataconstantrate.

PCI peripheralcomponentinterconnect—ahigh-performanceexpansionbusarchitectureoriginallydevelopedbyInteltoreplaceISAandEISA.PCIhasachievedwidespreadacceptanceasastandardforPCsandworkstations,anditoffersatheoreticalmaximumtransferrateof132Mbytes/s.

PCMCIA Anexpansionbusarchitecturethathasfoundwidespreadacceptanceasadefactostandardinnotebook-sizecomputers.PCMCIAoriginatedasaspecificationforadd-onmemorycardswrittenbythePersonalComputerMemoryCardInternationalAssociation.

PFI programmablefunctioninterface—generalpurposeinputterminals,fixedpurposeoutputterminals.ThenameofthefixedoutputsignalisoftenplacedontheI/Oconnectornexttotheterminalasahint.

physicalchannel

Refertochannel.

PID proportionalintegralderivative—Combinationofproportional,integral,andderivativecontrolactions.Referstoacontrolmethodinwhichthecontrolleroutputisproportionaltotheerror,itstimehistory,andtherateatwhichitischanging.Theerroristhedifferencebetweentheobservedanddesiredvaluesofavariablethatisundercontrolaction.

pin Refertoterminal.Poisson's Thenegativeratioofthestraininthetransversedirection

Ratio (perpendiculartotheforce)tothestrainintheaxialdirection(paralleltotheforce).

port Acollectionofdigitallines.Usuallythelinesaregroupedintoeithera8-bitor32-bitport.MostESeriesdeviceshaveone8-bitport.

portwidth Thenumberoflinesinaport.Forexample,mostESeriesdeviceshaveoneportwitheightlines;therefore,theportwidthiseight.

positionsensor

Refertolineardisplacementsensor.

posttriggersamples

IfthereisnoReferenceTrigger,posttriggersamplesarethedataacquiredafterthetaskisstarted.IfthereisaReferenceTrigger,thisisthedataacquiredaftertheReferenceTrigger.

plugandplaydevices

DevicesthatdonotrequireDIPswitchesorjumperstoconfigureresourcesonthedevices.Alsocalledswitchlessdevices.

plugandplaysensors

AtransducerwithanassociatedTEDS—includesbothVirtualTEDSandsmartTEDSsensors.

pretriggersamples

DataacquiredbeforetheoccurrenceoftheReferenceTrigger.

pretriggering Thetechniqueusedonameasurementdevicetokeepacircularbufferfilledwithsamples,sothatwhentheReferenceTriggerconditionsaremet,thebufferincludessamplesleadinguptothetriggerconditionaswellassamplesacquiredimmediatelyafterthetrigger.

programmedI/O

Adatatransfermechanisminwhichabufferisnotusedandinstead,thecomputerreadsandwritesdirectlytothedevice.

propagationdelay

Theamountoftimerequiredforasignaltopassthroughacircuit.

pulsedoutput

Aformofcountersignalgenerationbywhichapulseisgeneratedwhenacounterreachesacertainvalue.

PWM pulse-widthmodulation

PXI PCIeXtensionsforInstrumentation—arugged,opensystemformodularinstrumentationbasedonCompactPCI,withspecialmechanical,electrical,andsoftwarefeatures.ThePXIstandardwasoriginallydevelopedbyNationalInstrumentsin1997andisnowmanagedbythePXISystemsAlliance.

PXItriggerbus

ThetimingbusthatconnectsPXIDAQdevicesdirectly,bymeansofconnectorsbuiltintothebackplaneofthePXIchassis,forprecisesynchronizationoffunctions.ThisbusisfunctionallyequivalenttotheRTSIbusforPCIDAQdevices.

Rrange Theminimumandmaximumanalogsignallevelsthatthe

ADCcandigitize.raw Datathathasnotbeenchangedinanyway.Forinput,data

isreturnedexactlyasreceivedfromthedevice.Foroutput,dataiswrittenasistothedevice.Refertounscaledandscaled.

realtime Apropertyofaneventorsysteminwhichsamplesareprocessedastheyareacquiredinsteadofbeingaccumulatedandprocessedatalatertime.

referencedsignalsource

Signalsourceswithvoltagesignalsthatarereferencedtoasystemground,suchastheearthorabuildingground.Alsocalledgroundedsignalsources.

resolution Thesmallestamountofinputsignalchangethatadeviceorsensorcandetect.Thetermdiscriminationisalsousedforresolution.

risetime Thetimeforasignaltotransitionfrom10%to90%ofthemaximumsignalamplitude.

route Aconnectionbetweenapairofterminals.Anytimethesourceordestinationterminalofasignalisspecified,arouteiscreated.

