交通燈畢業(yè)論文英文資料翻譯

畢業(yè)論文英文資料翻譯系別：專業(yè)：班級:姓名：學號：IntroductionofProgrammablecontrollersFromasimpleheritage，theseremarkablesystemshaveevolvedtonotonlyreplaceelectromechanicaldevices，buttosolveanever—increasingarrayofcontrolproblemsinbothprocessandnonprocessindustries.Byallindications,thesemicroprocessorpoweredgiantswillcontinuetobreaknewgroundintheautomatedfactoryintothe1990s.HISTORYInthe1960s，electromechanicaldevicesweretheorderofthedayassfarascontrolwasconcerned。Thesedevices，commonlyknownasrelays，werebeingusedbythethousandstocontrolmanysequential—typemanufacturingprocessesandstand—alongmachines.Manyoftheserelayswereinuseinthetransportationindustry,morespecifically，theautomotiveindustry.Theserelaysusedhundredsofwiresandtheirinterconnectionstoeffectacontrolsolution.Theperformanceofarelaywasbasicallyreliable—atleastasasingledevice.Butthecommonapplicationsforrelaypanelscalledfor300to500ormorerelays，andthereliabilityandmaintenanceissuesassociatedwithsupportingthesepanelsbecameaverygreatchallenge。Costbecameanotherissue，forinspiteofthelowcostoftherelayitself,theinstalledcostofthepanelcouldbequitehigh。Thetotalcostincludingpurchasedparts，wiring,andinstallationlabor,couldrangefrom＄30~＄50perrelay。Tomakemattersworse,theconstantlychangingneedsofaprocesscalledforrecurringmodificationsofacontrolpanel.Withrelays，thiswasacostlyprospect,asitwasaccomplishedbyamajorrewiringeffortonthepanel.Inadditionthesechangesweresometimespoorlydocumented,causingasecond—shiftmaintenancenightmaremonthslater。Inlightofthis，itwasnotuncommontodiscardanentirecontrolpanelinfavorofanewonewiththeappropriatecomponentswiredinamannersuitedforthenewprocess.Addtothistheunpredictable,andpotentiallyhigh，costofmaintainingthesesystemsasonhigh-volumemotorvehicleproductionlines,anditbecameclearthatsomethingwasneededtoimprovethecontrolprocess–tomakeitmorereliable,easiertotroubleshoot,andmoreadaptabletochangingcontrolneeds。Thatsomething，inthelate1960s,wasthefirstprogrammablecontroller。Thisfirst‘revolutionary’systemwandevelopedasaspecificresponsetotheneedsofthemajorautomotivemanufacturersintheUnitedStates.Theseearlycontrollers，orprogrammablelogiccontrollers(PLC),representedthefirstsystemsthat1couldbeusedonthefactoryfloor,2couldhavethere‘logic’changedwithoutextensiverewiringorcomponentchanges，and3wereeasytodiagnoseandrepairwhenproblemsoccurred.Itisinterestingtoobservetheprogressthathasbeenmadeinthepast15yearsintheprogrammablecontrollerarea.Thepioneerproductsofthelate1960smusthavebeenconfusingandfrighteningtoagreatnumberofpeople。Forexample，whathappenedtothehardwiredandelectromechanicaldevicesthatmaintenancepersonnelwereusedtorepairingwithhandtools？