daq assistant help...done, the daq assistant opens, and you can configure timing, triggering,...

DAQAssistantHelpJanuary2008,370467L-01ThishelpfiledescribeshowtousetheDAQAssistanttointeractivelyconfigurecommonmeasurementtasks,globalvirtualchannels,orscales.InNILabVIEW7.xandlater,NILabWindows™/CVI™7.xandlater,orNIMeasurementStudio7.xandlater,youalsocanusetheDAQAssistanttogenerateNI-DAQmxcodefromyourtasksandglobalvirtualchannels.YoucanalsousetheDAQAssistantwithNILabVIEWSignalExpress2.xandlater.Tonavigatethishelpfile,usetheContents,Index,andSearchtabstotheleftofthiswindow.Formoreinformationaboutthishelpfile,refertothefollowingtopics:Conventions—formattingandtypographicalconventionsusedinthishelpfileRelatedDocumentationGlossaryImportantInformationTechnicalSupportandProfessionalServicesTocommentonNationalInstrumentsdocumentation,refertotheNationalInstrumentsWebsite.©Copyright2003–2008NationalInstrumentsCorporation.Allrightsreserved.

RelatedDocumentationThefollowingdocumentscontaininformationthatyoumightfindhelpfulasyouusethishelpfile:

DAQGettingStartedGuide—ThisguidedescribeshowtoinstalltheNI-DAQmxdriversoftware,yourdataacquisition(DAQ)device,andhowtoconfirmthatyourdeviceisoperatingproperly.LabVIEWHelp—ThishelpfilecontainsinformationaboutLabVIEWpalettes,menus,tools,VIs,andfunctions.Thishelpfilealsoincludesstep-by-stepinstructionsforusingLabVIEWfeatures.InLabVIEW,selectHelp.LabWindows/CVIHelp—TheLabWindows/CVIHelpincludesthefollowingsections:

UsingLabWindows/CVI—Informationaboutwindows,menus,commands,dialogboxes,andoptionsforcustomizingconfigurationdefaults.LibraryReference—ReferenceinformationforallLabWindows/CVIlibraryfunctions.ProgrammerReference—InformationaboutdevelopingprogramsinLabWindows/CVI.ExamplePrograms—DescriptionsofeachoftheexampleprogramsincludedwithLabWindows/CVI.ToolsLibrary—DescriptionsoftheadditionalinstrumentdriversincludedwithLabWindows/CVI.

InLabWindows/CVI,selectHelp»Contents.Measurement&AutomationExplorerHelpforNI-DAQmx—ThishelpfilecontainsinformationonconfiguringandtestingDAQdevices,SCXIdevices,PXIsystems,SCCdevices,serialandparallelports,andRTSIcablesusingMeasurement&AutomationExplorer(MAX)forNI-DAQmx,andinformationonspecialconsiderationsforoperatingsystems.InMAX,selectHelp»HelpTopics»NI-DAQmx.NIMeasurementStudioHelp—ThishelpfilecontainsinformationaboutusingMeasurementStudioforMicrosoftVisualC++,Visual

Basic,andthe.NETplatform.InVisualStudio.NET,selectHelp»Contents.NI-DAQmxHelp—ThishelpfiledescribeshowtouseNI-DAQmxtoprogramyourNationalInstrumentsdevice.NI-DAQmxisthesoftwareyouusetocommunicatewithandcontrolyourNIdevice.SelectStart»AllPrograms»NationalInstruments»NI-DAQ.TakinganNI-DAQmxMeasurementinLabVIEW—ThistutorialteachesyouhowtotakeanNI-DAQmxmeasurementinLabVIEW7.xorlaterusingtheDAQAssistant.TheDAQAssistantisagraphicalinterfaceforconfiguringmeasurementtasks,globalvirtualchannels,andscales.YoualsocanusetheDAQAssistanttogenerateNI-DAQmxcodefromthetask.RefertoTakinganNI-DAQmxMeasurementinLabVIEWintheLabVIEWHelp.

UsingHelpConventionsNavigatingHelpSearchingHelpPrintingThisHelpFile

ConventionsThishelpfileusesthefollowingconventions:<> Anglebracketsthatcontainnumbersseparatedbyanellipsisrepresentarangeofvalues

associatedwithabitorsignalname—forexample,DIO<3..0>.

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

Thisicondenotesacaution,whichadvisesyouofprecautionstotaketoavoidinjury,dataloss,orasystemcrash.

bold Boldtextdenotesitemsthatyoumustselectorclickoninthesoftware,suchasmenuitemsanddialogboxoptions.Boldtextalsodenotesparameternames,emphasis,oranintroductiontoakeyconcept.

darkred Textinthiscolordenotesacaution.

green Underlinedtextinthiscolordenotesalinktoahelptopic,helpfile,orWebaddress.

italic Italictextdenotesvariables,emphasis,crossreferences,oranintroductiontoakeyconcept.Italictextalsodenotestextthatisaplaceholderforawordorvaluethatyoumustsupply.

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.

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

BooleanExpressionsClickthe buttontoaddBooleanexpressionstoasearch.ThefollowingBooleanoperatorsareavailable:

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

SearchOptionsUsethefollowingcheckboxesontheSearchtabtocustomizeasearch:

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.

GettingStartedTheDAQAssistanthelpsyouconfiguretasks,virtualchannels,andscalesusingagraphicalinterface.YoucanlaunchtheDAQAssistantfromyourNationalInstrumentsapplicationsoftwaresuchasLabVIEW,LabVIEWSignalExpress,LabWindows/CVI,orMeasurementStudio.YoualsocanlaunchtheDAQAssistantfromMAX.UsingtheDAQAssistant,youcandothefollowingthings:

CreateandedittasksandvirtualchannelsAddvirtualchannelstotasksCreateandeditscalesTestyourconfigurationSaveyourconfigurationGeneratecodeinyourNIapplicationsoftwareforuseinyourapplicationViewconnectiondiagramsforyoursensors

NoteYoumustuseversion7.xorlaterofLabVIEW,LabWindows/CVI,orMeasurementStudioorversion2.xorlaterofLabVIEWSignalExpresstousetheDAQAssistant.

ChannelsandTasksPhysicalChannelsandVirtualChannelsAphysicalchannelisaterminalorpinatwhichyoucanmeasureorgenerateananalogordigitalsignal.Avirtualchannelisacollectionofsettingssuchasaname,aphysicalchannel,inputterminalconnections,thetypeofmeasurementorgeneration,andcanincludescalinginformation.InNI-DAQmx,virtualchannelsareintegraltoeverymeasurement.InNI-DAQmx,usetheDAQAssistant,accessiblefromMAXorNIapplicationsoftwaretoconfigurechannelsandmeasurementtasks.RefertotheDAQAssistantHelpandMeasurement&AutomationExplorerHelpforNI-DAQmx.YoucanalsoconfigurevirtualchannelswiththeNI-DAQmxAPIinyourapplicationprogram.InTraditionalNI-DAQ(Legacy)andearlierversions,youcanuseMAXtoconfigurevirtualchannels,anoptionalwaytorecordwhichchannelsarebeingusedfordifferentmeasurements.

TasksAtask,animportantconceptforNI-DAQmx,isacollectionofoneormorevirtualchannelswithtiming,triggering,andotherproperties.Conceptually,ataskrepresentsameasurementorgenerationyouwanttoperform.Youcansetupandsavealloftheconfigurationinformationinataskandusethetaskinanapplication.

GlobalVirtualChannelsandLocalVirtualChannelsInNI-DAQmx,youcanconfigurevirtualchannelsaspartofataskorseparatefromatask.Virtualchannelscreatedinsideataskarelocalvirtualchannels.Virtualchannelsdefinedoutsideataskareglobalvirtualchannels.YoucancreateglobalvirtualchannelsinMAXorinyourapplicationsoftwareandsavetheminMAX.Youcanuseglobalvirtualchannelsinanyapplicationoraddthemtoanumberofdifferenttasks.Ifyoumodifyaglobalvirtualchannel,thechangeaffectsalltasksinwhichyoureferencethatglobalvirtualchannel.Inmostcases,itissimplertouselocalvirtualchannels.

NoteIfyouareusingLabVIEW8.0andlater,youcanalsocreatetasksandchannelslocaltoaLabVIEWProject.

UsingtheDAQAssistantinYourApplicationUsingtheDAQAssistant,youcancreate,configure,andsavevirtualchannelsortasksforuseinyourapplications.IfyouareusingNIapplicationsoftware,youalsocangeneratecodebasedonataskorvirtualchannel.RefertoLabVIEWHelp,LabWindows/CVIHelp,MeasurementStudioHelp,orNI-DAQmxKeyConceptsformoreinformationaboutprogrammingwithyourtaskorglobalchannel.

OpeningtheDAQAssistantYoucanopentheDAQAssistantfromyourNIapplicationsoftwareorfromMAX.WhenyouopentheDAQAssistant,awizardpromptsyoufortheinformationneededtocreateyournewtask.Whenthewizardisdone,theDAQAssistantopens,andyoucanconfiguretiming,triggering,measurement-specificsettings,andscaling.YoucanalsousetheDAQAssistanttocreateaglobalvirtualchannel.YoucanopentheDAQAssistanttocreateataskin:

LabVIEWLabWindows/CVIMeasurementStudioMAX

YoucanalsousetheDAQAssistantinLabVIEWSignalExpresstocreateDAQstepsortouseglobalvirtualchannelsinyourproject.

OpeningtheDAQAssistantinLabVIEWYoucanopentheDAQAssistanttocreateataskinoneofthefollowingways:

PlacetheDAQmxTaskNamecontrolonthefrontpanel.Right-clickthecontrol,andselectNewDAQmxTask.IfyouareusingLabVIEW8.0andlater,youcancreateatasklocaltotheProject,oryoucancreateataskinMAX.TocreateataskinaProject,right-clickMyComputerintheProjectExplorerwindow.Then,selectNew»Task.InLabVIEW7.x,clicktheConfigurepull-downmenuonthemainLabVIEWlaunchscreenandselectCreateNewTask(DAQAssistant).PlacetheDAQAssistantExpressVIontheblockdiagram.ThisVIcreatestasksthatarefullycontainedinasingleVI.

NoteIfyouconfigureataskusingtheDAQAssistantExpressVI,thetaskislocaltotheapplicationandcannotbesavedtoMAXforuseinotherapplications.YoumustconverttheDAQAssistantExpressVItoanNI-DAQmxTasktousethetaskinotherapplications.YoucanalsogeneratecodefromtheDAQAssistantExpressVI.Right-clicktheDAQAssistantExpressVIonthefrontpanelinLabVIEWandselectGenerateNI-DAQmxCode.

InLabVIEW7.xorlater,selectFile»NewandbrowsetheFromTemplatesfoldertoDataAcquisitionwithNI-DAQmx.

RefertoTakinganNI-DAQmxMeasurementinLabVIEWintheLabVIEWHelpforstep-by-stepinstructionsforcreatingataskinLabVIEWandgeneratingcodebasedonthetask.FormoreinformationaboutcreatingtasksandchannelswithProjectinLabVIEW,refertotheLabVIEWHelp.AfteropeningtheDAQAssistant,createthenewtask.

OpeningtheDAQAssistantinLabWindows/CVIToopentheDAQAssistant,selectTools»Create/EditDAQmxTasks.IntheCreate/EditDAQmxTasksdialogbox,youcanchoosetocreateataskinMAXorintheLabWindows/CVIproject.YoumustuseMAXtocreateglobalvirtualchannelsforuseinLabWindows/CVI.ForinformationaboutthedifferencesbetweencreatingataskintheprojectorinMAX,refertotheLabWindows/CVIHelp.YoualsocancreateaMAX-basedtaskinLabWindows/CVIwhenyouselectNewTaskfromtheTaskNamecontrolintheDAQmxLoadTaskfunctionpanel.AfteropeningtheDAQAssistant,createthenewtask.