RSE Referencedsingle-endedmode—allmeasurementsaremadewithrespecttoacommonreferencemeasurementsystemoraground.Alsocalledagroundedmeasurementsystem.

RTD Resistancetemperaturedetector—ametallicprobethatmeasurestemperaturebasedonitscoefficientofresistivity.

RTSIbus Real-timesystemintegrationbus—theNItimingbusthatconnectsDAQdevicesdirectly,bymeansofconnectorsontopofthedevices,forprecisesynchronizationoffunctions.ThisbusisfunctionallyequivalenttothePXITriggerbusforPXIDAQdevices.

RVDT rotaryvariabledifferentialtransformer—asensorwhoseoutputsignalrepresentstherotationoftheshaft.

Ss secondsS samples.Refertosample.S/s samplespersecond—usedtoexpresstherateatwhicha

measurementdevicesamplesananalogsignal.sample Asinglemeasurementfromasinglechannelor,foroutput,

asinglegenerationtoasinglechannel.sampleclock

Theclockthatinitiatesanacquisitionofonesamplefromeachchannelinthescanlist.Forexample,witheachsampleclockpulse,MSeriesdevicesacquireasampleoneachanaloginputchannelinataskbymultiplexingeachchannelthroughasingleADC.Onsimultaneoussamplingdevices,thesampleclockinitiatesthesimultaneousacquisitionofonesamplefromeachchannelinthetaskthroughadedicated,per-channelADC.Nomultiplexing(andthereforenoconvertclock)isnecessaryforSSeriesdevices.

sampleclockrate

Refertosamplerate.

samplerate Thenumberofsamplesperchannelpersecond.Forexample,asamplerateof10S/smeanssamplingeachchannel10timespersecond.

scale Datathathasbeenmathematicallytransformedintoengineeringunits.Othermanipulationsalsocanbedonesuchasreorderingtomatchthechannelorder.

scanning Methodofsequentiallyconnectingchannels.SCC Signalconditioningcomponent—lowchannelcountanalog

ordigitalI/OmodulesforconditioningDAQsystems.SCXI SignalConditioningeXtensionsforInstrumentation—the

NIproductlineforconditioninglow-levelsignalswithinanexternalchassisnearsensorssothatonlyhigh-levelsignalsaresenttomeasurementdevicesinthenoisyPCenvironment.SCXIisanopenstandardavailableforallvendors.

sensor Adevicethatrespondstoaphysicalstimulus(heat,light,sound,pressure,motion,flow,andsoon)andproducesacorrespondingelectricalsignal.

signal Ameansofconveyinginformation.Ananalogwaveform,aclock,andasingledigital(TTL)edgeareallexamplesofsignals.

signalconditioning

Themanipulationofsignalstopreparethemfordigitizing.

smartTEDSsensor

Atransducerwithabuilt-inself-identificationEEPROMthatprovidestheTEDS.

softwaretiming

Ameansofcontrollingsignalgeneration.Thesoftware,suchasNI-DAQmx,andtheoperatingsystemcontroltherateofgeneration.

softwaretrigger

AVIorfunctionthat,whenitexecutes,triggersanactionsuchasstartinganacquisition.

sourceimpedance

Aparameterofsignalsourcesthatreflectscurrent-drivingabilityofvoltagesources(lowerisbetter)andthevoltage-drivingabilityofcurrentsources(higherisbetter).

staticAO Analogoutputoperationsthatusesoftwaretiming.staticdigitalI/O

Software-timeddigitalI/Ooperationsthatdonotinvolvetheuseofcontrolsignalsindatatransfers.Alsoknownassoftware-timedI/OorunstrobedI/O.

strain Theamountofdeformationofabodyduetoanappliedforce.

strobedI/O Anyoperationinwhicheverydatatransferistimedbyhardwaresignals.Inthecaseofsampleclocktiming,thishardwaresignalisaclockedge.InthecaseofhandshakingI/O,hardwaresignalsinvolvetwoorthreehandshakinglines.