Theywerereplacedwith‘computers’disguisedaselectronicsdesignedtoreplacerelays.Eventheprogrammingtoolsweredesignedtoappearasrelayequivalentpresentations.Wehavetheopportunitynowtoexaminethepromise,inretrospect，thattheprogrammablecontrollerbroughttomanufacturing。AllprogrammablecontrollersconsistofthebasicfunctionalblocksshowninFig.10。1.We’llexamineeachblocktounderstandtherelationshiptothecontrolsystem。Firstwelookatthecenter,asitistheheart(oratleastthebrain）ofthesystem。Itconsistsofamicroprocessor,logicmemoryforthestorageoftheactualcontrollogic，storageorvariablememoryforusewithdatathatwillordinarilychangeasafunctionpowerfortheprocessorandmemory.NextcomestheI/Oblock.ThisfunctiontakesthecontrollevelsignalsfortheCPUandconvertsthemtovoltageandcurrentlevelssuitableforconnectionwithfactorygradesensorsandactuators.TheI/Otypecanrangefromdigital（discreteoron/off)，analog(continuouslyvariable),oravarietyofspecialpurpose‘smart'I/Owhicharededicatedtoacertainapplicationtask。Theprogrammerisshownhere,butitisnormallyusedonlytoinitiallyconfigureandprogramasystemandisnotrequiredforthesystemtooperate。Itisalsousedintroubleshootingasystem,andcanprovetobeavaluabletoolinpinpointingtheexactcauseofaproblem.ThefielddevicesshownhererepresentthevarioussensorsandactuatorsconnectedtotheI/O.Thesearethearms，legs，eyes,andearsofthesystem，includingpushbuttons，limitswitches，proximityswitches，photosensors,thermocouples，RTDS，positionsensingdevices，andbarcodereaderasinput；andpilotlights,displaydevices，motorstarters，DCandACdrives,solenoids，andprintersasoutputs。Nosingleattemptcouldcoveritsrapidlychangingscope,butthreebasiccharacteristicscanbeexaminedtogiveclassifyanindustrialcontroldeviceasaprogrammablecontroller。(1）Itsbasicinternaloperationistosolvelogicfromthebeginningofmemorytosomespecifiedpoint,suchasendofmemoryorendofprogram。Oncetheendisreached，theoperationbeginsagainatthebeginningofmemory.Thisscanningprocesscontinuesfromthetimepowerissuppliedtothetimeititremoved.(2)Theprogramminglogicisaformofarelayladderdiagram。Normallyopen，normallyclosedcontacts,andrelaycoilsareusedwithinaformatutilizingaleftandarightverticalrail.Powerflow（symbolicpositiveelectronflow）isusedtodeterminewhichcoiloroutputsareenergizedordeenergized.（3）Themachineisdesignedfortheindustrialenvironmentfromitsbasicconcept；thisprotectionisnotaddedatalaterdate.TheindustrialenvironmentincludesunreliableACpower,hightemperatures（0to60degreeCelsius)，extremesofhumidity,vibrations,RFnoise,andothersimilarparameters.GeneralapplicationareasTheprogrammablecontrollerisusedinawidevarietyofcontrolapplicationstoday,manyofwhichwerenoteconomicallypossiblejustafewyearsago.Thisistruefortwogeneralreasons:1therecosteffectiveness(thatis，thecostperI/Opoint）hasimproveddramaticallywiththefallingpricesofmicroprocessorsandrelatedcomponents，and2theabilityofthecontrollertosolvecomplexcomputationandcommunicationtaskshasmadeitpossibletouseitwhereadedicatedcomputerwaspreviouslyused.Applicationsforprogrammablecontrollerscanbecategorizedinanumberofdifferentways,includinggeneralandindustrialapplicationcategories。