OpeningtheDAQAssistantinMAXToopentheDAQAssistant,completethefollowingsteps:

1. Right-clickDataNeighborhood,andselectCreateNewfromtheshortcutmenu.IfyouareusingaremotesystemrunningLabVIEWReal-Time,expandRemoteSystems,findandexpandyourtarget,thenright-clickDataNeighborhoodandselectCreateNew.

2. SelectNI-DAQmxTaskintheCreateNewwindow.3. ClickNext.TheDAQAssistantopens.4. Createyourtask.5. ClickSaveTasktosavethetasktoMAX.

TipYoucanalsoright-clickyourdeviceunderDevicesandInterfacesandselectCreateNewtolaunchtheDAQAssistantfromMAX.

OpeningtheDAQAssistantinMeasurementStudioTouseaDAQmxtaskclassinaMeasurementStudioapplication,youmustfirstcreatetheDAQmxtaskclasswithintheapplication.YoumustuseMAXtocreateglobalvirtualchannelsforuseinMeasurementStudio.CompletethefollowingstepstocreateaDAQmxtaskclass:

1. OpentheprojectinwhichyouwanttocreateaDAQmxtaskclass.2. SelectProject»AddNewItemtoopentheAddNewItemdialog

box.3. IntheCategoriespane,selectMeasurementStudio»Assistants.4. IntheTemplatespane,selectDAQmxTask.5. SpecifyanamefortheDAQmxtaskfileandclickOpen.The

nameyouchooseforthefilebecomestheclassname.6. IntheNewDAQmxTaskdialogbox,specifywhethertocreatea

newtaskortomakeaprojectcopyofaglobaltaskthatyoucreateinMAX.

NoteIfyouchooseaglobaltaskandmakechangestothetask,thosechangesarenotsavedtotheglobaltaskstoredinMAX.

7. ClickFinish.TheDAQAssistantopensforyoutocreatethenewtask.

Afteryoucompletethesesteps,theDAQAssistantaddsa.mxbfiletotheproject.The.mxbfilestorestheDAQmxtaskclassconfigurationinformation.TheDAQAssistantaddsreferencestoappropriateNIclasslibrariestotheproject.

GlobalVirtualChannelsToopentheDAQAssistanttocreateglobalvirtualchannels,completethefollowingsteps:

NoteIfyouareusingLabWindows/CVIorMeasurementStudio,youmustcreateyourglobalvirtualchannelsinMAX.

1. InMAX,right-clickDataNeighborhoodandselectCreateNew.IfyouareusingaremotesystemrunningLabVIEWReal-Time,expandRemoteSystems,findandexpandyourtarget,thenright-clickDataNeighborhoodandselectCreateNew.

2. IntheCreateNewwindow,selectNI-DAQmxGlobalVirtualChannelandclickNext.TheDAQAssistantopens.YoualsocanopentheDAQAssistantdirectlywithinLabVIEW,LabWindows/CVI,orMeasurementStudioversion7.xorlater:

InLabVIEWandLabVIEWReal-Time,usetheDAQmxGlobalChannelcontroltoopentheDAQAssistant.Right-clickthecontrolandselectNewChannel(DAQAssistant).IfyouareusingLabVIEW8.0orlater,youcancreatechannelslocaltoaLabVIEWProject,oryoucancreatechannelsinMAX.TocreatechannelsinaProject,right-clickMyComputerintheProjectExplorerwindow.Then,selectNew»Channel.

3. InLabVIEW7.x,clicktheConfigurepull-downmenuandselectCreateDAQmxChannel(DAQAssistant).

4. InLabWindows/CVIorMeasurementStudio,firstyoumustcreateataskaspreviouslydescribed.IntheDAQAssistant,clickAddExistingDAQmxGlobalChannelstoaddglobalvirtualchannelstoyourtask.YoumustuseMAXtocreateglobalvirtualchannels.

5. Configuretheglobalvirtualchannel.6. Saveyourconfiguration.

IfyouopenedtheDAQAssistantfromLabVIEWorLabWindows/CVI,clickOK.IfyouopenedtheDAQAssistantfromMeasurementStudio,selectFile»Save.

IfyouopenedtheDAQAssistantfromMAX,clickSaveChannel.

Younowcanusetheglobalvirtualchannelinanapplicationoraddtheglobalvirtualchanneltoatask.Refertotheapplicationsoftwaredocumentationformoreinformationaboutusingaglobalvirtualchannelorgeneratingcode.

UsingtheDAQAssistantinLabVIEWSignalExpressYoucanusetheDAQAssistantwithLabVIEWSignalExpresstocreateDAQsteps.ToopentheDAQAssistantinLabVIEWSignalExpress,completethefollowingsteps:

1. ClickAddStep.2. SelecteitherAcquireSignals»DAQmxAcquireorGenerate

Signals»DAQmxGenerate.3. SelecttheI/Otype,suchasanaloginput,foryourmeasurement.4. Selectthemeasurementtype,suchasvoltage.5. TheDAQAssistantopens,beginningwiththeConfigurationtab.

Youcanconfiguresettingsandtestyourstep.

CreatingaTaskorGlobalVirtualChannelAftertheDAQAssistantopens,completethefollowingstepstocreateanewtaskorglobalvirtualchannel:

1. SelectanI/Otype,suchasanaloginput.2. Selectthemeasurementorgenerationtoperform.Youcanlater

addmultiplemeasurementtypestoatask,butyoumustfirstcreatethetaskwithonemeasurementtype.

3. Selectthesensortouse,ifapplicableforthatmeasurement.4. Adialogboxforthetaskyouspecifiedpromptsyoutoselectthe

physicalchannelsfromwhichtocreatelocalvirtualchannelsinthetask.Alternatively,youcanaddglobalvirtualchannelstothetask,orcopyinformationfromanexistingglobalvirtualchanneltolocalvirtualchannels.IfyoursystemisconfiguredwithaTEDSsensor,clicktheTEDStab.Selectthephysicalchannel(s).TheDAQAssistantimportsthesettingfromthesensor,andusestheinformationtocreatethetask.ClickNext.

NoteForhardwarethatsupportsmultiplechannelsinatask,youcanselectmultiplechannelstoaddtoyourtaskatthesametime.

5. Typethenewtaskorglobalvirtualchannelname.ClickFinish.6. Configuremeasurement-specificsettings,timing,triggering,and

scaling,ifnecessary.IfoneormorechannelsareconfiguredforTEDSsensors,somesettingsloadedfromTEDSarenoteditable.

7. Saveyourconfiguration.NoteInatask,youcanaddchannelsofthesameordifferentmeasurementtypes.

AddingMultipleChannelstoTasksForhardwarethatsupportsmultiplephysicalchannelsinatask,youcanselectmultiplechannelstoaddtothetaskatthesametime.Toselectparticularphysicalchannels,holdthe<Ctrl>keywhileselectingthechannels.Toselectarangeofphysicalchannels,clickthefirstphysicalchannel,thenpressandholdthe<Shift>key,andselectthelastphysicalchannelintherange.Allphysicalchannelsbetweenthetwoselectionsarehighlighted.YoucanalsoselectmultipleglobalvirtualchannelsandanyTEDSchannelsyouhaveconfigured.WhenyouclicktheAddChannelsbutton,alistofallchannelsofthesameI/Otypeasyourtaskappears.Thislistincludeschannelsfromalldevicesinyoursystem.Unlessyourhardwaresupportsmultidevicetasks,youcanaddonlychannelsfromthesamedevicetothetask.Youcanalsocreateataskwithmultiplechannelsofdifferentmeasurementtypes.

DuplicatingNI-DAQmxGlobalVirtualChannelsTocopyaglobalvirtualchannel,completethefollowingsteps:

1. ExpandDataNeighborhood.2. ExpandNI-DAQmxGlobalVirtualChannels.3. Right-clicktheglobalvirtualchannelyouwanttocopy.4. SelectDuplicate.5. Adialogboxpromptsyoutoselectphysicalchannelsfromalistof

validchannelsforthemeasurementtype.Selectthephysicalchannelstouseinthenewglobalvirtualchannels.TheDAQAssistantgeneratesanIDforeachnewglobalchannel,consistingoftheoriginalIDwithanincrementednumberappendedtotheend.

6. ClickOK.

CreatingaTaskwithMultipleMeasurementTypesTocreateataskwithmultiplemeasurementtypes,firstcreateataskwithaninitialmeasurementtype.Then,clicktheAddChannelsbuttontoaddthenextchannel(s).

NoteYoucanhavemultiplemeasurementtypes,suchasvoltage,temperature,andpressure,inthesametask.However,yourtaskmustcontainonlyonemeasurementclass,suchasanaloginputoranalogoutput.

WhenyouclicktheAddChannelsbutton,alistofallchannelsofthesameI/Otypeasyourtaskappears.Thislistincludeschannelsfromalldevicesinyoursystem.Unlessyourhardwaresupportsmultidevicetasks,youcanaddonlychannelsfromthesamedevicetothetask.

NamingChannels,Tasks,andScalesUsethefollowingguidelinestonameyourchannels,tasks,andscales:

Useanyalphanumericcharacters.Donotusenon-alphanumericcharacterswiththefollowingexceptions:

InNI-DAQmx7.4orlater,dashesareallowedinchannel,task,andscalenames.Spacesareallowed.Youcanuseunderscoreswithinthechannel,task,orscalename,butyoucannotuseleadingunderscores,suchas_Dev1.

Youmustusenomorethan256characters.

SpecialConsiderationswithLabVIEWProjectIntheDAQAssistant,youreceiveawarningdialogifyouattempttonameaLabVIEWProjectchannelthesamenameasanexistingMAXglobalvirtualchannel.TheDAQAssistantforcesyoutochooseauniquename.However,inLabVIEWProject,youcanright-clickachannelandrenameittothesamenameasaMAXglobalvirtualchannel.IfyoudorenamethechanneltothesamenameasaMAXchannel,thenexttimeyouusetheDAQAssistant,oranI/OControl,theMAXchannelwillbegrayedoutandyoucannotselectit.

EditingaTaskorGlobalVirtualChannelYoucanusetasksandglobalvirtualchannelsinyourNIapplicationsoftwareorinMAX.

LabVIEWCompletethefollowingstepstoeditataskorglobalvirtualchannelsavedinMAX:

1. PlaceeitheraDAQmxTaskNamecontroloraDAQmxGlobalChannelcontrolonthefrontpanel.

2. Selectthetaskorglobalvirtualchannelfromthepull-downlist.3. Right-clickthecontrolandselectEditDAQmxTaskorEdit

DAQmxChannel.Then,selectthedestination.4. ModifythetaskorglobalvirtualchannelwhentheDAQAssistant

launches.5. ClickOKtosavethechanges.

LabVIEWSignalExpressWithLabVIEWSignalExpress2.5andlater,youcanimporttasksfromMAXandcopyglobalvirtualchannelsfromMAXintoDAQsteps.IfyouimportataskfromMAX,thetaskbecomeslocaltothatLabVIEWSignalExpressproject,andyoucannotsaveitbacktoMAX.Also,anyglobalvirtualchannelscontainedinthetaskbecomelocalvirtualchannels.Then,youcanusethechannelsinyourLabVIEWSignalExpressapplication.

