電子與通信技術(shù)專業(yè)英語(yǔ)（第6版）課件 項(xiàng)目9 Virtual Instruments

劉騁蔡靜主編電子與通信技術(shù)專業(yè)英語(yǔ)（第6版）高職高專電子信息類“十三五”規(guī)劃教材EnglishonElectronicandTelecommunicationTechnology02UnitⅡElectronicInstrumentandProductsLesson9VirtualInstruments

UnitⅡNewWordsvirtual ['v?:t?u?l] adj.虛擬的hardware ['hɑ:dwe?] n.計(jì)算機(jī)硬件transform [tr?ns'f?:m] v.改變，改觀，變換transmit [tr?nz'mit] v.傳輸，傳送，發(fā)送interpreter [in't?:prit?] n.解釋者，翻譯器converter [k?n'v?:t?] n.變換器，換流器，變壓器，變頻器NewWordsimplementation [,implimen'tei?n] n.成就，貫徹，安裝啟用modular ['m?dj?l?] adj. 模塊化的monitor ['m?nit?] n.&vt.顯示屏，屏幕，

顯示器，監(jiān)測(cè)儀；監(jiān)視synchronization [,si?kr?nai'zei??n] n. 同一時(shí)刻，同步NewWordsbus [b?s] n. 總線Ethernet ['i:θ?net] n. 以太網(wǎng)Latency ['leit?nsi] n. 潛伏，潛在因素integrate ['intigreit] v. 使一體化，使集成instrumentation [,instr?men'tei??n]n. 儀器PhrasesandExpressionsADC（Analogue-to-DigitalConverter） 模數(shù)轉(zhuǎn)換器DAC（Digital-to-AnalogueConverter） 數(shù)模轉(zhuǎn)換器USBinterface USB接口CPU（CentralProcessingUnit）

中央處理單元scalewith 與……成比例Virtualinstrumentsarecomputerprogramsthatinteractwithrealworldobjectsbymeansofsensorsandimplementfunctionsofrealorimaginaryinstruments.Thesensorisusuallyasimplehardwarethatacquiresdatafromtheobject,transformsitintoelectricsignalsandtransmitstothecomputerforfurtherprocessing（asshowninFig.9-1）.Simplevirtualmeasuringinstrumentsjustacquireandanalysesdata,butmorecomplexvirtualinstrumentscommunicatewithobjectsinbothdirections.Lesson9VirtualInstrumentsChineseTranslationofTexts虛擬儀器是通過(guò)傳感器與真實(shí)世界物體進(jìn)行交互并完成真實(shí)或虛擬儀器功能的計(jì)算機(jī)程序。傳感器通常是一個(gè)簡(jiǎn)單的硬件，它從實(shí)物獲取數(shù)據(jù)，將其轉(zhuǎn)換成電子信號(hào)并傳輸?shù)接?jì)算機(jī)作進(jìn)一步處理（如圖9－1所示）。簡(jiǎn)單的虛擬測(cè)量?jī)x器只是獲取和分析數(shù)據(jù)，但更復(fù)雜的虛擬儀器能與物體進(jìn)行雙向通信。第9課

虛擬儀器ChineseTranslationofTextsRealworldsignalsareofanaloguenature,whileacomputerisadigitalinstrument;thereforethecomputerneedsalsointerpreters–analogue-to-digitalanddigital-to-analogueconvertersforcommunicationwiththeobject.ADCandDACboardsthatimplementthisfunctionininexpensivesystemsareusuallyplacedinsidethecomputer.CompactexternalADC/DACconverterswithUSBinterfacearealsobecomingpopular.ChineseTranslationofTexts現(xiàn)實(shí)世界的信號(hào)是模擬性質(zhì)的，而計(jì)算機(jī)是數(shù)字儀器；因此計(jì)算機(jī)與對(duì)象進(jìn)行通信時(shí)需要進(jìn)行轉(zhuǎn)譯——模-數(shù)和數(shù)-模轉(zhuǎn)換。在廉價(jià)的系統(tǒng)中，實(shí)現(xiàn)這一功能的模數(shù)轉(zhuǎn)換和模數(shù)轉(zhuǎn)換板通常內(nèi)置于計(jì)算機(jī)中。緊湊的外置帶USB接口的模數(shù)/數(shù)模轉(zhuǎn)換器的也越來(lái)越普及。ChineseTranslationofTextsLabVIEWisagraphicalprogramminglanguagefromNationalInstruments.LabVIEWprogramsarecalledvirtualinstrumentsoftenabbreviatedtoVIs.Eachvirtualinstrumenthastwocomponents,ablockdiagramandafrontpanel.Controlsandindicatorsonthefrontpanelallowanoperatortoinputdataintoorextractdatafromanalreadyrunningvirtualinstrument.ChineseTranslationofTexts

