文献翻译——虚拟仪器

第1页外文文献资料LabVIEWLabVIEWisahighlyproductivegraphicalprogramminglanguageforbuildingdataacquisitionaninstrumentationsystems.WithLabVIEW,youquicklycreateuserinterfacesthatgiveyouinteractivecontrolofyoursoftwaresystem.Tospecifyyoursystemfunctionality,yousimplyassembleblockdiagrams-anaturaldesignnotationforscientistsandengineers.Tistightintegrationwithmeasurementhardwarefacilitatesrapiddevelopmentofdataacquisition,analysis,andpresentationsolutions.LabVIEWcontainspowerfulbuilt-inmeasurementanalysisandagraphicalcompilerforoptimumperformance.LabVIEWisavailableforWindows2000/NT/Me/9x,MacOS,Linux,SunSolaris,andHP-UX,andcomesinthreedifferentdevelopmentsystemoptions.FasterDevelopmentLabVIEWacceleratesdevelopmentovertraditionalprogrammingby4to10times!WiththemodularityandhierarchicalstructureofLabVIEW,youcanprototype,design,andmodifysystemsinashortamountoftime.YoucanalsoreuseLabVIEWcodeeasilyandquicklyinotherapplications.BetterInvestmentUsingaLabVIEWsystem,eachuserhasaccesstoacompleteinstrumentationlaboratoryatlessthanthecostofasinglecommercialinstrument.Inaddition,userconfigurableLabVIEWsystemsareflexibleenoughtoadapttotechnologychanges,resultinginabetterbong-terminvestment.OptimalPerformanceAllLabVIEWapplicationsexecuteatcompiledspeedforoptimalperformance.WiththeLabVIEWProfessionalDevelopmentSystemorApplicationBuilder,youcanbuildstand-aloneexecutablesorDLLsforsecuredistributionofyourcode.YoucanevencreatesharedlibrariesorDLLsto第2页callLabVIEWcodefromotherprogramminglanguages.OpenDevelopmentEnvironmentWiththeopendevelopmentenvironmentofLabVIEW,youcanconnecttootherapplicationsthroughActiveX,theWeb,DLLs,sharedlibraries,SQL(fordatabases),DataSocket,TCP/IP,andnumerousotherprotocols.UseLabVIEWtoquicklycreatenetworkedmeasurementandautomationsystemsthatintegratethelatesttechnologiesinWebpublishingandremotedatasharing.LabVIEWalsohasdriverlibrariesavailableforplug-indataacquisition,signalconditioning,GPIB,VXI,PXI,computer-basedinstruments,serialprotocols,imageacquisition,andmotioncontrol.InadditiontotheLabVIEWdevelopmentsystems,NationalInstrumentsoffersavarietyofadd-onmodulesandtoolsetsthatextendthefunctionalityofLabVIEW.Thisenablesyoutoquicklybuildcustomizable,robustmeasurementandautomationsystems.LabVIEWDataloggingandSupervisoryControlModuleForhighchannelcountanddistributedapplications,theLabVIEWDateloggingandSupervisoryControlModuleprovidesacompletesolution.ThismoduledeliversI/Omanagement,eventloggingandalarmmanagement,distributedlogging,historicalandreal-timetrending,built-insecurity,configurablenetworkingfeatures,OPCdeviceconnectivity,andover3,300built-ingraphics.LabVIEWReal-TimeForapplicationsthatrequirereal-timeperformance,NationalInstrumentsoffersLabVIEWReal-Time.LabVIEWReal-TimedownloadsstandardLabVIEWcodetoadedicatedhardwaretargetrunningareal-timeoperatingsystemindependentfromWindows.LabVIEWVisionDevelopmentModuleTheLabVIEWVisionDevelopmentModuleisforscientists,automationengineers,andtechnicianswhoaredevelopingLabVIEWmachinevisionandscientificimagingapplications.TheLabVIEWVisionDevelopmentModuleincludesIMAQVision,alibraryofvisionfunctions,andIMAQVisionBuilder,aninteractiveenvironmentforvisionapplications.Unlikeanyothervisionproducts,IMAQVisionBuilderandIMAQVisionworktogethertosimplifyvisionsoftwaredevelopmentsothatyoucanapplyvisiontoyourmeasurement第3页andautomationapplications.CountlessApplicationsLabVIEWapplicationsareimplementedinmanyindustriesworldwideincludingautomotive,telecommunications,aerospace,semiconductor,electronicdesignandproduction,processcontrol,biomedical,andmanyothers,Applicationscoverallphasesofproductdevelopmentfromresearchtodesigntoproductionandtoservice.ByleveragingLabVIEWthroughoutyourorganizationyoucansavetimeandmoneybysharinginformationandsoftware.TestandMeasurementLabVIEWhasbecomeanindustry-standarddevelopmenttoolfortestandmeasurementapplications.WithTestStand,LabVIEW-basedtestprograms,andtheindustryslargestinstrumentdriverlibrary,youhaveasingle,consistentdevelopmentandexecutionenvironmentforyourentiresystem.ProcessControlandFactoryAutomationLabVIEWisusedinnumerousprocesscontrolandfactoryautomationapplications.ManyscientistsandengineerslooktoLabVIEWforthehighspeed,highchannelcountmeasurementandcontrolthatgraphicalprogrammingoffers.Forlarge,complexindustrialautomationandcontrolapplications,theLabVIEWDataloggingandSupervisoryControlModuleprovidesthesamegraphicalprogrammingasLabVIEW,butisdesignedspecificallyformonitoringlargenumbersofI/Opoints,communicatingwithindustrialcontrollersandnetworks,andprovidingPC-basedcontrol.MachineMonitoringandControlLabVIEWisidealformachinemonitoringandpredictivemaintenanceapplicationsthatneeddeterministiccontrol,vibrationanalysis,visionandimageprocessing,andmotioncontrol.WiththeLabVIEWplatformofproductsincludingLabVIEWReal-Timeforreal-timedeterministiccontrolandtheLabVIEWDataloggingandSupervisoryControlModule,scientistsandengineerscancreatepowerfulmachinemonitoringandcontrolapplicationsquicklyandaccurately.ResearchandAnalysisTheintegratedLabVIEWmeasurementanalysislibraryprovideseverythingyouneedinananalysispackage.ScientistsandresearchershaveusedLabVIEW第4页toanalyseandcomputerealresultsforbiomedical,aerospace,andenergyresearchapplications,andinnumerousotherindustries.Theavailablesignalgenerationandprocessing,digitalfiltering,windowing,curve-fitting,Forspecializedanalysis,suchasjointtime-frequencyanalysis,wavelet,andmodel-basedspectralanalysis,LabVIEWoffersthespeciallydesignedSignalProcessingToolset.TheSoundandVibrationToolsetoffersoctaveanalysis,averagedandnonaveragedfrequencyanalysis,transientanalysis,weightedfiltering,andsound-levelmeasurement,andmore.DrawYourOwnSolutionWithLabVIEW,youbuildgraphicalprogramscalledvirtualinstruments(VIs)insteadofwritingtext-basedprograms.Youquicklycreatefrontpaneluserinterfacesthatgiveyoutheinteractivecontrolofyoursystem.Toaddfunctionalitytotheuserinterface,youintuitivelyassembleblockdiagrams-anaturaldesignnotationforengineersandscientists.CreatetheFrontPanelOnthefrontpanelofyourVI,youplacethecontrolsanddatadisplaysforyoursystembyselectingobjectsfromtheControlspalette,suchasnumericdisplays,meters,gauges,thermometers,LEDs,charts,andgraphs.WhenyoucompleteandrunyourVI,youusethefrontpaneltocontrolyoursystemwhetheryoumoveaslide,zoominonagraph,orenteravaluewiththekeyboard.ConstructtheGraphicalBlockDiagramToprogramtheVI,youconstructtheblockdiagramwithoutworryingaboutthesyntacticaldetailsoftext-basedprogramminglanguages.Youdothisbyselectingobjects(icons)fromtheFunctionspaletteandconnectingthemtogetherwithwirestotransferdataamongblockdiagramobjects.Theseobjectsincludesimplearithmeticfunctions,advancedacquisitionandanalysisroutines,networkandfileI/Ooperations,andmore.DataflowProgrammingLabVIEWusesapatenteddataflowprogrammingmodelthatfreesyoufromthelineararchitectureoftext-basedprogramminglanguages.BecausetheexecutionorderinLabVIEWisdeterminedbytheflowofdatabetweennodes,andnotbysequentiallinesoftext,youcancreateblockdiagramsthat第5页executemultipleoperationsinparallel.Consequently,LabVIEWisamultitaskingsystemcapableofrunningmultipleexecutionthreadsandmultipleVIsinparallel.ModularityandHierarchyLabVIEWVIsaremodularindesign,soanyVIcanrunbyitselforaspartofanotherVI.YoucanevencreateiconsforyourownVIs,soyoucandesignahierarchyofVIsthatserveasapplicationbuildingblocks.Youcanmodify,interchange,andcombinethemwithotherVIstomeetyourchangingapplicationneeds.GraphicalCompilerInmanyapplications,executionspeediscritical.LabVIEWistheonlygraphicalprogrammingsystemwithacompilerthatgeneratesoptimizedcodewithexecutionspeedscomparabletocompiledCprograms.YoucanevenusetheLabVIEWprofilertoanalyseandoptimizetime-criticaloperations.Consequently,youincreaseyourproductivitywithgraphicalprogrammingwithoutsacrificingexecutionspeed.MeasurementsandMathematicsLabVIEWincludesavarietyofothermeasurementanalysistools.Examplesincludecurvefitting,signalgeneration,peakdetection,andprobabilityandstatistics.MeasurementanalysisfunctionscandeterminesignalcharacteristicssuchasDC/RMSlevels,totalharmonicdistortion(THD),impulseresponse,frequencyresponse,andcross-powerspectrum.LabVIEWuserscanalsodeploynumericaltoolsforsolvingdifferentialequations,optimization,rootfinding,andothermathematicalproblems.Inaddition,youcanextendthesebuilt-incapabilitiesbyenteringMATLABorHIQscriptsdirectlyinyourLabVIEWprograms.Forchartingandgraphing,youcanrelyonthebuilt-inLabVIEW2Dand3Dvisualizationtools.2DtoolsincludefeaturessuchasautoscalingXandYranges,reconfigurableattributes(point/linestyles,colors,andmore)andcursors,MicrosoftWindowsuserscanemployOpenGL-based3Dgraphsandthendynamicallyrotate,zoom,andpanthesegraphswiththemouse.DevelopmentSystemTheLabVIEWProfessionalDevelopmentSystemfacilitatesthedevelopment第6页ofhigh-end,sophisticatedinstrumentationsystemsfordevelopersworkinginteams,usersdevelopinglargesuitesofVIs,orprogrammersneedingtoadheretostringentqualitystandards.BuiltontheFullDevelopmentSystem,theProfessionalDevelopmentSystemalsoincludestheLabVIEWApplicationBuilderforbuildingstand-aloneexecutablesandsharedlibraries(DLLs）andcreatingdistributionkits.Inaddition,thedevelopmentsystemfurnishessourcecodecontroltoolsandoffersutilitiesforquantitativelymeasuringthecomplexityofyourapplications.Withgraphicaldifferencing,youcanquicklyidentifybothcosmeticandfunctionaldifferencesbetweentwoLabVIEWapplications.WeincludeprogrammingstandardsandstyleguidesthatprovidedirectionforconsistentLabVIEWprogrammingmethodology.ThesystemalsocontainsqualitystandardsdocumentsthatdiscussthestepsLabVIEWusersmustfollowtomeetinternalregulationsorFDAapproval.TheProfessionalDevelopmentSystemoperatesonWindows2000/NT/Me/9x,MacOS,HP-UX,andLinux.LabVIEWFullDevelopmentSystemTheLabVIEWFullDevelopmentSystemequipsyouwithallofthetoolsyouneedtodevelopinstrumentationsystems.ItincludesGPIB,VISA,VXI,RS-232,DAQ,andinstrumentdriverlibrariesfordataacquisitionandinstrumentcontrol.ThemeasurementanalysisaddDC/RMSmeasurements,singletoneanalysis,harmonicdistortionanalysis,SINADanalysis,limittesting,signalgenerationcapabilities,signalprocessing,digitalfiltering,windowing,curvefitting,statistics,andamyriadoflinearalgebraandmathematicalfunctions.ThedevelopmentsystemalsoprovidesfunctionsfordirectaccesstoDLLs,ActiveX,andotherexternalcode.OtherfeaturesofthesystemincludeWebpublishingtools,advancedreportgenerationtools,theabilitytocallMATLABandHiQscripts,3Dsurface,line,andcontourgraphs,andcustomgraphicsandanimation.TheFullDevelopmentSystemoperatesonWindows2000/NT/Me/9x,MacOS,HP-UX,andLinux.LabVIEWBasePackageUsetheLabVIEWBasePackage,theminimumLabVIEWconfiguration,fordevelopingdataacquisitionandanalysis,instrumentcontrol,andbasicdatapresentation.TheBasePackageoperatesonWindows2000/NT/Me/9x.DebugLicenseforLabVIEW第7页IfyoudeployLabVIEWapplications,includingLabVIEWtestsforusewithTestStand,thedebuglicenseallowsyoutoinstalltheLabVIEWdevelopmentsystemonthetargetmachinessoyoucanstepintoyourtestcodeforcompletetestdebugging.Thislicenseisnotintendedforprogramdevelopment.NationalInstrumentsLabVIEWisagraphicalprogramminglanguagethathasitsrootsinautomationcontrolanddataacquisition.Itsgraphicalrepresentation,similartoaprocessflowdiagram,wascreatedtoprovideanintuitiveprogrammingenvironmentforscientistsandengineers.Thelanguagehasmaturedoverthelast20yearstobecomeageneralpurposeprogrammingenvironment.LabVIEWhasseveralkeyfeatureswhichmakeitagoodchoiceinanautomationenvironment.Theseincludesimplenetworkcommunication,turnkeyimplementationofcommoncommunicationprotocols(RS232,GPIB,etc.),powerfultoolsetsforprocesscontrolanddatafitting,fastandeasyuserinterfaceconstruction,andanefficientcodeexecutionenvironment.Wediscussthemeritsofthelanguageandprovideanexampleapplicationsuitewrittenin-housewhichisusedinintegratingandcontrollingautomationplatforms.NILabVIEWasaPlatformforAutomationandInstrumentationOurexperiencecreatingbenchtopinstrumentationandintegratedautomationsystemshasvalidatedourchoiceofLabVIEWasanappropriatetool.LabVIEWenablesrapiddevelopmentoffunctionallyrichapplicationsappropriateforbothbenchtopapplicationsandlargerintegratedsystems.Onmanyoccasionswehavefoundthatprojectrequirementsareinitiallyilldefinedorchangeasnewmeasurementsornewassaysaredeveloped.Thereareseveralkeyfeaturesofthelanguagethatmakeitparticularlyusefulinanautomationenvironmentforcreatingapplicationstocontrolandintegrateinstrumentation,manageprocessflow,andenabledataacquisition.TurnkeyMeasurementandControlFunctionLabVIEWwasoriginallydevelopedforscientistsandengineers.ThelanguageincludesarichsetofprocesscontrolanddataanalysisfunctionsaswellasCOM,.NET,andsharedDLLsupport.Outofthebox,itprovidesturnkeysolutionstoavarietyofcommunicationprotocolsincludingRS232,GPIB,andTCP/IP.ControlstructuressuchastimedWhileLoopsallow第8页synchronizedandtimeddataacquisitionfromavarietyofhardwareinterfacessuchasPCI,USB,andPXI.DataSocketandVIServerDeploymentofanintegratedsystemwithmultiplecontrolcomputersrequirestheautomationcontrolapplicationtocommunicateremotelywithinstrumentdriversexistingonremotecomputers.LabVIEWsupportsadistributedarchitecturebyvirtueofenablingseamlessnetworkcommunicationthroughtechnologiessuchasVIServerandDSTP(datasocketstransferprotocol).DSTPisanapplicationlayerprotocolsimilartohttpbasedonTransmissionControlProtocol/InternetProtocol(TCP/IP).Datasocketsalloweasytransferofdatabetweenremotecomputerswithbasicreadandwritefunctions.ThroughVIservertechnology,functioncallscanbemadetoVIsresidingonremotecomputersasthoughtheyareresidingonthelocalcomputer.BothDatasocketsandVIservercanbeconfiguredtocontrolaccessesprivileges.SimpleUserInterface(UI)ImplementationInadditiontocommoninterfacecontrolssuchastextboxes,menurings,andcheck-boxes,LabVIEWprovidesarichsetofUIcontrols(switches,LEDs,gauges,arraycontrols,etc.)thatarepertinenttolaboratoryequipment.ThesehavetheiroriginsinLabVIEWslaboratoryrootsandhelpindevelopmentofinterfaceswhichgivescientistsaclearunderstandingofasystemsstate.LabVIEWsupportsUIconceptsincludingsubpanels(similartotheMultipleDocumentInterface),splitterbars,andXControls(analogoustoOCXcontrols).MultithreadedProgrammingEnvironmentTheinherentparallelenvironmentofLabVIEWisextremelyusefulinthecontroloflaboratoryequipment.FunctionscanhavemultiplecontinuousWhileLoopswhereoneloopisacquiringdatarapidlyandtheotherloopprocessesthedataatamuchslowerrate.Implementingsuchaparadigminotherlanguagesrequirestriggeringanindependentfunctionthreadforeachprocessanddevelopinglogictomanagesynchronization.ThroughtimedWhileLoops,multipleindependentWhileLoopscanbeeasilysynchronizedtoprocessatadesiredperiodandphaserelativetooneanother.LabVIEWallowsinvoking第9页multipleinstancesofthesamefunctionwitheachmaintainingitsowndataspace.Forinstance,wecoulddragmanyinstancesoftheMeansub-VIontotheblockdiagraminFigure1bandtheywouldallruninparallel,independentofoneanother.Tosynchronizeorenforcecontrolflowwithinthedataflowenvironment,LabVIEWalsoprovidesfunctionssuchasqueues,semaphores,andnotificationfunctions.ASerialportisaverygeneralcomputerequipmentcommunicationprotocol(dontandUnicersalSerialBusUniversalBusorUSBconfusion).MostcomputercontainstwobasedonRS-232serialport.Aserialportisalsoinstrumentationequipmentgeneralcommunicationprotocol,manyGPIBcompatibledeviceswithRS-232alsomouth.Atthesametimeserialcommunicationcanalsobeusedtoobtaintheremotedataacqueisitiondevice.Theconceptofserialcommunicationisverysimple,accordingtoaserialport(bit)sendandreceivebytes.Althoughthaninbytes(anuploadedfileparallelcommunicationisslow,butintheuseofaserialportcansenddatalineatthesametimewiththeotheronelinereceivedata.itissimpleandcanrealizethelongdistancecommunication.ForexampleIEEE488definitionparallelstateoftraffic,regulationlineequipmentshallnotexceedthetotaloften20metersandbetweenanytwoofthelengthoftheequipmentisnomorethan2meters,andforaserialportisconcerned),lengthupto1200m.Typicall.AserialportforASCIIcharaterstransmission.Communicationusingthe3linecomplete:(1)groundlead,(2)tosend,(3)toreceive.Becauseisasynchronousserialcommunication,portcaninaroottosenddataandonlineinanotherrootonlinereceivedata.Otherlinesusedtoshakehands,butnotamust.Themostimportantparametersofserialcommunicationisbaudrate,databits,andstopbitsandparity.Fortwoforpopularport,theseparametersmustmatch:1,baudrate,thisisameasureoftheparametersofthecommunicationsspeed.Itsayseverysecondofthenumbersofbittransmission.Forexample300pottersayssend300biteveryseconds.Whenwetalkabouttheclockcycle,wemeansbaudrateforexampleifagreementneed4800baudratesoclockis4800HZ.Thismeansthatintheserialcommunicationdatasamplingratefor4800Hz.Usuallytelephonelineofbaudratefor14400288and36600.第10页Baudratecanbefargreaterthanthevalue,butbaudrateandisinverselyproportionaltothedistance.Highbaudrateoftenusedinplaceofverynearthecommunicationsbetweentheinstrument,atypicalexampleisGPIBequipmentcommunications.2.databits,itisthemeasureoftheactualcommunicationaparameter.Whenthecomputersendsapacket,theactualdatawontbeeight,standardvalueis5,7and8bits.Dependsonhowtosetupthetransferofinformationyouwant.Forexample,thestandardASCIIis0127(seven).ExtendedASCIIis0255(eight).Ifthedatausingthesimpletext(standardASCII),soeachpacketusesevendatadependsontheselectionofacommunicationprotocol,the“bag”referstoanycommunication.3andstopbits,usedtosaythelatestinasinglepackage.Thetypicalvalueis1,1.5andtwo.Sincethedataisinthetimingonatransmissionline,andeachdevicehasitsownclock,probablyinthecommunicationbetweentwosetsofequipmentinthesmallsynchronization.Sostopbitisnotjustsaidtheendoftransmission,andprovidetheopportunitytotheclocksynchronizationcomputercorrection.Applytostopbitsofdigits,themoredifferenttheclocksynchronizationoftolerance,thebiggerthedatatransferratebutalsomoreslowly.4,parityinserialcommunicationofdetectionofasimplewaywrong.Therearefourkindsofinspectionwrongway:accidentally,strange,highandlow.Ofcoursenoparitycantoo.ForIandcalibrationofstrangesituation,serialportswillsetparity(databitsofbehinda)withavaluetoensurethatthedatahaveaccidentallyoralogicshigh.Forexample,ifthedatais011,andsototheparitychecking,parityfor0,ensurethelogichighisevendigits.Ifbeoddcheck,checkdigita1,