LabWindows/CVIYoumustuseMAXtoeditglobalvirtualchannels.Toeditatask,selectTools»Create/EditDAQmxTasksandchoosethetaskyouwanttoedit.YoualsocaneditMAX-basedtaskswithinMAXbyselectingDataNeighborhood»NI-DAQmxTasksandchoosingthetaskyouwanttoedit.

MeasurementStudioYoumustuseMAXtoeditglobalvirtualchannelsorMAX-basedtasks.

Toeditaproject-basedtask,gototheprojectanddouble-clickthe.mxbfiletolaunchtheDAQAssistant.

MAXToeditataskorglobalvirtualchannelusingtheDAQAssistantfromwithinMAX,completethefollowingsteps:

1. ExpandDataNeighborhood.2. ExpandNI-DAQmxTasksorNI-DAQmxGlobalVirtual

Channels.3. Clickthetaskorglobalvirtualchannelyouwanttoedit.4. ModifythetaskorglobalvirtualchannelintheDAQAssistant.5. ClickSavewhenyouarefinished.

NoteIfanasteriskappearsnexttoaglobalvirtualchannel,thechannelhasunsavedchanges.

AddingVirtualChannelstoTasksYoucanaddvirtualchannelstoyourtask.Additionalvirtualchannelsmustbeofthesameclass,suchasanaloginputoranalogoutput,asthetask.Toaddvirtualchannelstoyourtask,completethefollowingsteps:

1. ClicktheAddbutton.2. Fromthedrop-downlist,selectthemeasurementtypetoadd.3. Adialogboxpromptsyoutoselectaphysicalchannelfromalist

ofvalidphysicalchannel(s)forthatmeasurementtype.Selectthephysicalchannelstoaddtoyourtask.Alternatively,youcanaddexistingglobalvirtualchannelsorcopyinformationfromanexistingglobalvirtualchanneltoalocalvirtualchannel.

4. ClickOK.5. Repeatthesestepstoaddmorevirtualchannels.

CreatingandEditingScalesYoucanusetheDAQAssistanttocreateandeditscalesforyourtasksandglobalvirtualchannels.YoucanuseanNI-DAQmxScaletospecifyaconversionfromtheprescaledunitsmeasuredbyaphysicalchanneltothescaledunitsassociatedwithyourtransduceroractuator.Youcanthenassociatethisscalewithoneormorevirtualchannels.Often,youdonotneedtocreateanNI-DAQmxScale,becauseNI-DAQmxhasexplicitsupportforthemostcommontransducersandactuators.Forexample,whencreatingananaloginputtemperaturevirtualchannel,youcanspecifywhichtypeoftransducer(suchasathermistor,RTD,orthermocouple)isusedtomakethemeasurement.However,ifNI-DAQmxdoesnotexplicitlysupportyourtransduceroractuator,youcancreateanNI-DAQmxScalethatspecifieshowtoconvertfromtheprescaledunitstothescaledunits.NoticethatthesameNI-DAQmxScalecanbeassociatedwithmultiplevirtualchannels.YoudonotneedtocreateanNI-DAQmxScaleforeachvirtualchannelifthescaleisthesame.

CreatingScalesFollowthesestepstocreatenewscales:

1. Youcancreateanewscaleinthefollowingways:DAQAssistant—ClicktheScaleiconandselectCreateNew.MAX—Right-clickScalesintheconfigurationtree,andselectNewScale.IntheCreateNewwindow,selectNI-DAQmxScale.LabVIEW—PlacetheDAQmxScaleNamecontrolonthefrontpanel.Right-clickthecontrolandselectNewScale(DAQAssistant).

2. WhentheCreateScalewizardlaunches,selectthescaletypeandclickNext.

3. Enteranameforyourscale.4. ClickFinishtocontinueconfiguringyourscaleintheDAQ

Assistant.5. ClickOKorSaveScaletosaveyourscaletoMAX.

EditingScalesLabVIEW—Completethefollowingstepstoeditapreviouslysavedcustomscale:

1. PlaceaDAQmxScaleNamecontrolontheblockdiagram.2. Selectacustomscaleyoupreviouslycreatedandsaved.3. Right-clickthecontrolandchooseEditScale(DAQAssistant).4. ModifythescaleintheDAQAssistant.5. ClickOKtosavethechanges.

MAX—Completethefollowingstepstoeditapreviouslysavedcustomscale:

1. ExpandScales.2. Clickthescaleyouwanttoedit.3. ModifythescaleintheDAQAssistant.4. ClickSaveScalewhenyouarefinished.

TestingYourConfigurationClickRuntotestyourconfigurationandmakesureyoursensorsandsignalsareconnectedproperly.Dataacquiredappearsinthepreviewview.Verifythatyouareacquiringtheexpecteddataandthatyouconnectedthesignalproperly.Ifnecessary,modifyanysettingsandclickRuntotestyourconfigurationagain.

SavingYourConfigurationYoucansaveyourtaskorglobalvirtualchannelconfigurationtoMAXinseveralways,dependingonhowyoulaunchedtheDAQAssistant.Tosaveyourconfiguration,dothefollowing:

MAX—ClickSaveonthetoolbar.YoualsocancheckforerrorsinyourtaskbyclickingSave.Ifyourtaskhasanerror,adialogboxappears.ClickNointhedialogboxtocancelthesaveandshowtheerror(s).LabVIEW—ClickOK.

NoteIfyouconfigureataskusingtheDAQAssistantExpressVI,thetaskislocaltotheapplicationandcannotbesavedtoMAXforuseinotherapplications.YoumustconverttheDAQAssistantExpressVItoanNI-DAQmxTasktosavethetasktoMAXforuseinotherapplicationsortogeneratecode.

LabWindows/CVI—ClickOK.MeasurementStudio—SelectFile»Save.

YoucanaccesssavedglobalvirtualchannelsandtasksinDataNeighborhoodinMAXorinyourNIapplicationsoftware.

NoteYoucannotsaveaglobalvirtualchanneloratasktoMAXwithLabVIEWSignalExpress.

UsingYourTaskorGlobalVirtualChannelinYourApplicationSoftwareYoucanusetasksorglobalvirtualchannelssavedinMAXwhenprogrammingyourapplications.IfyouareusingLabVIEW7.xorlater,LabWindows/CVI7.xorlater,orMeasurementStudio7.xorlater,youcangeneratecodefromyourtaskorglobalvirtualchannelforuseinyourapplication.RefertoLabVIEWHelp,LabWindows/CVIHelp,MeasurementStudioHelp,orNI-DAQmxHelpformoreinformationaboutprogrammingwithyourtaskorglobalvirtualchannel.RefertoLabVIEWSignalExpressHelpforinformationaboutusingtheDAQAssistantinLabVIEWSignalExpress.

NoteYoucanaccessglobalvirtualchannelsinLabWindows/CVIandMeasurementStudioonlyifyouareaddingthemtoatask.

LabVIEWCompletethefollowingstepstoaccessyourtaskorglobalvirtualchannel:

1. PlaceeithertheDAQmxTaskNamecontrolortheDAQmxGlobalChannelcontrolonthefrontpanel.

2. Clickthepull-downmenuandselectthetaskorglobalvirtualchannel(s)youwanttouseinyourapplication.Youcanselectmultipleglobalvirtualchannels,butnotmultipletasks.YoualsocanselectBrowsetofindtasksandglobalvirtualchannels.

LabVIEWSignalExpressToaccessataskyoucreatedinMAX,selectTools»ImportTaskfromMAXinLabVIEWSignalExpress2.5andlater.

NoteAnyglobalvirtualchannelsinthetaskyouimportbecomelocalvirtualchannelsinLabVIEWSignalExpress.

YoualsocancopyglobalvirtualchannelsintoyourDAQstepsinLabVIEWSignalExpresswhenyouareaddingchannelstothestep.

1. SelecttheVirtualtab.TheVirtualtabappearsonlyifyouhavealreadycreatedaglobalvirtualchannelofthesamemeasurementtypeasyourstep.

2. Selecttheglobalvirtualchannelyouwanttocopytothestep.Whenyoucopytheglobalvirtualchanneltoyourstep,itbecomesalocalvirtualchannel.

LabWindows/CVICompletethefollowingstepstoaccessyourtask:

1. OpentheDAQmxLoadTaskfunctionpanel.2. Press<Enter>intheTaskNamecontrol.Alistoftasknamesyou

canuseappearsinthecontextmenu.3. Selectthetaskyouwanttousefromthecontextmenu.

MeasurementStudioLaunchoneofthefollowingwizardsfromtheProject»AddNewItemmenu:

TouseataskstoredinMAXtocreateanewproject-basedtask,usetheDAQmxTaskAddNewItemwizard.ToreferenceataskstoredinMAXwhencreatingaVisualC++DAQmxUserCode,usetheDAQmxUserCodeAddNewItemwizard.ToreferenceataskstoredinMAXwhencreatinga.NETDAQmxUserControl,usetheDAQmxUserControlAddNewItemwizard.

EachofthesewizardsopensadialogboxyoucanusetoselectatasksavedinMAX.

ConvertingtheDAQAssistantExpressVItoanNI-DAQmxTaskWhenyouconfigureataskusingtheDAQAssistantExpressVI,thetaskislocaltotheapplicationandcannotbeusedinotherapplications.YoucanconvertaDAQAssistantExpressVItoanNI-DAQmxTaskifyouwanttosavethetasktoMAXforuseinotherapplicationsortogeneratecode.

NoteIfyouareworkingwithinaprojectinLabVIEW,convertingtheDAQAssistantExpressVItoatasksavesthetasktotheproject.

CompletethefollowingstepstoconverttheDAQAssistantExpressVItoanNI-DAQmxTask.

1. Right-clicktheDAQAssistantExpressVIandselectConverttoNI-DAQmxTaskfromtheshortcutmenu.

2. TheDAQAssistantlaunches,andyoucanmodifythetask,ifnecessary.

3. ClicktheOKbutton.4. AnNI-DAQmxTaskreplacestheDAQAssistantExpressVI.

CalibratingChannelsUsetheChannelCalibrationWizardtoaddsoftwarechannelcalibrationtoavirtualchannel.Channelcalibrationtakessensors,hardware,andmeasurementsoftwareintoaccountandappliescompensationtothemeasurementinadditiontoallscalingandhardwarecalibration,thusimprovingmeasurementaccuracy.CompletethefollowingstepstolaunchtheChannelCalibrationWizardfromtheDAQAssistantandcalibrateanaloginputvirtualchannels.

1. Selectanexistingtaskorglobalchannelorcreateanewtaskorglobalchannel.

2. ClicktheCalibrationtabintheDAQAssistant.3. SelectoneormorevirtualchannelsfromtheChannelList.You

mustselectonlyonetypeofvirtualchannel.Ifyouselectvirtualchannelsofdifferentmeasurementtypes,theCalibratebuttonisdisabled.

4. ClickCalibrate.TheChannelCalibrationWizardlaunches.Completethescreenstocalibratetheselectedvirtualchannel.Youcancalibrateasmanydatapointsasneededtoproduceacalibrationtable.TheChannelCalibrationWizardstoresasetofcalibrationpropertiesforeachvirtualchannelyoucalibrate.SelectPropertiesintheCalibrationtaboftheDAQAssistanttoviewcalibrationhistory,verifythecalibration,recalibratetheselectedvirtualchannel(s),andgenerateacalibrationreport.Ifyouselectvirtualchannelsofdifferentmeasurementtypes,thePropertiesbuttonisdisabled.Aftercalibratingthevirtualchannel,clickEnableCalibrationtoenableordisablethecalibration.IfEnableCalibrationisdisabled,thecalibrationissavedbutnotappliedtotheselectedvirtualchannels.Todeleteacalibration,selectoneormorevirtualchannelsintheChannelListandclickDeleteCalibration.IntheCalibrationtab,theCalibrationDateandExpirationDateshowwhenthelastcalibrationoccurredandwhenthecalibrationexpires.Iftheseindicatorsaredisabled,youhaveselectedvirtualchannelsthathavedifferentcalibrationand/orexpirationdatesorarenotcalibrated.