LabVIEW是NI公司的圖形化編程語(yǔ)言。通常把LabVIEW程序稱為虛擬儀器，縮寫(xiě)為VIs。每個(gè)虛擬儀器有兩個(gè)組成部分，框圖和前面板。前面板上的控制和指令允許操作員從一個(gè)已經(jīng)在運(yùn)行的虛擬儀器中輸入數(shù)據(jù)或提取數(shù)據(jù)。ChineseTranslationofTextsIntermsofperformance,LabVIEWincludesanactualcompilerthatproducesnativecodefortheCPUplatform,sothegraphicalcodeiscompiled,ratherthaninterpreted.ChineseTranslationofTexts在性能方面，LabVIEW包含一個(gè)為CPU平臺(tái)生成本地代碼的實(shí)際的編譯器，它編譯圖形代碼，而不僅僅是轉(zhuǎn)換。ChineseTranslationofTextsOneofthemainbenefitsofLabVIEWisthatpeoplewithlittleornopreviousprogrammingexperienceareabletoaccesshardwareinput/outputmorerapidlyandthroughahardwareabstractionsystem.Thisabstractionallowsisolationbetweenhardwareimplementationandsoftwaresolution.AtechniquewhichwithoutNationalInstrumentssoftwaredriverinterfacewouldbeextremelytimeconsuming.ChineseTranslationofTexts

LabVIEW的主要優(yōu)點(diǎn)之一是，有很少的或者根本沒(méi)有編程經(jīng)驗(yàn)的人都能夠很迅??速地訪問(wèn)硬件的輸入/輸出，以及通過(guò)硬件抽象系統(tǒng)。這個(gè)硬件抽象層允許硬件實(shí)現(xiàn)和軟件解決方案之間的隔離。沒(méi)有NI軟件驅(qū)動(dòng)程序接口的技術(shù)將是非常費(fèi)時(shí)的。

ChineseTranslationofTextsAnothervirtualinstrumentationcomponentismodularI/O,designedtoberapidlycombinedinanyorderorquantitytoensurethatvirtualinstrumentationcanbothmonitorandcontrolanydevelopmentaspect.Usingwell-designedsoftwaredriversformodularI/O,engineersandscientistsquicklycanaccessfunctionsduringconcurrentoperation.ChineseTranslationofTexts另一個(gè)虛擬儀器組件是模塊化的I/O，它被設(shè)計(jì)用來(lái)在任何命令或數(shù)量上迅速兼容，以確保虛擬儀器可以同時(shí)監(jiān)視和控制各個(gè)方面的發(fā)展。使用為模塊化的I/O精心設(shè)計(jì)的軟件驅(qū)動(dòng)程序，工程師和科學(xué)家可以在并行操作期間實(shí)現(xiàn)快速訪問(wèn)功能。ChineseTranslationofTextsThethirdvirtualinstrumentationelement–usingcommercialplatforms,oftenenhancedwithaccuratesynchronization–ensuresthatvirtualinstrumentationtakesadvantageoftheverylatestcomputercapabilitiesanddatatransfertechnologies.Thiselementdeliversvirtualinstrumentationonalong-termtechnologybasethatscaleswiththehighinvestmentsmadeinprocessors,buses,andmore.ChineseTranslationofTexts虛擬儀器的第三個(gè)要素——使用商業(yè)平臺(tái)，這通常使得精確同步得到提高——確保該虛擬儀器采用了最新的計(jì)算機(jī)功能和數(shù)據(jù)傳輸技術(shù)。這個(gè)元素保證了虛擬儀器在高投資規(guī)模的處理器，總線技術(shù)上的技術(shù)水平。ChineseTranslationofTextsVirtualinstrumentationsystemsfrequentlyuseEthernetforremotetestsystemcontrol,distributedI/O,andenterprisedatasharing.Ethernetprovidesalow-cost,moderate-throughputmethodforexchangingdataandcontrolcommandsoverdistances.However,duetoitspacket-basedarchitecture,Ethernetisnotdeterministicandhasrelativelyhighlatency.Forsomeapplications,suchasinstrumentationsystems,thelackofdeterminismandhighlatencymakeEthernetapoorchoiceforintegratingadjacentI/Omodules.ThesesituationsarebetterservedwithadedicatedbussuchasPXI,VXI,orGPIB（asshowninFig.9-2）.ChineseTranslationofTexts虛擬儀器系統(tǒng)在進(jìn)行遠(yuǎn)程測(cè)試系統(tǒng)控制，分布式I/O和企業(yè)數(shù)據(jù)共享時(shí)，經(jīng)常利用以太網(wǎng)。以太網(wǎng)為數(shù)據(jù)交換和遠(yuǎn)距離指令控制提供了一個(gè)低成本和中等吞吐量的方法。然而，由于其基于分組的架構(gòu)，以太網(wǎng)具有不確定性，并有較高的延遲。對(duì)于某些應(yīng)用，如儀表系統(tǒng)，由于以太網(wǎng)缺乏確定性和高延遲，使其在集成相鄰的I/O模塊時(shí)不是一種好的選擇。這種情況下最好選擇專用總線，如PXI，VXI或GPIB（如圖9-2所示）。ChineseTranslationofTextsNotesVirtualinstrumentsarecomputerprogramsthatinteractwithrealworldobjectsbymeansofsensorsandimplementfunctionsofrealorimaginaryinstruments.

