虚拟相位差测量仪的设计

Lesson5

ClustersTOPICSIntroductiontoClustersClusterFunctionsErrorClusters1ClustersDatastructurethatgroupsdatatogetherDatamaybeofdifferenttypesAnalogoustostructinCorarecordinPascalElementsmustbeeitherallcontrolsorallindicatorsThoughtofaswiresbundledintoacable21. SelectaClustershellfromtheArray&ClustersubpaletteClusterControlsandIndicators2. Placeobjectsinsidetheshell3CreatingClusterConstants1. SelectClusterConstantshellfromtheClustersubpalette2. PlaceobjectsintheClustershell4ClusterOrderElementshavealogicalorder(startwith0)Tochangeorder,right-clicktheborderandselectReorderControlsinCluster...

5UsingClusterstoPassDatatoSubVIsUseclusterstopassseveralvaluestooneterminalOvercomes28-terminallimitSimplifieswiring

6ClusterFunctions-BundleBundleBundle

ByNameCreatenewclusterModifyexistingclusterMusthaveanexistingclustertousethisfunction.7ClusterFunctions-UnbundleUnbundleUnbundleByName8ErrorClusterUsetheerrorinanderroroutclustersineachVIyouuseorbuildtohandleerrorsintheVI.TheerrorclusterslocatedontheControls»Array&Clusterpaletteincludethecomponentsofinformationshown9ErrorClusterDetailsStatusisaBooleanvaluethatreportsTRUEifanerroroccurred.MostVIs,functions,andstructuresthatacceptBooleandataalsorecognizethisparameter.Codeisasigned32-bitintegerthatidentifiestheerrornumerically.Anon-zeroerrorcodecoupledwithastatusofFALSEsignalsawarningratherthanafatalerror.Sourceisastringthatidentifieswheretheerroroccurred.10ErrorHandlingwithClustersLabVIEWdoesnothandleerrorsautomatically.InLabVIEW,youcanmaketheseerrorhandlingdecisionsontheblockdiagramoftheVI.ErrorhandlinginLabVIEWfollowsthedataflowmodel.JustasdataflowthroughaVI,socanerrorinformation.WiretheerrorinformationfromthebeginningoftheVItotheend.ErrorCluster11SimpleErrorHandlerUsetheSimpleErrorHandlertohandletheerrorattheendoftheexecutionflow.TheSimpleErrorHandlerislocatedontheFunctions»AllFunctions»TimeandDialogpalette.WiretheerrorclustertotheErrorIn(noerror)input.12UsingWhileLoopsforErrorHandlingYoucanwireanerrorclustertotheconditionalterminalofaWhileLooptostoptheiterationoftheWhileLoop.OnlytheTRUEorFALSEvalueofthestatusparameteroftheerrorclusterispassedtotheterminal.Whenanerroroccurs,the

WhileLoopstops.13Clustersgroupdataelementsofmixedtypes.Aclustercannotcontainamixtureofcontrolsandindicators.Tocreateaclustercontrolorindicator,selectaclusterontheControls»»Array&Clusterpalette,placeitonthefrontpanel,anddragcontrolsorindicatorsintotheclustershell.UsetheClusterfunctionslocatedontheFunctions»AllFunctions»Clusterpalettetocreateandmanipulateclusters.Errorcheckingtellsyouwhyandwhereerrorsoccur.Theerrorclusterreportsthestatus,codeandsourceoftheerror.UsetheerrorclustercontrolsandindicatorstocreateerrorinputsandoutputsinsubVIs.Summary14Lesson6

PlottingDataTOPICSWaveformChartsWaveformandXYGraphsIntensityGraphs15WaveformChartsSelectedfromtheControls»GraphsandChartspalette16WiringtoChartsSingle-PlotChartMultiple-PlotChart17ModifyingChartPropertiesChangetheappearanceSettheformatandprecisionoftheaxisChoosetheplottypeEditthescalesDocumentthechart18CustomizingChartsandGraphsRight-clickandselectVisibleItemstoviewthefollowingitems:PlotLegendDigitalDisplayScrollbarXandYScaleGraphPaletteScaleLegendGraphPaletteScaleLegendZoomSubpalette19•SelectedfromtheGraphsubpalette•WaveformGraph–Plotanarrayofnumbersagainsttheirindices•XYGraph––PlotonearrayagainstanotherPlotLegend(pointandlinestyles)GraphPaletteScaleLegendGraphs20UniformXaxisInitialX=0.0DeltaX=1.0UniformXaxisyouspecifypointspacingSingle-PlotWaveformGraphs21Multiple-PlotWaveformGraphsEachrowisaseparateplot:InitialX=0DeltaX=1Eachrowisaseparateplot:BundlespecifiespointspacingoftheXaxis22Non-uniformXaxisSeparateXandYarraysdefinedatapointsXYGraphs23ChartandGraphUseSummaryUsetheContextHelpwindowwithchartsandgraphs24IntensityPlotsandGraphsUsefulindisplayingterrain,temperaturepatterns,spectrumanalysis,andimageprocessingDatatypeisa2Darrayofnumbers;eachnumberrepresentsacolorUsetheseoptionstosetanddisplaycolormappingschemeCursoralsoaddsathirddimension25Thewaveformchartisaspecialnumericindicatorthatdisplaysoneormoreplots.Thewaveformcharthasthefollowingthreeupdatemodes:Astripchartshowsrunningdatacontinuouslyscrollingfromlefttorightacrossthechart.Ascopechartshowsoneitemofdata,suchasapulseorwave,scrollingpartwayacrossthechartfromlefttotheright.Asweepworkssimilarlytoascopeexceptitshowstheolddataontherightandthenewdataontheleftseparatedbyaverticalline.WaveformgraphsandXYgraphsdisplaydatafromarrays.Right-clickawaveformchartorgraphoritscomponentstosetattributesofthechartanditsplots.Summary26YoucandisplaymorethanoneplotonagraphusingtheBuildArrayfunctionandtheBundlefunctionforchartsandXYgraphs.Thegraphbecomesamultiplotgraphwhenyouwirethearrayofoutputstotheterminal.Whenyouwiredatatochartsandgraphs,usetheContextHelpwindowtodeterminehowtowirethem.Youcanuseintensitychartsandgraphstoplotthree-dimensionaldata.Thethirddimensionisrepresentedbydifferentcolorscorrespondingtoacolormappingthatyoudefine.Intensitychartsandgraphsarecommonlyusedinconjunctionwithspectrumanalysis,temperaturedisplay,andimageprocessing.Summary,cont.27Lesson7