GeneratingCodeIfyouareusingNIapplicationsoftwareversion7.xorlater,youcangeneratecodeforuseinyourapplications.YoucangeneratecodeinLabVIEW7.xorlater,LabVIEWSignalExpress2.xorlater,LabWindows/CVI7.xorlater,andMeasurementStudio7.xorlaterfromanytasksavedinMAX.YoualsocangeneratecodefromaglobalvirtualchannelinLabVIEW7.xorlater.AnychangesyoumaketothegeneratedcodeapplyonlytothetaskintheapplicationandarenotsavedbackintothetaskorglobalvirtualchannelintheDAQAssistant.

TypesofCodeGenerationTherearethreeoptionsforgeneratingcodeinyourNIapplicationsoftwarefromataskorglobalvirtualchannel:

Example—Generatesallthecodenecessarytorunthetaskorglobalvirtualchannel,suchasVIsneededtoreadorwritesamples,VIstostartandstopthetask,loops,andgraphs.Choosethisoptionifyouwanttorunthetaskorglobalvirtualchannelyoucreatedtoverifythatitworksortouseyourconfigurationinasimpleapplication.ThegeneratedcodeisasimpleNI-DAQmxexamplethatyoucanthenmodifyforyourapplication.Configuration—Generatesthecodethatreplicatestheconfigurationofthetasksandglobalvirtualchannels.Choosethisoptionifyouwanttodeployyourapplicationtoanothersystem.RefertoDeploymentintheNI-DAQmxHelplocatedatStart»AllPrograms»NationalInstrumentsformoreinformation.

WhenyougenerateConfigurationcode,thelinkbetweentheapplicationandtheDAQAssistantislost.AnychangesyoumaketotheconfigurationcodearenotreflectedintheDAQAssistant.YoucanregenerateConfigurationcodefromtheDAQAssistant,buttheregeneratedcodedoesnotmaintainpreviouschangesthatyoumadetothecode.

CautionAlthoughgeneratedconfigurationcodeincludescodetocreateglobalvirtualchannelsandtasks,itdoesnotincludecodetocreatescales.Ifyougenerateconfigurationcodefordeploymentofapplicationsthatincludescales,youmustensurethatthescalesareconfiguredinthetargetcomputer.RefertoDeploymentintheNI-DAQmxHelpfordeploymentoptions.

ConfigurationandExample—YoumustuseLabVIEWtogeneratethistypeofcode.Choosethisoptionifyouwanttocreateaportable,completeapplicationthatcanrunonothersystems.NoteIfyouright-clicktheDAQAssistantExpressVIandselectGenerateNI-DAQmxCode,yougeneratebothconfigurationandexamplecode.

GeneratingCodeinYourApplicationSoftwareSelectyourNIapplicationsoftwareformoreinformationonthetypesofcodeyoucangenerateandhowtousetheDAQAssistanttogeneratecode.

LabVIEWLabVIEWSignalExpressLabWindows/CVIMeasurementStudio

GeneratingCodeinLabVIEWThissectiondescribeswhathappensduringcodegenerationinLabVIEWandhowtogeneratecodeusingtheDAQAssistant.

TypesofCodeGenerationYoucangenerateallthreetypesofcodeinLabVIEW.Forgeneralinformationaboutthetypesofcodeandspecialconsiderations,refertoGeneratingCode.

Example—ThisoptionaddstotheVIyouareworkingin.Configuration—TheI/Oconstant/controlisreplacedwithasubVIthatcontainsVIsandpropertynodesusedforphysicalchannelcreationandconfiguration,timingconfiguration,andtriggeringconfigurationusedinthetaskorglobalvirtualchannel.


ConfigurationandExample—ThisoptiongeneratesbothConfigurationcodeandExamplecodeforthetaskorglobalvirtualchannelinonestep.

GeneratingCodeinLabVIEWCompletethefollowingstepstogeneratecode:

1. PlaceeithertheDAQmxTaskNamecontrolorDAQmxGlobalChannelcontrolonthefrontpanel.

2. Clickthepull-downmenuandselectthetaskorglobalvirtualchannelfromthelist.

3. Right-clickthecontrolandselectGenerateCode»Example,Configuration,orConfigurationandExample.

GeneratingCodeinLabVIEWUsingtheDAQAssistantExpressVIIfyouconfigureataskusingtheDAQAssistantExpressVI,youcanright-clicktheVIandselectGenerateNI-DAQmxCodetogenerateconfigurationandexamplecode.ThecodereplacestheDAQAssistantExpressVI.

NoteWhenyouconfigureataskusingtheDAQAssistantExpressVI,thetaskislocaltotheapplicationandcannotbesavedtoMAXforuseinotherapplications.YoucanconverttheDAQAssistantExpressVItoanNI-DAQmxTasktosavethetasktoMAXforuseinotherapplications.

GeneratingCodeinLabVIEWSignalExpressAfteryoucreateandsaveaprojectinLabVIEWSignalExpress,youcangenerateLabVIEWcodefromLabVIEWSignalExpress.RefertotheLabVIEWSignalExpressHelpforinstructionsonhowtogenerateVIsfromaLabVIEWSignalExpressproject.IfyouhaveDAQstepsinyourLabVIEWSignalExpressproject,thosestepsareconvertedtoDAQAssistantExpressVIsinLabVIEW.However,inthefollowingsituations,LabVIEWSignalExpresscreatesatop-levelExpressVIforyourentireproject:

YouhavesynchronizedDAQstepsbysharingtriggeringortimingsignalsbetweentheminoneproject.AnyDAQstepcontainsmorethanonemeasurementtype,suchasvoltageandtemperature.DAQstepsareanalogoutputordigitaloutput.YouhaveconfiguredexecutiondelaysbetweenyourDAQsteps.

Inthesecases,youmustdouble-clickthetop-levelexpressVItoopenLabVIEWSignalExpresstochangetheprojectsettings.

GeneratingCodeinLabWindows/CVIThissectiondescribeswhathappensduringcodegenerationinLabWindows/CVIandhowtogeneratecodeusingtheDAQAssistant.

TypesofCodeGenerationYoucangeneratetwotypesofcodeinLabWindows/CVI.Forgeneralinformationaboutthetypesofcodeandspecialconsiderations,refertoGeneratingCode.

Example—Thisoptioncreatesafunctionthathasthetaskandaddsthesourcefilestotheproject.Configuration—TheDAQmxLoadTaskfunctionisreplacedwithacalltoaDAQAssistant-generatedfunctionthatbuildsthetaskprogrammatically.


GeneratingCodeinLabWindows/CVITogenerateexamplecodeinLabWindows/CVI,completethefollowingsteps:

1. Right-clickacalltoDAQmxLoadTaskinasourcefile.2. SelectGenerateDAQExampleCode.3. Specifythenameofthefunctionthatrunsyourtaskandthefileto

containthegeneratedexamplecode.4. ClickOK.

Thegeneratedcodeincludessourceandheaderfilesthatdefinetheruntaskfunction.LabWindows/CVIautomaticallyaddsthesefilestotheprojectandmodifiesthecurrentsourcefiletocalltheruntaskfunction.Whencalled,theruntaskfunctionprogrammaticallycreatesauserinterfacepanelthatallowsyoutostartthetaskanddisplaythedata.Togenerateconfigurationcode,youcanstoreataskinyourproject,whichcausestheDAQAssistanttogeneratesourcecodetocreatethespecifiedtaskprogrammatically.Thegeneratedsourceandheaderfiledefineanentrypointfunctionthatconfiguresthetaskandreturnsataskhandle.Ageneratedbinaryfile(.mxb)containsabinarydescriptionofthetaskthatisusedwheneditingthetaskintheDAQAssistant.TheDAQAssistantaddsallthreefilestotheprojectwhenyoucreateaproject-basedtask.YoucanconvertaMAX-basedtasktoaproject-basedtaskbyright-clickingDAQmxLoadTaskinasourcefileandselectingCopyDAQTaskToProjectfromthecontextmenu.Thisoptionperformsthefollowingactions:

GeneratesandaddsfilestotheprojectReplacesDAQmxLoadTaskwithacalltothegeneratedentrypointfunctionAddsanincludestatementforthegeneratedheaderfile

GeneratingCodeinMeasurementStudioThissectiondescribeswhathappensduringcodegenerationinMeasurementStudioandhowtogeneratecodeusingtheDAQAssistant.

TypesofCodeGenerationYoucangeneratetwotypesofcodeinMeasurementStudio.Forgeneralinformationaboutthetypesofcodeandspecialconsiderations,refertoGeneratingCode.

Example—Thisoptioncreatesafunctionthathasthetaskandaddsthesourcefilestotheproject.Configuration—TheDAQmxLoadTaskfunctionisreplacedwithacalltoaDAQAssistant-generatedfunctionthatbuildsthetaskprogrammatically.


GeneratingCodeinMeasurementStudioAfteryouconfigureandsaveatask,aclassisgeneratedandaddedtotheproject.Theclasscontainsthesourcecodethatcorrespondstotheconfigurationinformationthatisstoredinthe.mxbfile.

NoteWhenyouusetheDAQAssistantconfigurationeditortomakechangestotheDAQmxtaskclass,the.mxbfileissavedandthetaskcodeisregenerated.Ifyoumakechangesdirectlytothegeneratedsourcecodefile,thosechangesarelostwhenthesourcecodeforthe.mxbfileisregenerated.ToenhanceorextendthecodethattheDAQAssistantgenerates,youcancopythesourcecodefile,changethenameoftheDAQmxtaskclass,andaddthecopiedfiletotheproject.Thecopiedfileisnotassociatedwitha.mxbfile.Asaresult,theDAQAssistantdoesnotoverwritethesourcecodefile.

GeneratingCodefora.NETDAQmxTaskClassTheDAQmxtaskclasscodeiscontainedinahidden.csor.vbsourcecodefileintheproject.Thissourcecodefilehasthesamebasenameasthe.mxbfile,buthasanextensionthatcorrespondstothelanguageofthesourcecode.Completethefollowingstepstoviewthehidden.csor.vbfile:

1. SelectShowAllFilesintheSolutionExplorertoolbar.2. IntheSolutionExplorer,expandthe.mxbfilenode.3. Right-clickthe.csor.vbfileandselectViewCodetoviewthe

code.

Togeneratethesourcecode,the.mxbfilehasaCustomToolpropertythatassociatestheDAQAssistantwiththe.mxbfile.

TipYoucanviewthepropertysettingsforthe.mxbfile.SelectthefileintheSolutionExplorerandviewitspropertiesinthePropertiesWindow(View»PropertiesWindow).

GeneratingCodeforaVisualC++DAQmxTaskClassTheDAQmxtaskclasscodeiscontainedina.hand.cppfileintheproject.Thesefileshavethesamebasenameasthe.mxbfile,buthavedifferentextensionsfortheheaderandsourcefiles.

TheMeasurementStudioAdd-Inmonitorsallchangestothe.mxbfile.Whenan.mxbfilethatiscontainedinaVisualC++projectissaved,theadd-incausestheDAQAssistanttogeneratethesourcecodefortheconfigurationthatisstoredinthe.mxbfile.

RefertotheNIMeasurementStudioHelpformoreinformationaboutgeneratingcodeandusingataskinMeasurementStudio.

GeneratingDiagramsandReportsIntheDAQAssistant,youcanusetheConnectionDiagramtooltodisplayeitheratextoranHTMLfileoftheconnectionsfromeachsensortotheconnectorblocks.YoucanalsousetheMAXReportWizardtogenerateareportoftheNI-DAQmxhardwareandsoftwareconfigurationofthesystem.

ConnectionDiagramsTheConnectionDiagramtoolintheDAQAssistantcancreateeithertextorHTMLreportsoftheconnectionsfromeachsensortotheconnectorblock.

ViewingConnectionDiagramsToviewaconnectiondiagramfromwithintheDAQAssistant,clickConnectionDiagram.Selecteachvirtualchannelinthetasktoviewconnectionsfromsensortoconnectorblock.Theconnectionslistdisplayseachoftheconnectionsintextformat,specifyingterminalnamesandnumbers.UsetheSaveasHTMLoptionintheConnectionDiagramtooltogenerateanHTMLreportofyourtask.Thereportcontainsthefollowingitems:

ListofvirtualchannelsinthetaskPhysicalchannelsDevicetypesMeasurementtypesConnectiondiagrams

Tosaveaconnectiondiagram,clickSaveasHTMLandenteranamefortheHTMLfile.Animagessubdirectoryiscreatedthatcontainsalloftheconnectiondiagramimages.UseawebbrowsersuchasMicrosoftInternetExplorertodisplayandprinttheHTMLreport.

ConnectionDiagramSupportThetoolcurrentlysupportsanaloginputmeasurementtypesandthefollowingMIOandSCXIscrewterminalblocks:

CB-11CB-27CB-37FHCB-37FVCB-50CB-68LPCB-68LPRCB-C68DAQPad-6015/6016PXI-4204PXI-4220SCB-100SCB-68SCXI-1300,1303,1304,1308,1313,1314,1314T,1315,1317,1320,1321,1322,1327,1328,1338TB-2705TB-2706TB-2725TBX-68

MAXReportGenerationInadditiontotheConnectionDiagramtoolintheDAQAssistant,youcanusetheMAXReportWizardtogenerateareportoftheNI-DAQmxhardwareandsoftwareconfigurationofthesystem.Thereportincludesthefollowing:

Realandsimulateddeviceinformation,includingdevicename,devicetype,serialnumber,connectedaccessory,andothersettingsTaskinformation,includingchannels,timing,triggering,andotherpropertysettingsGlobalchannelpropertysettingsCustomscalepropertysettings

TheMAXReportWizardsupportsbothlocalandremotesystems.

GeneratingCurrentorVoltageYoucangeneratetwomainkindsofsignalsforchannels:

Singlesamples,includingDCsignals—Whengeneratingsinglesamples,youcanusesoftwareorhardwaretiming(ifavailable)tocontrolwhenyourdevicegeneratesasignal.Multiplesamples—UsemultiplesamplestogenerateanACsignal,suchasasinewave.Alsocalledbufferedanalogoutput,generatingmultiplesamplesinvolvesthefollowingsteps:

1. Yourapplicationwritesmultiplesamplesintoabuffer.2. Allthesamplesinthebufferarethensenttoyourdevice

accordingtothetimingyouspecify.Youcanusesoftwareorhardwaretiming(ifyourdevicesupportshardwaretiming)tocontrolwhenyourdevicegeneratesasignal.

NoteSomecurrentgenerationdevices,suchastheSCXI-1124,allowyoutouseeitheraninternalorexternalcurrentsupply.Thechoiceofsupplyisdeterminedbytheterminalconnectionsusedtoconnecttheloadtothedevice.Ifyouplantouseaninternalsupply,connecttheloadtotheterminalsSUPPLYandISINK.Ifyouplantouseanexternalsupply,jointhesupplyandloadtoISINKandGND.Itisimportanttoverifythattheterminalconnectionsarecorrect.Inadditiontoproperconnections,verifythattheattachedloaddoesnotexceedthecapabilitiesofthedevice.Refertoyourdevicedocumentationformoreinformation.

Clickhereformoreinformationaboutgeneratingvoltage.Clickhereformoreinformationaboutgeneratingcurrent.

MeasuringAccelerationwithanAccelerometerAccelerationisachangeinvelocitywithrespecttotime.Accelerometersaretransducersthatrepresentaccelerationasavoltage.Theyarespecifiedbytherange,frequencyresponse,andthesensitivityofthedevice.Accelerometerscomeintwoaxialtypes.Themostcommonaccelerometermeasuresaccelerationalongonlyasingleaxis.Thesecondtypeisatri-axialaccelerometer,whichcancreatea3Dvectorofacceleration.Bothtypesofaccelerometercanbeeitherpassiveoractivesensors.Bothtypesalsocomewitheitherbothleadsinsulatedfromthecase(isolated)orwithoneleadgroundedtothecase.Tomeasureaccelerationwithapassivesensor,thesensormustbeconnectedtoacharge-sensitiveamplifier.Theactiveaccelerometerisnearlyidenticaltothepassiveaccelerometer,withtheadditionofacharge-sensitiveamplifierbuiltinsidetheaccelerometer.Thecurrentsourceprovidestheexcitationforthebuilt-inamplifierofthesensor,whiletheinstrumentationamplifiermeasuresthevoltagepotentialacrosstheleadsofthesensor.SomeanaloginputdevicessupportprogrammableACorDCcoupling.Ifyourdevicesupportsthisfeature,youraccelerationmeasurementtaskiscreatedusingACcoupling.Ifyoudesireadifferentcouplingbehavior,youcanchangethispropertyprogrammatically.

MeasuringAnalogFrequencyTomeasurethefrequencyofanACsignal,youneedcircuitrythatproducestriggersofthesamefrequencyasthemeasuredsignal.TheparametersthatdeterminewhentotriggerareThresholdLevelandHysteresis.Everytimethesignalpassesfrom(ThresholdLevel–Hysteresis)toThresholdLevel,atriggeroccurs.

Note(ThresholdLevel–Hysteresis)mustbebetween–0.5and4.48fortheSCXI-1126module.

Apulsegeneratorusesthesetriggersandproducesapulseonceeveryfrequencycycle.Thewidthofthispulseissetbytheinputfrequencyrange.Astheinputfrequencyrangeincreases,thepulsewidthgrowssmaller.ThispulsetrainisthenconvertedtoaDCsignalthathasalevelproportionaltothedutycycleofthepulsetrain.Thedutycycleisthefractionofaperiodofthepulsetrainwhenthepulseisoccurring.TheDCsignalhasavoltagethatisproportionaltotheinputfrequencyandcanthereforebescaledtothatfrequencyvalue.

MeasuringAngularDisplacementwithanRVDTAngulardisplacementismovementaboutanaxis,suchastheangularmotionoftheshaftofamotor.Anangulardisplacementsensorisadevicewhoseoutputsignalrepresentstherotationoftheshaft;itcannotmeasurethephysicaldisplacementofthewholeshaft.Onetypeofsensorthatmeasuresangulardisplacementisarotaryvariabledifferentialtransformer(RVDT).RVDTsaretherotationalversionofLVDTsandgenerallyoperateoverarangeof±30°–70°.Theyareavailableinservo-mountandcanrotatethrough360°withoutencounteringastop.RVDTsrequirespecialelectronicsdesignedforthesensor.RVDTstypicallyhaveadelayof10mscausedbyrequiredfilteringinthesignalconditioner.Theyareextremelyruggedandoperateoverwidetemperatureranges.Inenvironmentscharacterizedbyextremesintemperatureandshock,anRVDTistheclearchoiceforrotationalapplicationswhenyouneedmorethan70°ofmeasurementrange.

MeasuringCurrentMostmeasurementdevicescanmeasurevoltageswithinacertainrange.Witharesistor,youalsocanmeasurethecurrentthroughananaloginputconnector.Todoso,youmustplaceaknownresistanceinparallelwiththeinputconnectorandcurrentsource.YoucanmeasurevoltagedroppedacrosstheresistorandconvertittocurrentusingOhm'sLaw:I(A)=V(V)/R(Ω)

whereIisthecurrent,Visthevoltage,andRistheresistance.Measuringcurrentiscommonbecausemanydevicesgeneratea4–20mAcurrenttorepresentaphysicalquantity.Forinstance,youcanusecurrenttomeasurethelevelinatank.Usingalevelsensor,4mAcouldrepresentanemptytank,and20mAcouldrepresentafulltank.

MeasuringCustomVoltagewithExcitationThismeasurementtypeallowsyoutousesensorsthatarenotexplicitlysupportedbyNI-DAQmxandrequirevoltageexcitation,suchasbridgesensors,loadcells,andpressuretransducers.Typically,youusethismeasurementtypewithSCXImodulesthatincludeanexcitationsourceandconfigureacustomscaletoconvertthevoltagethesensorreturnstotheunitsyouwanttomeasure.ForsensorsthatarenotexplicitlysupportedbyNI-DAQmxanddonotrequireanyexcitation,usethevoltagemeasurementtypewithacustomscale.ForsensorsthatarenotsupportedbyNI-DAQmxandrequirecurrentexcitation,usethevoltagemeasurementtypewithacustomscale,andusetheAIexcitationDAQmxChannelpropertiestoconfiguretheexcitation.

MeasuringLinearDisplacementwithanLVDTLineardisplacementismovementinonedirectionalongasingleaxis.Thelinearvariabledifferentialtransformer(LVDT)isasensorthatmeasureslineardisplacement.LVDTsoperateontheprincipleofatransformerandconsistofastationarycoilassemblyandmoveablecore.AnLVDTmeasuresdisplacementbyassociatingaspecificsignalvalueforanygivenpositionofthecore.LVDTsignalconditionersgenerateasinewavefortheprimaryoutputsignalandsynchronouslydemodulatethesecondaryoutputsignal.Thedemodulatedoutputispassedthroughalowpassfiltertoremovehigh-frequencyripple.TheresultingoutputisaDCvoltageproportionaltocoredisplacement.ThesignoftheDCvoltageindicateswhetherthedisplacementistotheleftorright.LVDTstypicallycomein4-wire(openwire)and5-wire(ratiometricwire)configurations.WiresfromthesensorconnecttoasignalconditioningcircuitthattranslatestheoutputoftheLVDTtoameasurablevoltage.Themethodofsignalconditioninguseddifferentiatesthe4-wireand5-wireconfigurations.

MeasuringResistanceResistanceistheoppositiontopassageofanelectriccurrent.Oneohmistheresistancethroughwhich1Vofelectricforcecausesoneamperetoflow.Twocommonmethodsformeasuringresistancearethe2-wiremethodandthe4-wiremethod.Forbothmethods,acurrentissentthrougharesistorwithameasurementdevicemeasuringthevoltagedropfromthesignalacrosstheresistor.The2-wiremethodiseasiertoimplement,butisnotasaccurateforresistancesbelow100Ω.Tocalculateresistance,usethefollowingformula:R=V/I

whereR=resistance,V=voltage,andI=current.