realworldobjects：真實(shí)世界物體，現(xiàn)實(shí)世界中的物體。虛擬儀器是通過(guò)傳感器與真實(shí)世界物體進(jìn)行交互并完成真實(shí)或虛擬儀器功能的計(jì)算機(jī)程序。1NotesRealworldsignalsareofanaloguenature,whileacomputerisadigitalinstrument.Realworldsignals：現(xiàn)實(shí)世界的信號(hào)現(xiàn)實(shí)世界的信號(hào)是模擬信號(hào)，而計(jì)算機(jī)是數(shù)字儀器。2Notesthereforethecomputerneedsalsointerpreters–analogue-to-digitalanddigital-to-analogueconvertersforcommunicationwiththeobject.

analogue-to-digital：模擬-數(shù)字，從模擬到數(shù)字

digital-to-analogueconverter：數(shù)字-模擬轉(zhuǎn)換器因此計(jì)算機(jī)與對(duì)象進(jìn)行通信時(shí)需要進(jìn)行轉(zhuǎn)譯－模數(shù)轉(zhuǎn)換和數(shù)模轉(zhuǎn)換，與被測(cè)對(duì)象進(jìn)行通信。3NotesLabVIEWisagraphicalprogramminglanguagefromNationalInstruments.LabVIEWprogramsarecalledvirtualinstrumentsoftenabbreviatedtoVIs.LabVIEW：是美國(guó)國(guó)家儀器公司（NationalInstrumentsNI）1986年推出的圖形化系統(tǒng)設(shè)計(jì)軟件，現(xiàn)今，數(shù)以百萬(wàn)的工程師和科學(xué)家可以使用LabVIEW來(lái)構(gòu)建他們的測(cè)試、測(cè)量與控制系統(tǒng)。Vis：virtualinstrument虛擬儀器技術(shù)就是利用高性能的模塊化硬件，結(jié)合高效靈活的軟件來(lái)完成各種測(cè)試、測(cè)量和自動(dòng)化的應(yīng)用。

LabVIEW是NI公司的圖形化編程語(yǔ)言。通常把LabVIEW程序也稱為虛擬儀器，縮寫(xiě)為VIs。4NotesAnothervirtualinstrumentationcomponentismodularI/O.

I/O：input/output的縮寫(xiě)，即輸入輸出端口。另一個(gè)虛擬儀器組件是模塊化的I/O。5NotesThesesituationsarebetterservedwithadedicatedbussuchasPXI,VXI,orGPIB.PXI：(PCIextensionsforInstrumentation，面向儀器系統(tǒng)的PCI擴(kuò)展)是一種堅(jiān)固的基于PC的測(cè)量和自動(dòng)化平臺(tái)。VXI：CiscoVirtualizationExperienceInfrastructure虛擬化體驗(yàn)基礎(chǔ)架構(gòu)GPIB：GeneralPurposeInterfaceBus通用接口總線這種情況下最好選擇專用總線，如PXI，VXI或GPIB。6Exercises1.WriteT(True)orF(false)besidethefollowingstatementsaboutthetext.a.Thesensorisusuallyasimplesoftwarethatacquiresdatafromtheobject,transformsitintoelectricsignalsandtransmitsittothecomputerforfurtherprocessing.b.Realworldsignalsareofdigitalnature,whileacomputerisaanalogueinstrument.c.ADCandDACboardsthatimplementthisfunctioninexpensivesystemsareusuallyplacedinsidethecomputer.d.LabVIEWisagraphicalprogramminglanguagefromNationalInstruments.e.Controlsandindicatorsonthefrontpanelallowanoperatortoinputdataintoorextractdatafromanalreadyrunningvirtualinstrument.Exercises1.WriteT(True)orF(false)besidethefollowingstatementsaboutthetext.a.Thesensorisusuallyasimplesoftwarethatacquiresdatafromtheobject,transformsitintoelectricsignalsandtransmitsittothecomputerforfurtherprocessing.b.Realworldsignalsareofdigitalnature,whileacomputerisaanalogueinstrument.c.ADCandDACboardsthatimplementthisfunctioninexpensivesystemsareusuallyplacedinsidethecomputer.d.LabVIEWisagraphicalprogramminglanguagefromNationalInstruments.e.Controlsandindicatorsonthefrontpanelallowanoperatortoinputdataintoorextractdatafromanalreadyrunningvirtualinstrument.F

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