Butitisimportanttounderstandtheframeworkinwhichcontrollersarepresentlyunderstoodandusedsothatthefullscopeofpresentandfutureevolutioncanbeexamined。Itisthroughthepowerofapplicationsthatcontrollerscanbeseenintheirfulllight。Industrialapplicationsincludemanyinbothdiscretemanufacturingandprocessindustries。Automotiveindustryapplications,thegenesisoftheprogrammablecontroller,continuetoprovidethelargestbaseofopportunity.Otherindustries，suchasfoodprocessingandutilities，providecurrentdevelopmentopportunities。Therearefivegeneralapplicationareasinwhichprogrammablecontrollersareused.Atypicalinstallationwilluseoneormoreoftheseintegratedtothecontrolsystemproblem.Thefivegeneralareasareexplainedbrieflybelow.DescriptionTheAT89C51isalow—power,high—performanceCMOS8—bitmicrocomputerwith4KbytesofFlashprogrammableanderasablereadonlymemory(PEROM).ThedeviceismanufacturedusingAtmel’shigh-densitynonvolatilememorytechnologyandiscompatiblewiththeindustry-standardMCS—51instructionsetandpinout.Theon—chipFlashallowstheprogrammemorytobereprogrammedin-systemorbyaconventionalnonvolatilememoryprogrammer。Bycombiningaversatile8—bitCPUwithFlashonamonolithicchip,theAtmelAT89C51isapowerfulmicrocomputerwhichprovidesahighly—flexibleandcost-effectivesolutiontomanyembeddedcontrolapplications。FunctioncharacteristicTheAT89C51providesthefollowingstandardfeatures：4KbytesofFlash,128bytesofRAM,32I/Olines,two16—bittimer/counters，afivevectortwo-levelinterruptarchitecture，afullduplexserialport,on-chiposcillatorandclockcircuitry.Inaddition,theAT89C51isdesignedwithstaticlogicforoperationdowntozerofrequencyandsupportstwosoftwareselectablepowersavingmodes。TheIdleModestopstheCPUwhileallowingtheRAM,timer/counters,serialportandinterruptsystemtocontinuefunctioning.ThePower—downModesavestheRAMcontentsbutfreezestheoscillatordisablingallotherchipfunctionsuntilthenexthardwarereset。PinDescriptionVCC：Supplyvoltage。GND:Ground。Port0:Port0isan8—bitopen—drainbi-directionalI/Oport。Asanoutputport,eachpincansinkeightTTLinputs。When1sarewrittentoport0pins，thepinscanbeusedashighimpedanceinputs.Port0mayalsobeconfiguredtobethemultiplexedloworderaddress/databusduringaccessestoexternalprogramanddatamemory。InthismodeP0hasinternalpullups.Port0alsoreceivesthecodebytesduringFlashprogramming，andoutputsthecodebytesduringprogramverification.Externalpullupsarerequiredduringprogramverification。Port1Port1isan8-bitbi-directionalI/Oportwithinternalpullups。ThePort2Port2isan8-bitbi—directionalI/Oportwithinternalpullups。ThePort3Port3isan8-bitbi—directionalI/Oportwithinternalpullups.ThePort3alsoreceivessomecontrolsignalsforFlashprogrammingandverification.RSTResetinput。