外文翻译基于LabVIEW的虚拟示波器研究和开发Word格式.docx

外文翻译基于LabVIEW的虚拟示波器研究和开发Word格式.docx

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BasedonLabVIEW

Abstract:

ThispaperintroducesthedesignprocessofavirtualoscillographbasedonLabVIEW.Mainlyanalyzestheamplitudevalueandtimebaseadjustingmethodsduringthereal-timedisplay.Atthesametime,itsimplyintroducesthebasicthoughtwhenmeasuringtheperiodandfrequencyofthewaveformgatevoltagemethodanditsapplication.Attheendofthispaper,combiningtheparametermeasurementandwaveformdisplayofthevirtualoscillographwiththemodernmotorclose-looplock-phasespeedcontrol,itanalyzestheparametermeasurement'

seffectinPIDcontrol.

Keywords:

VirtualOscillograph;

Time-Base;

MotionControl

Ⅰ.INTRODUCTION

Intherapidlydevelopingindustrycontrolfield,measuringtechnologiesandapparatusbecomemoreandmoreimportant.Butbecauseofthedisadvantagesofthetraditionalinstrumentssuchashighprice,singlefunction,badexpansibility,etc.,theycanhardlymeettheindustryrequirement.Withthedevelopmentofcomputertechnologiesandvirtualinstruments（VIforshort）,thescopedesignedbyusersbecomeswidely.TherearemanydifferentfunctionswiththesamehardwarewhichcanmaketwoormoremachinesworksynchronouslywiththeadvancedbustechnologiessuchasPXIbustechnology[1].Virtualinstrumentsbecomemoreandmorepopularforitsupstandingcharacteristicslikelowcost,multi-function,facilityandsoon.

Allmeasuringinstrumentsconsistofthreeparts:

dataacquisition,dataanalysisandresultsoutput[2].Inthesethreeparts,dataacquisitioncanbedonebythesystemhardwarelikeA/DmoduleordigitalI/Omodules.Dataanalysisandresultsoutputcanbecompletedbysoftwaresystembasedoncomputer.So,ifgivensomenecessarydataacquisitionhardware,ameasuringinstrumentbasedoncomputercanbeconstituted.Thesoftwaretechnologyistheessentialoneinthevirtualinstrument.[3]VisualC++,LabVIEW,LabWindows/CVI,VEEetc.arealldevelopmentsoftwareenvironment.LabVIEWisagraphicprogramminglanguagecalledGlanguage,whichcanbeusedinGPIB,VXI,PXI,PCIBusanddataacquisitioncardsbasedhardwaresystem,haspowerfulanalyzingability.Itsgraphicprogrammingmethodcanbeusedtofinishthetotalprogrambydataflowclearlyandsimply.Usingitsembeddedboardcarddriverinterface,wecanconvenientlyoperateaboardcard.[4,5]

Multi-channeldigitaloscillograph,whichmainlyusedinreal-timedataacquisition,isoneofthemostwidelyusedgeneralmeasuringinstruments.Italsocandisplaythechangesofsomeelectricsignalsandcomparethedifferencesamongdifferentsignals.Sotheresearchanddevelopmentofvirtualoscillographisthehotspotinthearea.MakinguseoftheGraphplatteinLabVIEW,youcanconvenientlyacquirethedynamicwaveformsandmakethemdisplayed.ButmostvirtualoscillographsbasedonLabVIEWusetheGraphplattetooperateandanalyzethewaveformdata.Althoughthisisveryfaciletouse,italsohasmanydisadvantages:

（1）Whenthewaveformchangesallthetime,thescreenwillkeeprefreshingandthegraphplattecouldnotproperlywork.

（2）Theoperationmethodcan'

tsatisfymostofoperatorsbecauseitisdifferentfromthetraditionoscillographinoperation.Tosolvetheseproblems,thispaperbringsforwardsomeways.Inthereal-timewaveformdisplay,weredevelopthewaveformoperationandintroducesomerelatedsoftwarearithmetic.Itintroducestheexploitingthinkingofadjustingdynamictimebaseandputforwardtwoconcepts:

theFIFOprocessandE-Mprocess.Inaddition,itintroducesasuccessfulgate-voltagemeasurewayinthemeasurementoftheperiodandfrequency,andbasedonwhich,thepaperputsforwardtheapplicationintheclose-looplock-phaseSystem.

II.RESEARCHONTHEMULTICENTERDIGITAL

OSCILLOGRAPH'

SSOFTWAREARITHMETIC

Thevirtualoscillographintroducedbythispaperismainlyusedinlaboratoryforthemeasurementandstorageofvariousanalogsignals.Themainfunctionsare:

dataacquisition,waveformdisplay,parametermeasurement,waveformstorageandreplayetc.Ithas64analogsignalinputchannelsandcantake8signalobservationsatthesametimewiththechoiceofswitchmatrix.Accordingtotherequirement,weusetheNI-6133Daqcardforthedataacquisition.TheblockdiagramofvirtualoscillographisshowninFig.1:

[6]

Nowwewillintroducethesoftarithmetictothebasicfunctionsofvirtualoscillograph.