STC systemtimingcontrollersynchronous 1. Hardware—asignalthatoccursorisacteduponin

synchronywithanothersignal,suchasareferenceclock.

2. Software—aVIorfunctionthatbeginsanoperation

andreturnsonlywhentheoperationiscomplete.

Ttask InNI-DAQmx,acollectionofoneormorechannels,

timing,andtriggeringandotherpropertiesthatapplytothetaskitself.Conceptually,ataskrepresentsameasurementorgenerationyouwanttoperform.

taskbuffer Refertobuffer.TCR temperaturecoefficientofresistance—theaverage

resistancechangeperonedegreeattemperaturesbetween0°Cand100°C.

TEDS transducerelectronicdatasheet—standardizeddatastructure,definedbyIEEE1451.4,fordescribingsensors,typicallystoredinnonvolatilememorywithinasensor.Themanufacturerofthesensorstores,intothismemory,initialinformationsuchasmanufacturername,sensortype,modelnumber,serialnumber,andcalibrationdata.TheTEDSdatastructurealsoincludesspaceforcustominformationsuchaschannelID,location,position,direction,tagnumber,etc.Alternatively,theTEDSdatamaybestoredinafileordatabaserecordasaVirtualTEDS.ForinformationonIEEE1451.4-compliantTEDSsensors,refertowww.ni.com/pnp.

TEDSClassISensor

AsmartTEDSsensorwithaconstant-currentpoweredtransducerwithatwo-wireinterface,suchasanaccelerometer.ClassItransducersalsoincludediodesoranalogswitcheswithwhichthemultiplexingoftheanalogsignalwiththedigitalTEDSinformationonthesinglepairofwiresispossible.Thedigitalportionofthemixed-modeinterface(Class1orClass2)isbasedonthe1-WireprotocolfromMaxim/DallasSemiconductor.

TEDSClassIISensor

AsmartTEDSsensorwithseparatewiresfortheanaloganddigitalportionsoftheTEDSmixed-modeinterface.Theanaloginput/outputofthetransducerisleftunmodified,andthedigitalTEDScircuitisaddedinparallel,suchasthermocouples,RTDs,andbridge-basedsensors.Thedigitalportionofthemixed-modeinterface

(Class1orClass2)isbasedonthe1-WireprotocolfromMaxim/DallasSemiconductor.

terminal AnamedlocationonaDAQdevicewhereasignaliseithergenerated(outputorproduced)oracquired(inputorconsumed).

terminalcount

Whencountingup,anNbitcounterreachesitsterminalcountat2N-1.AnNbitcountercountingdownreachesitsterminalcountat0.

thermistor Asemiconductorsensorthatproducesarepeatablechangeinelectricalresistanceasafunctionoftemperature.Mostthermistorshaveanegativetemperaturecoefficient.

thermocouple Atemperaturesensorcreatedbyjoiningtwodissimilarmetals.Thejunctionproducesasmallvoltageasafunctionofthetemperature.

threshold Thevoltagelevelasignalmustreachforatriggertooccur.

tick Adigitaledgeofaclock.timebase Aclockthatisdivideddowntoproduceanotherclockora

clockprovidedtoacounterformeasuringelapsedtime.TraditionalNI-DAQ(Legacy)

AnupgradeoftheearlierversionofNI-DAQ.TraditionalNI-DAQ(Legacy)hasthesameVIsandfunctionsandworksthesamewayasNI-DAQ6.9.x,exceptyoucanusebothTraditionalNI-DAQ(Legacy)andNI-DAQmxonthesamecomputer,andsomehardwareisnolongersupported.

transducer Refertosensor.transducerexcitation

Atypeofsignalconditioningthatusesexternalvoltagesandcurrentstoexcitethecircuitryofasignalconditioningsystemintomeasuringphysicalphenomena.

trigger Anysignalthatcausesadevicetoperformanaction,suchasstartinganacquisition.

TTL Transistor-transistorlogic—asignalhavingtwodiscretelevels,ahighandalowlevel.

Uunipolar Asignalrangethatisalwayspositive(forexample,0to+10

V).unscaled Samplesintheintegerformthatthehardwareproducesor

requires.Althoughnomathematicaltransformationsareappliedtounscaleddata,othermanipulationsmaybedonesuchasreorderingtomatchthechannelorder.

unstrobedI/O

RefertostaticdigitalI/O.