MakingDecisionsinaVITOPICSDecisionmakingwiththeSelectfunctionCaseStructuresFormulaNodes28SimpleDecision:SelectFunctionIfTempScaleisTRUE,passtopinput;

iftempscaleisFALSE,passbottominput.IfthedecisiontobemadeismorecomplexthanaSelectfunctioncanexecute,aCaseStructuremaybewhatisrequired.29BooleanCaseStructureExample:IfTempScaleisTRUE,executeTruecase;iftempscaleisFALSE,executeFalsecase.CaseStructures30•IntheStructuressubpaletteofFunctionspalette•Enclosenodesordragtheminsidethestructure•Stackedlikeadeckofcards,onlyonecasevisibleatatimeCaseStructures31BooleanandNumericCasesWireallpossibleoutputsofthecasestructure32String,Enum,andErrorCasesStringCaseEnumCaseErrorCase33IntheStructuressubpaletteImplementcomplicatedequationsVariablescreatedatborderVariablenamesarecasesensitiveEachstatementmustterminatewithasemicolon(;)ContextHelpWindowshowsavailablefunctionsNotesemicolonFormulaNode34DecisionMakingwithFormulaNodesTwodifferentwaysofusinganif-thenstatementinaFormulaNodeBothstructuresproducethesameresult35TheSelectfunctionisusedtochoosebetweentwoinputsdependant

onabooleaninput.ACasestructurehastwoormorecases.Onlyonecaseisvisibleatatime,andthestructureexecutesonlyonecaseatatime.IfthecaseselectorterminalisBoolean,thestructurehasaTRUE

caseandaFALSEcase.Iftheselectorterminalisaninteger,string,orenumeratedtypevalue,thestructurecanhaveupto231–1cases.Inputsareavailabletoallcases,butcasesdonotneedtouseeachinput.Ifatleastoneoutputtunnelisnotdefined,alloutputtunnelson

thestructureappearaswhitesquares.FormulaNodesareusefulforcomplicatedequationsandforusing

existingtext-basedcode.Asemicolon(;)mustterminateeachstatement.Summary36Lesson8

StringsandFileI/OTOPICSHowtocreatestringcontrolsandindicatorsHowtouseseveralStringfunctionsAboutfileI/OoperationsHowtousethehigh-levelFileI/OVIsHowtousethelow-levelFileI/OVIsHowtoformattextfilesforuseinspreadsheets37Astringisasequenceofdisplayableor-characters(ASCII)Manyuses—displayingmessages,instrumentcontrol,fileI/OStringcontrol/indicatorisintheControls»StringsubpaletteStrings38StringDisplayModesNormaldisplayPassworddisplay\codedisplayHexdisplay39ConcatenateStrings(spaceshere)StringLengthStringFunctions40StringFunctionsStringSubsetMatchPattern41ConvertingNumericstoStrings:BuildString42ConvertingStringstoNumerics:

ScanFromString43EditFormatStringScanFromStringFunction44FileInputandOutputFourHierarchyLevels:High-levelFileVIsIntermediateFileVIsandFunctionsAdvancedFileFunctionssubpaletteExpressVIs45WritetoSpreadsheetFileReadfromSpreadsheetFileWriteCharacterstoFileReadCharactersfromFileReadLinesfromFileHigh-levelFileI/OVIs46FileI/OProgrammingModel-IntermediateOpen/

Create/

ReplaceFileReadand/or

WritetoFileCloseFileCheckforErrors47WritetoFileExampleOpen/Create/ReplaceopenstheexistingfileTEST1.DATandgeneratesrefnumanderrorclusterWriteFilewritesthedataCloseFileclosesthefileSimpleErrorHandlerchecksforerrors48ReadingDatafromaFileOpen/Create/ReplaceopensthefileReadFilereadsthespecifiednumberofbytesfromthefileCloseFileclosesthefileSimpleErrorHandlerchecksforerrors49FormattingaSpreadsheetStringSpreadsheetsarepopulartoolsfordatahandlingandanalysisTherearemanyformatsforspreadsheetdata.Oneofthemostpopularistab-delimited:ColumnsareseparatedbyatabcharacterRowsareseparatedbyanend-of-linecharacterTabEndofLineAspreadsheetyields:50CreatingaSpreadsheetFileCanreplaceFormatIntoStringandWriteFilewithFormatIntoFileinaboveexample51WriteLabVIEWMeasurementFileIncludestheopen,write,closeanderrorhandlingfunctionsHandlesformattingthestringwitheitherataborcommadelimiterMergeSignalsfunctionisusedtocombinedataintothedynamicdatatype52StringsgroupsequencesofASCIIcharacters.UsethestringcontrolandindicatorlocatedontheControls»String&Pathpalettetosimulatetextentr