Ahighonthispinfortwomachinecycleswhiletheoscillatorisrunningresetsthedevice.ALE/PROGAddressLatchEnableoutputpulseforlatchingthelowbyteoftheaddressduringaccessestoexternalmemory。Thispinisalsotheprogrampulseinput(PROG)duringFlashprogramming。InnormaloperationALEisemittedataconstantrateof1/6theoscillatorfrequency，andmaybeusedforexternaltimingorclockingpurposes。Note,however，thatoneALEpulseisskippedduringeachaccesstoexternalDataMemory。Ifdesired,ALEoperationcanbedisabledbysettingbit0ofSFRlocation8EH.Withthebitset,ALEisactiveonlyduringaMOVXorMOVCinstruction。Otherwise，thepinisweaklypulledhigh.SettingtheALE-disablebithasnoeffectifthemicrocontrollerisinexternalexecutionmode。PSENProgramStoreEnableisthereadstrobetoexternalprogrammemory。WhentheAT89C51isexecutingcodefromexternalprogrammemory,PSENisactivatedtwiceeachmachinecycle,exceptthattwoPSENactivationsareskippedduringeachaccesstoexternaldatamemory。EA/VPPExternalAccessEnable.EAmustbestrappedtoGNDinordertoenablethedevicetofetchcodefromexternalprogrammemorylocationsstartingat0000HuptoFFFFH。Note,however，thatiflockbit1isprogrammed，EAwillbeinternallylatchedonreset.EAshouldbestrappedtoVCCforinternalprogramexecutions。Thispinalsoreceivesthe12-voltprogrammingenablevoltage（VPP）duringFlashprogramming，forpartsthatrequire12-voltVPP。XTAL1Inputtotheinvertingoscillatoramplifierandinputtotheinternalclockoperatingcircuit.XTAL2Outputfromtheinvertingoscillatoramplifier。OscillatorCharacteristicsXTAL1andXTAL2aretheinputandoutput，respectively,ofaninvertingamplifierwhichcanbeconfiguredforuseasanon-chiposcillator，asshowninFigure1。Eitheraquartzcrystalorceramicresonatormaybeused。Todrivethedevicefromanexternalclocksource，XTAL2shouldbeleftunconnectedwhileXTAL1isdrivenasshowninFigure2.Therearenorequirementsonthedutycycleoftheexternalclocksignal,sincetheinputtotheinternalclockingcircuitryisthroughadivide-by-twoflip—flop,butminimumandmaximumvoltagehighandlowtimespecificationsmustbeobserved。Figure1.OscillatorConnectionsFigure2。ExternalClockDriveConfigurationIdleModeInidlemode,theCPUputsitselftosleepwhilealltheonchipperipheralsremainactive.Themodeisinvokedbysoftware。Thecontentoftheon—chipRAMandallthespecialfunctionsregistersremainunchangedduringthismode.Theidlemodecanbeterminatedbyanyenabledinterruptorbyahardwarereset.Itshouldbenotedthatwhenidleisterminatedbyahardwarereset，thedevicenormallyresumesprogramexecution,fromwhereitleftoff,uptotwomachinecyclesbeforetheinternalresetalgorithmtakescontrol.On—chiphardwareinhibitsaccesstointernalRAMinthisevent,butaccesstotheportpinsisnotinhibited.ToeliminatethepossibilityofanunexpectedwritetoaportpinwhenIdleisterminatedbyreset,theinstructionfollowingtheonethatinvokesIdleshouldnotbeonethatwritestoaportpinortoexternalmemory。