A.CharacteristicsofGraphControl

InLabVIEW,therearethreecontrolsforwaveformdisplaying:

Graph,Chatandx-ygraph.Everycontrolhasitsownadvantages.ThispapertakesGraphcontrolforexampletodiscussthesoftarithmetictothebasicfunctionofvirtualoscillograph.Graphoscillographdisplaysallwaveformdatainputinthescreenatatime.Everytimewhenthewaveformdataareinput,thescreenwillbefreshed.[7]Usingitsownoperationtools,youcanmove,zoomthewaveformorusethecursorstomeasuretheparameters.Butitcouldnotworkwellondynamicwaveform.Soit'

snecessarytodevelopamoreconvenientoperationtooltoreal-timedisplayofdynamicwaveform.

Inthevirtualoscillographintroducedinthispaper,therearesomebasicfunctionssuchasamplitudeandpositionvalueadjustment,timebasechange,triggermodeselectionetc.Theoscillograph'

sfrontpanelisshowninfig.2.

B.AmplitudeValueAdjustment

Multi-centeroscillographcandisplaymorethanonewaveformatthesametime,soitisveryconvenienttocompareeverysignalchange.Everywaveformdisplayedshouldbeoperatedseparatelythroughtheselectingboxonthefrontpanel.Atfirst,wedistributethescreeninto10×

10gridsandseteverychannelaY-axis.Thevalueofeveryoneofthe10gridsintheY-axisisequaltothevalueofrelatedamplitudeknobcontrol.Withthepropertynodeofthewaveformgraph,youcansettheminimumvalueofeachY-axisas-5timesmuchastheknobvaluewhereasthemaximumvalueset5times.Sowhenyouchangetheamplitudeknobvalue,theminimumandthemaximumvalueoftherelevantY-axisshouldbechangedatthesametime,thewaveformdisplaycanbezoomedasrequired,andthezeropointpositioniskeptintheoriginallocation.

UseanarraytosavetheamplitudevalueseveryY-axischanged.Whenachannelisselected,putitsoldamplitudevaluetotheknobfirst;

andafteradjusting,replacetherelatedarrayelementwiththenewvalue.Andthentheamplitudevaluechangefunctionisfinished.

C.TimeBaseAdjustment

Timebaseadjustingisoneofthebasicfunctionsinoscillograph.Thetimebaseadjustingknob'

svalueshowsthetimeofeveryonegridofX-axisinthescreenwhichisthenodusduringtheoscillographdesignprocedure.

1）BasicClew

AccordingtothecharacteristicsoftheGraphcontrol,itdisplaysallthedatainputatatime.SodistributetheX-axisinto10gridsandmakeeverygrid'

stimet.IfthewaveformcouldbestridethewholeX-axis,thetimespenttocollectallthedatais10t.Supposetheboard'

ssamplingrateisf,inotherword,theboardcollectsfdataeverysecond.SothenumberNneededinthewaveformis:

N=f×

l0t=l0ft

（1）

Keepingtheboardsamplingatthefrequencyoff,theprogramreadsNdatapointsfromtheboardmemoryandputthemtotheoscillographineveryloop.ChangethetvalueistochangetheNvaluereadfromboardmemoryeverytime,andthusadjustthetimebaseinthereal-timesampling.

Butthroughtheexperimentwecansee,whenthetimebaseistoolong（>

100ms）ortooshort（<

500us）,thewaveformdisplayedhastimelagstodifferentextend.Thatisbecausewhenthetimebaseistoolong（ifthelengthoftheneededwaveformexceeds1second）,wemustwaitforenoughtimetogetallneededdatacollectedbytheboard,anddisplaythemonthescreenatatime.Sothatcancausediscontinuouswaveformdisplayedinthescreen.Whenthetimebaseistooshort,theNvaluereadeveryloopistoosmall,thenumberofdatapointsinonesecondshouldbereadformanytimes.Thereisanotherworktobedoneatthesametimeeveryloopinaddition.Soitwillcausethattheolddatacannotbereadintimeandmaybecoveredbythenewdatabecausetheboardissamplingalltime,theboardmemorywilloverflow.Soitisneededtodisposethenumberreadfromboardatlongandshorttimebaseseparately.

2）Longtimebase

Toavoidthetimelagdiscussedabove,itmustreducethenumberofdatareadfromsamplingboardeveryloop.ConsideringthedisplaycharacteristicsofGraphcontrol,itcannotputthedatapointsreadfromboardstothegrapheveryloopbecauseitwillmaketheoscillographrefreshingallthetime,andthewaveformdisplayedcouldnotbestridethewholeX-axis.Anarraycouldbesettosavethewaveformdatapointsdisplayed.Thearray'

scapacityisN,whichisthenumberofdatapointscalculatedviaEq.

（1）.Supposethenumberofdatapointsreadfromboardcardeverytimeisafixedvaluem,whichisthenumberofdatapointstobereadatthepropertimebase.

Thewholeprocedureismadeupoftwoparts.First,setthewholearrayNULL.Atthebeginningofthedisplayprocedure,thearrayisnotfull.Soputthenewmdatapointsintotheendofthearray（Enqueue）,andthendisplaythewholearrayvalueinthegraphcontrol.Acontinuouslymovingwaveformshouldbeshowedinthescreen.Second,whenthearrayisfull,getridoffirstmelementsofthearray;

movetherestN-melementsforwardthebeginningofthearray;

andputthenewmdatapointsintotheendofthearray.WecallthisprocessFIFO.Thenafullwaveformshouldbeshowedinthescreen,fromonesidetotheotherside.TheEnqueueandFIFOareshowninFig3.

Becausethenumberofdatapointsmread