MeasuringSoundPressureSoundpressureisthedynamicvariationofthestaticpressureofairandismeasuredinforceperunitarea(Pa).Theinstantaneoussoundpressureistypicallyaveragedoveracertaindurationtogivesoundpressurelevel.Soundpressurelevelisnormallyrepresentedonalogarithmicamplitudescale,whichissimilartothehumanperceptionofhearing.Typicalvaluesonthislogarithmicscaleareasoundlevelof0dB,whichistheaveragethresholdofhumanhearing,60to70dBfornormalconversation,110dBatanextremelyloudconcert,and150dBforthenoiseofarockettakeofforajetengineatcloserange.TheSoundPressureLevel(SPLorLP)indecibelsisdefinedasthefollowing:SPL=20log10(p/pref)wherepistheinstantaneoussoundpressureinPaandprefis20µPa,theinternationallyacceptedreferenceforsoundpressuremeasurements,whichroughlycorrespondstothethresholdofhumanhearing.Youcanuseamicrophonetomeasuresoundpressure.Themicrophoneactsasatransducer,creatingavoltagesignalthatisproportionaltotheinstantaneoussoundpressure.SomeanaloginputdevicessupportprogrammableACorDCcoupling.Ifyourdevicesupportsthisfeature,yoursoundpressuremeasurementtaskdefaultstoACcoupling.Ifyouwantadifferentcouplingbehavior,youcanchangethispropertyprogrammatically.

MeasuringStrainwithaStrainGageStrainistheamountofdeformationofabodyduetoanappliedforce.Specifically,strainisdefinedasthefractionalchangeinlength.Straincanbepositive(tensile)ornegative(compressive).Inpractice,themagnitudeofmeasuredstrainisverysmall.Therefore,strainisoftenexpressedasmicrostrain(µε).Whenabarisstrainedwithauniaxialforce,PoissonStraincausesthegirthofthebartocontractinthetransverse,orperpendicular,direction.ThemagnitudeofthistransversecontractionisamaterialpropertyindicatedbyitsPoisson'sRatio.Tomeasurestrain,youtypicallyuseoneormorestraingagesinaWheatstonebridgeinoneofseveralbridgeconfigurations.

UsingtheStrainGageCalibrationWizardWhenyouconfigureastrainmeasurementtask,youcanusetheStrainGageCalibrationWizardtocalibrateyourstraingage.Completethefollowingstepstocalibratethestraingage:

1. ClickCalibratetolaunchtheStrainGageCalibrationWizard.2. FollowthestepsontheSetupHardwarewindow.Youcan

configurethefollowingsettings:EnableOffsetNullingEnableShuntCalibration

3. ClickNext.4. UsetheMeasureandCalibratewindowtomeasureandcalibrate

yourstraingage.Thesoftwareautomaticallytakesthefirstmeasurement,andthetabledisplaystheresults.Thetableshowsthefollowinginformation:ChannelInformationOffsetAdjustment—Thissectionshowsinformationabouttheoffseterrortohelpyoudetermineifyoushouldperformanoffsetnullcalibration.Performanoffsetnullcalibrationifyouperformashuntcalibration.GainAdjustment—Thissectionshowsvaluesrelatedtogainerrorandtheshuntcalibrationprocedure:

5. Performyourmeasurementandcalibrationwiththefollowingbuttons:

ClickMeasuretomakeapreliminarymeasurementusingtheoffsetandshuntcalibrationdatafromapreviouslyrunstraingageprocedure.ClickResetDatatoresettheoffsetandshuntcalibrationdataandmakeameasurementusingtheirdefaultvalues.ClickCalibratetoperformtheoffsetand/orshuntcalibration.Thetableshowstheresultingmeasurements.

6. ClickFinishwhenyouaredone.Thecalibrationdataissavedaspartofyourvirtualchannel.Onsuccessfulcompletion,thesoftwareautomaticallyusesthecalibrationdatawhenscaling

voltagetostrainsonthisvirtualchannel.NoteIfyouareusinganSCXI-1520withanSCXI-1314terminalblock,PXI-4220,SCXI-1121withanSCXI-1321terminalblock,oranSCXI-1122withanSCXI-1322terminalblock,refertoDevice-SpecificStrainGageInformationformoreinformationaboutdevice-specificsettings.

RelatedTopicsOverviewofStrainGagesSignalConditioningRequirementsforStrainGagesTroubleshootingYourStrainGageCalibrationHighAccuracyConsiderations

Device-SpecificStrainGageCalibrationInformationThefollowingdeviceshaveadditionalissuesrelatedtostraingagecalibration.SCXI-1520(withSCXI-1314terminalblock),PXI-4220OffsetNulling—Thesedevicesusehardwarenullingcircuitry.TheresultingcalibrationvaluesarestoredintheAI.Bridge.Balance.CoarsePotandAI.Bridge.Balance.FinePotattributesofyourstrainvirtualchannel.AnyresidualoffsetvalueisstoredintheAI.Bridge.InitialVoltageattributeofyourstrainvirtualchannelforadditionalsoftwarecompensation.SCXI-1121(withSCXI-1321terminalblock)OffsetNulling—UsetheoffsetnullingpotentiometercircuitontheSCXI-1321toreduceinitialoffsetbeforeperformingthecalibration.ClickMeasureasyouadjustthepotentiometertoreadthenewoffsetvalue.AnyresidualoffsetvalueisstoredintheAI.Bridge.InitialVoltageattributeofyourstrainvirtualchannelforadditionalsoftwarenullingcompensation.SCXI-1122(withSCXI-1322terminalblock)OffsetNulling—Thehardwarecannotperformoffsetnulling,sotheoffsetvalueisstoredintheAI.Bridge.InitialVoltageattributeofyourstrainvirtualchannelforsoftwarenullingcompensation.

TroubleshootingYourStrainGageCalibrationRefertothefollowinglistifyoureceiveanerrorwhilecalibratingyourstraingage:

Makesureyouhaveanactualstraingageconnectedtoyourphysicalchannel,whichisatrest(nostrain).Checkyourstrainattributesandmakesuretheyreflectthecapabilityofyourmeasurementhardwareandyourstraingagesetup.Makesureyouhavecorrectlyconnectedyourstraingage.Half-bridgeandquarter-bridgesetupsrequirecompletionnetworks.Ifyourmeasurementhardwarehasabuilt-incompletionnetwork,makesureyouprogramitinsoftwareorsetthecompletionjumpersinhardware.Additionally,quarter-bridgestraingagesetuprequiresyoutoconnectanexternalquarter-bridgecompletionresistor.Alwaysuseaprecisioncompletion-resistorwhosevalueisequaltothenominalgageresistanceofyourquarter-bridgestraingage.Refertoyourdevicedocumentationfordetails.Makesureyouhavespecifiedthecorrectlocationofyourshuntresistor.Onsomedevices,theshuntresistorlocationisfixed.Onotherdevices,youcanchoosetheshuntresistorlocation.Refertoyourdevicedocumentationtoseewheretheshuntresistorislocatedbydefault.Ifyouaredrawingalotofcurrentthroughoneormorestraingages,connecttheremotesenseinputstoyourhardware(ifsupported).Ifyouhavelongleadwireswithlargeleadresistance,connecttheremotesensetocompensateforthevoltagedropacrosstheleads.Makesureyourstraingageisproperlybondedtothestrainspecimen.Makesureyourstraingagedoesnothaveanyshortoropencircuits.

HighAccuracyConsiderationsYourstraingagemeasurementscanbeinaccurateduetooneormorefactors.Thefollowingtableliststheseerrorsandwaystominimizeeachtypeoferror.

ErrorType HowtoMinimizetheErrorGain Performfrequentshuntcalibration.

Usearemotesensortoaccountforexcitationvoltagedropacrossleadwires.Useastraingagewithahigherprecisiongagefactor.Accuratelyspecifyshuntresistancebymanuallymeasuringit.

Offset Performfrequentoffsetnulling.Useprecisioncompletionresistors(forquarter-bridgeandhalf-bridgesetup).Checkthegageresistanceofyourstraingage.Usearemotesensortoaccountforvoltagedropacrossleadwires.Checktheaccuracylimitationoftheoffsetnullingcircuit.

Noise Over-sampleyourdata.Useahardwarelowpassfilter.Useasoftwarelowpassfilter.

TemperatureDrift Performfrequentcalibration.Useatemperature-compensatedbridgetype(allexceptquarter-bridgeI).

MeasuringTemperaturewithaCurrentExcitationThermistorAthermistorisasemiconductormadefrommetaloxides,pressedintoasmallbead,disk,orothershapeathightemperatures,andcoatedwithepoxyorglass.AswithanRTD,bypassingacurrentthroughathermistor,youcanreadthevoltageacrossthethermistorandthusdetermineitstemperature.UnlikeRTDs,thermistorshaveahigherresistance(anywherefrom2,000to10,000Ω)andamuchhighersensitivity(~200Ω/°C).However,thermistorsaregenerallyusedtomeasuretemperatureonlyuptothe300°Ctemperaturerange.Becausethermistorshavehighresistance,lead-wireresistancedoesnotaffecttheaccuracyofthemeasurements.UnlikeRTDs,2-wiremeasurementsareadequate.NI-DAQmxscalestheresistanceofathermistortoatemperatureusingtheSteinhart-Hartthermistorequation:

whereTisthetemperatureinKelvins,Risthemeasuredresistance,andA,B,andCareconstantsprovidedbythethermistormanufacturer.

MeasuringTemperaturewithaThermocoupleAthermocoupleiscreatedwhentwodissimilarmetalstouch,andthecontactpointproducesasmallopen-circuitvoltagethatcorrespondstotemperature.Thermocouplemeasurementsrequiresensingofthecold-junctiontemperaturewherethethermocouplewireisconnectedtothemeasurementsystem.Therefore,signalconnectionaccessoriesshouldincludeanaccuratecold-junctionsensor,andshouldbedesignedtominimizeanytemperaturegradientsbetweenthecold-junctionsensorandthermocouplewireconnections.Othersignalconditioningrequirementsincludeamplificationandfiltering,becausethermocouplesgeneratelow-voltagesignalsandaresusceptibletonoise.Yoursystemmustalsoperformlinearizationthroughhardwareorsoftwarebecausetheoutputvoltageisnotlinearwithtemperature.

MeasuringTemperaturewithaVoltageExcitationThermistorAthermistorisasemiconductormadefrommetaloxides,pressedintoasmallbead,disk,orothershapeathightemperatures,andcoatedwithepoxyorglass.AswithanRTD,bypassingavoltagethroughathermistor,youcanreadthevoltageacrossthethermistorandthusdetermineitstemperature.UnlikeRTDs,thermistorshaveahigherresistance(anywherefrom2,000to10,000Ω)andamuchhighersensitivity(~200Ω/°C).However,thermistorsaregenerallyusedtomeasuretemperatureonlyuptothe300°Ctemperaturerange.Becausethermistorshavehighresistance,lead-wireresistancedoesnotaffecttheaccuracyofthemeasurements.UnlikeRTDs,2-wiremeasurementsareadequate.NI-DAQmxscalestheresistanceofathermistortoatemperatureusingtheSteinhart-Hartthermistorequation:

whereTisthetemperatureinKelvins,Risthemeasuredresistance,andA,B,andCareconstantsprovidedbythethermistormanufacturer.

MeasuringTemperaturewithanRTDAnRTDisatemperaturesensingdevicewithresistancethatincreaseswithtemperature.SignalconditioningisgenerallyrequiredtomeasuretemperatureusinganRTD.BecauseanRTDisapassiveresistivedevice,youmustpassacurrentthroughthedevicetoproduceameasurablevoltage.Providingcurrenttotakearesistivemeasurementisaformofsignalconditioningcalledcurrentexcitation.InadditiontoproducingcurrentexcitationfortheRTD,signalconditioningamplifiestheoutputvoltagesignal,andfiltersthesignaltoremoveunwantednoise.YoualsocanusesignalconditioningtoelectricallyisolatetheRTDandthemonitoredsystemfromtheDAQsystemandthehostcomputer.

MeasuringVoltageMostmeasurementdevicesaredesignedformeasuring,orreading,voltage.TwocommonvoltagemeasurementsareDCandAC.DCvoltagesareusefulformeasuringphenomenathatchangeslowlywithtime,suchastemperature,pressure,orstrain.ACvoltages,ontheotherhand,arewaveformsthatconstantlyincrease,decrease,andreversepolarity.MostpowerlinesdeliverACvoltage.

DigitalYoucanusethedigitalportsandlinesinyourDAQdevicestoacquireorgeneratedigitalsamples.Refertothefollowingsectionsformoreinformation:AcquiringaDigitalSample(Line)AcquiringaDigitalSample(Port)GeneratingaDigitalSample(Line)GeneratingaDigitalSample(Port)

AcquiringaDigitalSample(Line)YoucanusethedigitallinesinyourDAQdevicetoacquireadigitalvalue.Thisacquisitionisbasedonsoftwaretiming.Eachlinecorrespondstoavirtualchannelinyourtask.RefertotheNI-DAQmxHelpforinformationaboutsampletimingtypesandchangedetection.AllEandMSeriesdevicessupportTTL(transistor-transistorlogic)-compatibledigitalsignals.ATTLsignalhasthefollowingtwostates:

LogicLow=0Vto+0.8VLogicHigh=+2Vto+5V

Commonapplicationsforimmediatedigitalmeasurementsincludecontrollingrelaysandsensingexternaldevicestates,suchasthestateofaswitch.

AcquiringaDigitalSample(Port)Youcanusethedigitalport(s)inyourDAQdevicetoacquireadigitalvalue.Thisacquisitionisbasedonsoftwaretiming.Youcanconfiguretheportsindividuallytoeithermeasureorgeneratedigitalsamples.Eachportcorrespondstoavirtualchannelinyourtask.RefertotheNI-DAQmxHelpforinformationaboutsampletimingtypesandchangedetection.AllEandMSeriesdevicessupportTTL(transistor-transistorlogic)-compatibledigitalsignals.ATTLsignalhasthefollowingtwostates:


Commonapplicationsforimmediatedigitalmeasurementsincludecontrollingrelaysandsensingexternaldevicestates,suchasthestateofaswitch.

GeneratingaDigitalSample(Line)YoucanusethedigitallinesinyourDAQdevicetogenerateadigitalsample.Thisoperationisbasedonsoftwaretiming.Eachlinecorrespondstoavirtualchannelinyourtask.AllEandMSeriesdevicessupportTTL(transistor-transistorlogic)-compatibledigitalsignals.ATTLsignalhastwostates,logiclowandlogichigh:LogicLow=0Vto+0.8VLogicHigh=+2Vto+5V

Commondigitalgenerationapplicationsincludecontrollingrelaysanddrivingexternaldevices,suchasanLED.

GeneratingaDigitalSample(Port)Youcanusethedigitalport(s)inyourDAQdevicetogenerateadigitalsample.Thisoperationisbasedonsoftwaretiming.Onsomedevices,youcanconfiguretheportsindividuallytoeithermeasureorgeneratedigitalsamples.Eachportcorrespondstoavirtualchannelinyourtask.AllEandMSeriesdevicessupportTTL(transistor-transistorlogic)-compatibledigitalsignals.ATTLsignalhasthefollowingtwostates:


Commondigitalgenerationapplicationsincludecontrollingrelaysanddrivingexternaldevices,suchasanLED.

CountingEdgesInedgecounting,yourdevicecountsrisingorfallingedgesusingacounter.Youcanchoosetodoeithersingle-point(on-demandorhardwaretimed)edgecountingorbuffered(sampleclock)edgecounting.Whendoingon-demandedgecounting,eachsubsequentreadreturnsthenumberofedgescountedsincethecounterwasstarted.Ifyouperformmultiplereadswithoutfirststartingthecounter,thecounterimplicitlystartsandstopswitheachReadfunction/VIcall,andthenumberofcountededgesisnotcumulativebetweenreadcalls.Whendoinghardware-timededgecounting,thereadreturnsavalueoneachactiveedgeofthesampleclock.Inthismode,youcannotspecifyabuffer.Youmustsupplyanexternalsampleclockforhardware-timededgecounting.Whendoingbufferededgecounting,thenumberofedgescountedislatchedoneachactiveedgeofthesampleclockandstoredinthebuffer.Youmustsupplyanexternalsampleclockforbufferededgecounting.Thefollowingfigureshowsanexampleofedgecountinginwhichthecounterinadevicecountsfiveedgesontheinputterminal.

Whendoingbufferededgecounting,thenumberofedgescountedislatchedoneachactiveedgeofthesampleclockandstoredinthebuffer.Thereisnobuilt-inclockforbufferededgecounting,soyoumustsupplyanexternalsampleclock.

GeneratingaPulseUsingacountertooutputpulsesiscalledpulsegeneration.SomemeasurementdevicescangenerateTTLpulsesfromthecounter/timerofthedevice.Thepulseiseitherlow(startshigh,pulseslow,andreturnshigh)orhigh(startslow,pulseshigh,andreturnslow).Apulsecanbeusedasaclocksignal,agate,oratriggerforothermeasurementsandgenerations.Eachpulseorpulsetrainconsistsofthreeparts:

InitialDelay—TheamountoftimetheoutputremainsattheidlestatebeforegeneratingthepulseHighTime—Theamountoftimethepulseisatahighlevel(5V)LowTime—Theamountoftimethepulseisatalowlevel(0V)

UsingtheDAQAssistant,youcanconfigurehowlongapulsegeneratedwithinataskremainsathighlevelorlowlevel.ThepolarityofthepulsegenerationiscontrolledbyIdleState.WithIdleStatesettoLow,thepulsegenerationstartslowfortheInitialDelay,transitionshighforthehightime,andthentransitionslowforthelowtime.Thehighandlowtimesarethenrepeatedforthedesirednumberofpulses.WithIdleStatesettoHigh,thepulsegenerationstartshighfortheInitialDelay,transitionslowforthelowtime,andthentransitionshighforthehightime.Thelowandhightimesarethenrepeatedforthedesirednumberofpulses.Inbothcases,theoutputrestsatIdleStateafterthegenerationcompletes.Clickhereformoreinformationaboutgeneratingpulses.

MeasuringDigitalFrequencyYoucanusethecountersofyourdevicetomeasurefrequency.Tomeasurethefrequencyofasignalusingthecountersofyourdevice,usethetimebaserateofyourcounterasareferencefrequency.Toconfigureyourmeasurement,specifytheexpectedrangeoftheinputsignal,sothatNI-DAQmxcanchooseitstimebasetoprovidethehighestresolutionforthemeasurement.Youcancalculatethefrequencyofyoursignalbasedonthetimebaserateandthenumberofcountsusingthefollowingformula:Frequency(inHz)=CounterTimebaseRate/Count

Togettheperiodofthesignal,takeinverseofthefrequency.If,forexample,thetimebaserateofyourmeasurementdeviceis100MHzandyouarecounting500counts,thefrequencyoftheinputsignalis200kHz.TheCounterTimebaseRateisaknownfrequency(20MHzor100kHz)andallowsyoutomakefrequencyandtimemeasurements.Toconfigureameasurement,youspecifytheexpectedrangeoftheinputsignal.Basedonthisrange,NI-DAQmxautomaticallypickstheinternaltimebasethatprovidesthehighestresolutionforyourmeasurementandusesitasthecountertimebase.Dependingonthephaseoftheinputsignalinrelationtothestartofthemeasurement,thefirstsampleofcontinuousmeasurementsisofteninvalid.Forinstance,ifyouareperformingacontinuousperiodmeasurement,andyoustartthemeasurementwhentheinputsignalishalfwaythroughitscurrentcycle,themeasuredperiodforthefirstsampleishalfofitsexpectedvalue.Subsequentsamplesindicatethecorrectvaluesbecausetheyareguaranteedtohaveseenafullperiodoftheinputsignal.Forthisreason,thefirstsampleofcontinuousperiod,pulse-width,andsemiperiodmeasurementsoftenindicatesasmallervaluethantheactualvalue.Forcontinuousfrequencymeasurements,thefirstsampleoftenindicatesahigherfrequencythantheactualfrequency.Forfrequencymeasurements,youalsocanperformmeasurementswithoneortwocounters.Formostapplications,settingMeasurementMethodto1Counter(LowFrequency)issufficientanddesirablebecauseitusesfewerresources.However,ifyouhaveahigh-frequencyorwidelyvaryingsignal,youmaywishtouseoneofthetwocounter

measurementmethods—2Counters(HighFrequency)or2Counters(LargeRange).Dependingontherateofyourinputsignalandmeasurementmethodused,yourmeasurementissubjecttodifferentquantizationerror.NI-DAQmxautomaticallyinternallyroutesasneededtoperformthemeasurementacrosspairedcounters.

MeasuringPeriodYoucanusethecountersonyourmeasurementdevicetomeasureperiod.Periodmeasurementsmeasurethetimebetweenconsecutiverisingorfallingedges.

Theformulaforperiodisasfollows:Period(inseconds)=Count/CounterTimebaseRate

whereCountisthenumberofticksofthecountertimebasethatelapsedduringoneperiodoftheinputsignalbeingmeasured.TheCounterTimebaseRateisaknownfrequency(20MHzor100kHz)andallowsyoutomakefrequencyandtimemeasurements.Toconfigureameasurement,specifytheexpectedrangeoftheinputsignal.Basedonthisrange,NI-DAQmxautomaticallychoosestheinternaltimebasethatprovidesthehighestresolutionforyourmeasurementandusesitasthecountertimebase.Dependingonthephaseoftheinputsignalinrelationtothestartofthemeasurement,thefirstsampleofcontinuousmeasurementsisofteninvalid.Forinstance,ifyouareperformingacontinuousperiodmeasurement,andyoustartthemeasurementwhentheinputsignalishalfwaythroughitscurrentcycle,themeasuredperiodforthefirstsampleishalfofitsexpectedvalue.Subsequentsamplesindicatethecorrectvaluessincetheyareguaranteedtohaveseenafullperiodoftheinputsignal.Forthisreason,thefirstsampleofcontinuousperiod,pulse-width,andsemiperiodmeasurementsoftenindicatesasmallervaluethantheactualvalue.Forcontinuousfrequencymeasurements,thefirstsampleoftenindicatesahigherfrequencythantheactualfrequency.Forperiodmeasurements,youalsocanperformmeasurementswithoneortwocounters.Formostapplications,settingMeasurementMethodto1Counter(LowFrequency)issufficientanddesirablebecauseitusesfewerresources.However,ifyouhaveahigh-frequencyorwidelyvaryingsignal,youmaywishtouseoneofthetwocountermeasurementmethods—2Counters(HighFrequency)or2Counters(LargeRange).

Dependingontherateofyourinputsignalandmeasurementmethodused,yourmeasurementissubjecttodifferentquantizationerror.NI-DAQmxautomaticallyinternallyroutesasneededtoperformthemeasurementacrosspairedcounters.