USBDAQ

AUSB-basedfamilyofdevicesusedforanaloginput,analogoutput,digitalinput/output,andcounter/timerapplications.SomeexampledevicesincludetheNIUSB-9201,NIUSB-9211,NIUSB-9215,NIUSB-9221,NIUSB-9233,andNIUSB-9237devices.ThesedevicesarealsoreferredtoasUSBDAQwithIntegratedSignalConditioning.

VV voltsVI Refertovirtualinstrument.virtualchannel

Refertochannel.

virtualinstrument

AprograminLabVIEWthatmodelstheappearanceandfunctionofaphysicalinstrument.

VISA VirtualInstrumentationSoftwareArchitecture.

Wwaveformdatatype

ALabVIEWdatatypethatbundlestiminginformationalongwiththedata.

WDT Refertowaveformdatatype.

ImportantInformationWarrantyCopyrightTrademarksPatentsWarningRegardingUseofNIProducts

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TechnicalSupportandProfessionalServicesVisitthefollowingsectionsoftheNationalInstrumentsWebsiteatni.comfortechnicalsupportandprofessionalservices:

Support—Onlinetechnicalsupportresourcesatni.com/supportincludethefollowing:

Self-HelpResources—Foranswersandsolutions,visittheaward-winningNationalInstrumentsWebsiteforsoftwaredriversandupdates,asearchableKnowledgeBase,productmanuals,step-by-steptroubleshootingwizards,thousandsofexampleprograms,tutorials,applicationnotes,instrumentdrivers,andsoon.FreeTechnicalSupport—AllregisteredusersreceivefreeBasicService,whichincludesaccesstohundredsofApplicationsEngineersworldwideintheNIDeveloperExchangeatni.com/exchange.NationalInstrumentsApplicationsEngineersmakesureeveryquestionreceivesananswer.Forinformationaboutothertechnicalsupportoptionsinyourarea,visitni.com/servicesorcontactyourlocalofficeatni.com/contact.

TrainingandCertification—Visitni.com/trainingforself-pacedtraining,eLearningvirtualclassrooms,interactiveCDs,andCertificationprograminformation.Youalsocanregisterforinstructor-led,hands-oncoursesatlocationsaroundtheworld.SystemIntegration—Ifyouhavetimeconstraints,limitedin-housetechnicalresources,orotherprojectchallenges,NationalInstrumentsAlliancePartnermemberscanhelp.Tolearnmore,callyourlocalNIofficeorvisitni.com/alliance.DeclarationofConformity(DoC)—ADoCisourclaimofcompliancewiththeCounciloftheEuropeanCommunitiesusingthemanufacturersdeclarationofconformity.Thissystemaffordstheuserprotectionforelectroniccompatibility(EMC)andproductsafety.YoucanobtaintheDoCforyourproductbyvisitingni.com/certification.CalibrationCertificate—Ifyourproductsupportscalibration,youcanobtainthecalibrationcertificateforyourproductat

ni.com/calibration.Ifyousearchedni.comandcouldnotfindtheanswersyouneed,contactyourlocalofficeorNIcorporateheadquarters.YoualsocanvisittheWorldwideOfficessectionofni.com/niglobaltoaccessthebranchofficeWebsites,whichprovideup-to-datecontactinformation,supportphonenumbers,emailaddresses,andcurrentevents.

BranchOfficesOffice TelephoneNumberAustralia 1800300800Austria 43662457990-0Belgium 32(0)27570020Brazil 551132623599Canada 8004333488China 862150509800CzechRepublic 420224235774Denmark 4545762600Finland 358(0)972572511France 33(0)157662424Germany 49897413130India 918041190000Israel 972036393737Italy 390241309277Japan 0120-527196/81354722970Korea 820234513400Lebanon 961(0)1332828Malaysia 1800887710Mexico 018000100793Netherlands 31(0)348433466NewZealand 0800553322Norway 47(0)66907660Poland 48223390150Portugal 351210311210Russia 74957836851Singapore 18002265886Slovenia 38634254200

SouthAfrica 270118058197Spain 34916400085Sweden 46(0)858789500Switzerland 41562005151Taiwan 8860223772222Thailand 6622786777Turkey 902122793031UnitedKingdom 44(0)1635523545UnitedStates(Corporate) 5126830100