MeasuringPositionwithaLinearEncoderOndevicesthatusetheNI-TIOtimingchip,youcanusethecounterstoperformpositionmeasurementswithencoders.Anencoderisadevicethatconvertslinearorrotarydisplacementintodigitalorpulsesignals.Linearpositioncanbemeasuredwithtwo-pulseencoders.Youcanchoosetodoeithersingle-point(on-demand)positionmeasurementorbuffered(sampleclock)positionmeasurement.ThecountermeasuresthepositionoftheencoderusingtheAandBsignals,whichareoffsetby90°.TheNI-TIOcountersalsosupporttheZindex,whichprovidesaprecisereferencepointandisavailableonsomequadratureencoders.Toconfigureameasurement,youspecifytheinitialsensorpositionthroughtheInitialPositionattribute/property,dependingonyourencodertype.YoucanalsospecifyiftheZInputTerminalisusedwiththeZIndexEnableattribute/property.ThereloadpositionuponaZindexsignal,aswellaswhenaZindexpositionshouldcauseareloadtooccurinrelationtotheAandBsignalsarealsoconfigurablethroughtheZIndexPhaseandZIndexValueattributes/properties,respectively.Whenperforminganon-demandpositionmeasurement,youfirstcalltheStartVI/functiontoarmthecounter.Eachsubsequentreadreturnsthecurrentpositionoftheencoder.Ifyouperformmultiplereadswithoutfirststartingthecounter,thecounterimplicitlystartsandstopswitheachReadfunction/VIcall,andthepositionisnotrecordedproperlybetweenreadcalls.Whendoingbufferedpositionmeasurement,thecurrentpositionislatchedoneachactiveedgeofthesampleclockandstoredinthebuffer.Thereisnoonboardclockforbufferedpositionmeasurement,soyoumustsupplyanexternalsampleclock.

MeasuringPositionwithanAngularEncoderOndevicesthatusetheNI-TIOtimingchip,youcanusethecounterstoperformpositionmeasurementswithencoders.Anencoderisadevicethatconvertslinearorrotarydisplacementintodigitalorpulsesignals.AngularpositioncanbemeasuredwithX1,X2,andX4quadratureencoders.Youcanchoosetodoeithersingle-point(on-demand)positionmeasurementorbuffered(sampleclock)positionmeasurement.ThecountermeasuresthepositionoftheencoderusingtheAandBsignals,whichareoffsetby90°.TheNI-TIOcountersalsosupporttheZindex,whichprovidesaprecisereferencepointandisavailableonsomequadratureencoders.Toconfigureameasurement,youspecifytheinitialsensorpositionthroughtheInitialAngleattribute/property,dependingonyourencodertype.YoualsocanspecifyiftheZInputTerminalisusedwiththeZIndexEnableattribute/property.ThereloadpositionuponaZindexsignal,aswellaswhenaZindexpositionshouldcauseareloadtooccurinrelationtotheAandBsignalsarealsoconfigurablethroughtheZIndexPhaseandZIndexValueattributes/properties,respectively.Whenperforminganon-demandpositionmeasurement,youfirstcalltheStartVI/functiontoarmthecounter.Eachsubsequentreadreturnsthecurrentpositionoftheencoder.Ifyouperformmultiplereadswithoutfirststartingthecounter,thecounterimplicitlystartsandstopswitheachReadfunction/VIcall,andthepositionisnotrecordedproperlybetweenreadcalls.Whendoingbufferedpositionmeasurement,thecurrentpositionislatchedoneachactiveedgeofthesampleclockandstoredinthebuffer.Thereisnoonboardclockforbufferedpositionmeasurement,soyoumustsupplyanexternalsampleclock.

MeasuringPulseWidthYoucanusethecountersonyourmeasurementdevicetomeasurepulsewidth.Pulse-widthmeasurementsmeasurethetimebetweeneitherarisingandafallingedge,orafallingandarisingedge.

Theformulaforpulsewidthisasfollows:Pulsewidth(inseconds)=Count/CounterTimebaseRate

whereCountisthenumberofticksofthecountertimebasethatelapsedduringonepulsewidthoftheinputsignalbeingmeasured.TheCounterTimebaseRateisaknownfrequency(20MHzor100kHz)andallowsyoutomakefrequencyandtimemeasurements.Toconfigureameasurement,youspecifytheexpectedrangeoftheinputsignal.Basedonthisrange,NI-DAQmxautomaticallypickstheinternaltimebasethatprovidesthehighestresolutionforyourmeasurementandusesitasthecountertimebase.Dependingonthephaseoftheinputsignalinrelationtothestartofthemeasurement,thefirstsampleofcontinuousmeasurementsisofteninvalid.Forinstance,ifyouareperformingacontinuousperiodmeasurement,andyoustartthemeasurementwhentheinputsignalishalfwaythroughitscurrentcycle,themeasuredperiodforthefirstsampleishalfofitsexpectedvalue.Subsequentsamplesindicatethecorrectvaluessincetheyareguaranteedtohaveseenafullperiodoftheinputsignal.Forthisreason,thefirstsampleofcontinuousperiod,pulse-width,andsemiperiodmeasurementsoftenindicatesasmallervaluethantheactualvalue.Forcontinuousfrequencymeasurements,thefirstsampleoftenindicatesahigherfrequencythantheactualfrequency.

MeasuringSemiperiodYoucanusethecountersonyourmeasurementdevicetomeasuresemiperiod.Semiperiodmeasurementsmeasurethetimebetweenconsecutiveedges,alternatingbetweenhightimeandlowtime.

Theformulaforsemiperiodisasfollows:Semiperiod(inseconds)=Count/CounterTimebaseRate(inHz)

whereCountisthenumberofticksofthecountertimebasethatelapsedduringthehighorlowtimeofthesignaltomeasure.TheCounterTimebaseisaclockwithaknownfrequency(20MHzor100kHz)andallowsyoutomakefrequencyandtimemeasurements.Toconfigureameasurement,specifytheexpectedrangeoftheinputsignal.Basedonthisrange,NI-DAQmxautomaticallychoosestheinternaltimebasethatprovidesthehighestresolutionforyourmeasurementandusesitasthecountertimebase.Dependingonthephaseoftheinputsignalinrelationtothestartofthemeasurement,thefirstsampleofcontinuousmeasurementsisofteninvalid.Forinstance,ifyouareperformingacontinuousperiodmeasurement,andyoustartthemeasurementwhentheinputsignalishalfwaythroughitscurrentcycle,themeasuredperiodforthefirstsampleishalfofitsexpectedvalue.Subsequentsamplesindicatethecorrectvaluessincetheyareguaranteedtohaveseenafullperiodoftheinputsignal.Forthisreason,thefirstsampleofcontinuousperiod,pulse-width,andsemiperiodmeasurementsoftenindicatesasmallervaluethantheactualvalue.Forcontinuousfrequencymeasurements,thefirstsampleoftenindicatesahigherfrequencythantheactualfrequency.

MeasuringTwo-EdgeSeparationYoucanusethecountersonyourmeasurementdevicetomeasuretwo-edgeseparation.Two-edgeseparationisthetimebetweentherisingorfallingedgeofonedigitalsignal(SignalAinthefollowingfigure)andtherisingorfallingedgeofanotherdigitalsignal(SignalBinfigure).

Theformulafortwo-edgeseparationisasfollows:Two-EdgeSeparation(inseconds)=Count/CounterTimebaseRate(inhertz)

whereCountisthenumberofcountertimebaseticksbetweenthespecifiededgeofthefirstsignalandthespecifiededgeofthesecondsignal.TheCounterTimebaseRateisaknownfrequencyformakingfrequencyandtimemeasurements.Toconfigureameasurement,specifytheexpectedrangeoftheinputsignal.Basedonthisrange,NI-DAQmxautomaticallyselectstheinternaltimebasethatprovidesthehighestresolutionforyourmeasurementandusesthattimebaseasthecountertimebase.

MeasurementsUsingTwoCountersYoucanmeasuredigitalfrequencyortheperiodofaTTLsignalusingtwocounters.Twomethodsarethehigh-frequencymeasurementmethodandthelargerangemeasurementmethod.

High-FrequencyMeasurementMethodIfyoumeasurethedigitalfrequencyortheperiodofaTTLsignalwithhigherfrequency,youcanusethehigh-frequencymethod.Toperformmeasurementsusingthismethod,NI-DAQmxusesthepairedcountertogenerateapulsetrainwithaperiodspecifiedusingthemeasurementtimeattribute/property.Themeasurementtimeisgenerallymuchlargerthantheperiodoftheinputsignalbeingmeasuredtoreducequantizationerror.However,themeasurementtimemustbesmallenoughtokeepthecounterfromrollingover.Themeasurementcountercountsthenumberofperiodsoftheinputsignalthatoccurduringthemeasurementtime,averagestheresults,andreturnstheaveragedvalueintheReadfunction/VI.Thevaluereturnediscalculatedasfollows:Period(inseconds)=MeasurementTime/NumberofPeriodsCountedFrequency(inHertz)=NumberofPeriodsCounted/MeasurementTime

TipAsyouincreasetime,theaccuracyofthereadingalsoincreases.However,ifyouspecifytoolargeatime,thecountermayrollover,leadingtoaninaccuratefrequencyorperiodmeasurement.

LargeRangeMeasurementMethodIfyoumeasurethedigitalfrequencyortheperiodofaTTLsignal,youcanusethistwo-countermethodtomeasuresignalswithlargeranges.Thismethodisusefulwhenyouhaveawidelyvaryingsignaltomeasureandwouldlikeincreasedaccuracythroughouttheentirerange.Refertothequantizationerrorsectionformoreinformationonincreasingmeasurementaccuracywiththelarge-rangemeasurementmethod.Youcanalsousethismethodtomeasuresignalfrequenciesthatarefasterthanyourcountertimebaserateaslongastheinputsignaldoesnotexceedthemaximuminputfrequencysupportedbythecounter.Toperformmeasurementsusingthismethod,NI-DAQmxusesthepairedcountertodividetheinputsignalbyavaluespecifiedbyDivisor.However,youneedtobecarefultheDivisoryouchoosedoesnotcausethecountertorollover.ThisDivisorhastheeffectofshiftingthemeasurablefrequencyrangeupward.Forexample,ifyouareusinga24-bitcounterandyourCounterTimebaseRateis100kHz,themeasurablefrequencyrangeisapproximately0.006Hzto50kHz.However,withaDivisorof4,themeasurablefrequencyrangebecomes0.024Hzto200kHz.Thedividedinputsignalisthenmeasuredusingthelowfrequencyonecountermeasurementmethod.ThemeasuredperiodisthenscaledusingtheDivisor,andreturnedaccordingtothefollowingformula:Period=MeasuredPeriod/DivisorFrequency=Divisor/MeasuredPeriod

TipAsyouincreasethedivisor,theaccuracyofthereadingalsoincreases.However,ifyouspecifytoolargeadivisor,thecountermayrollover,leadingtoaninaccuratefrequencyorperiodmeasurement.

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—aVIorfunctionthatbeginsanoperationandreturnspriortothecompletionorterminationoftheoperation.

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.Itmaybemadeupofoneormoresignalwires(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/O

points.Adeviceoftenisconnectedtoahostcomputerthroughsometypeofcommunicationnetwork.

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.

mxcncpts.chm::/Events.html

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.

multiplexed AnSCXIoperatingmodeinwhichanaloginputchannels

mode aremultiplexedintoonemoduleoutputsothatthecabledDAQdevicehasaccesstothemultiplexedoutputaswellastheoutputsonallothermultiplexedmodulesinthechassisthroughtheSCXIbus.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,thisnonlinearityspecificationmustbeaddedtotherelativeaccuracy

specificationoftheDAQproductwiththeADC.

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'sRatio

Thenegativeratioofthestraininthetransversedirection(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.

pulsed Aformofcountersignalgenerationbywhichapulseis

output generatedwhenacounterreachesacertainvalue.PWM pulse-widthmodulationPXI PCIeXtensionsforInstrumentation—arugged,open

systemformodularinstrumentationbasedonCompactPCI,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-levelsignalsaresenttomeasurementdevicesinthenoisyPC

environment.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—aVIorfunctionthatbeginsanoperationandreturnsonlywhentheoperationiscomplete.

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-based

sensors.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.

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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 351210311210

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