Power—downModeInthepower-downmode,theoscillatorisstopped,andtheinstructionthatinvokespower—downisthelastinstructionexecuted.Theon—chipRAMandSpecialFunctionRegistersretaintheirvaluesuntilthepower-downmodeisterminated.Theonlyexitfrompower—downisahardwarereset.ResetredefinestheSFRsbutdoesnotchangetheon-chipRAM.TheresetshouldnotbeactivatedbeforeVCCisrestoredtoitsnormaloperatinglevelandmustbeheldactivelongenoughtoallowtheoscillatortorestartandstabilize.ProgramMemoryLockBitsOnthechiparethreelockbitswhichcanbeleftunprogrammed（U）orcanbeprogrammed（P)toobtaintheadditionalfeatureslistedinthetablebelow。Whenlockbit1isprogrammed，thelogiclevelattheEApinissampledandlatchedduringreset.Ifthedeviceispoweredupwithoutareset，thelatchinitializestoarandomvalue，andholdsthatvalueuntilresetisactivated。ItisnecessarythatthelatchedvalueofEAbeinagreementwiththecurrentlogiclevelatthatpininorderforthedevicetofunctionproperly介紹可編程控制器從一個簡單的遺產(chǎn),這顯著的系統(tǒng)已經(jīng)進化到不僅取代機電設備，而是為了解決日益增加的一系列控制問題在這兩種過程和nonprocess行業(yè)。通過所有的適應癥,這些微處理器巨人將繼續(xù)為動力的新局面,到20世紀90年代的自動化的工廠。歷史：在20世紀60年代,機電設備的議事日程的屁股遠為控制問題越來越受到關(guān)注.這些設備，俗稱繼電器、正被利用著成千上萬的制造過程和控制多個sequential—typestand-along機器.許多這些繼電器被應用在交通行業(yè)，更確切的說,汽車工業(yè)。這些繼電器使用他們數(shù)以百計的電線和連接到調(diào)用控制解決方案。接力的性能基本可靠-—至少是一個單一的裝置。但是共同申請繼電器板呼吁300-500或更多的繼電器、可靠性及維護和支持這些電池板相關(guān)的問題變得非常巨大的挑戰(zhàn)。成本成為了另一個問題，盡管的低成本的圣火傳遞本身，面板安裝成本可能會相當高.總成本包括采購部件、配線和安裝的勞動力，可以范圍從＄30~50美元的傳遞。更糟的是，不斷轉(zhuǎn)變的需要,這個過程稱為為復發(fā)性修改中的一個控制面板.用繼電器,這是一個昂貴的前景所完成的，因為它是一個主要的電路重組的努力,在面板。除了這些改變是有時差,導致second—shift記錄維護噩夢月之后。由此可知，這不是希有報廢整個控制面板贊成一種新的以適當?shù)牟考b上了一個方式適合于新工藝。如果再加上不可預知的,潛在的高成本、維持這些系統(tǒng)在大批量汽車生產(chǎn)線,顯然,是有什么東西需要，提高了控制的過程--使它更可靠、更容易解決，并更加適應變化控制的需要。這東西,在60年代末期,是第一個可編程控制器.這第一次的革命的系統(tǒng)廣域網(wǎng)路發(fā)展為一個特定的反應的需要大汽車制造商在美國.這些早期的控制器，或可編程邏輯控制器（PLC)為代表的第一個系統(tǒng),1可以用在我的工廠里，2個可能有“邏輯電路重組的改變或組件沒有廣泛的變化，并對3例診斷和修理時容易出現(xiàn)的問題。有趣的是，要觀察的進展，已經(jīng)在過去的15年的可編程控制器的區(qū)域。先鋒國際的60年代后期的產(chǎn)品一定是令人困惑的和令人恐懼的很多的人。例如，發(fā)生了什么事，多樣和機電設備維修人員被用來修復手工具嗎?他們被替換的計算機的偽裝成電子設計來取代繼電器。即使是編程工具被設計來出現(xiàn),因為傳遞等價的報告?，F(xiàn)在我們有機會來檢查我們的承諾，現(xiàn)在回想起來,那可編程控制器帶到制造。所有的可編程控制器構(gòu)成的基本功能塊如下：我們將審查每個街區(qū)去理解這個關(guān)系到控制系統(tǒng).先看看我們的中心，因為它是心(或至少是大腦）系統(tǒng)。它由一個微處理器、邏輯記憶存放的實際控制邏輯、儲存或變量的內(nèi)存使用數(shù)據(jù)通常改變?yōu)橐粋€函數(shù)權(quán)為處理器和記憶。接下來的I/O街區(qū)。這個函數(shù)采取控制水平信號的CPU和將他們轉(zhuǎn)換成電壓和電流,適用于連接級別與工廠級傳感器和執(zhí)行器的自診斷。I/O型的范圍可以從數(shù)字（離散型或開/關(guān))，模擬(連續(xù)變量）,或者其他各種特殊用途的聰明的I/O專門某個特定應用的任務。這里展示的是程序員的,但是它通常只用于最初配置和程序是一個系統(tǒng),而不需要系統(tǒng)的操作。它也被用于故障診斷系統(tǒng),并不能證明是一種寶貴的工具,在查明問題的確切原因仍在調(diào)查中.這里展示的現(xiàn)場設備代表各種傳感器和執(zhí)行器連接到I/O。這些是胳膊、腿、眼睛、耳朵的系統(tǒng),包括按鈕、限位開關(guān),接近開關(guān),photosensors、熱電偶、取得、位置傳感裝置，條形碼閱讀器作為神經(jīng)網(wǎng)絡的輸入，導向燈，顯示設備，電機起動器、直流和交流驅(qū)動、電磁閥、打印機作為輸出。沒有一種單一的嘗試可能包括它的快速變化的范圍,但三個基本特征可以查看給分類工業(yè)控制裝置作為一個可編程控制器。（1)其基本的內(nèi)部經(jīng)營是解決邏輯從一開始的記憶體的一些特殊點，如內(nèi)存或年底結(jié)束程序。一旦最終達成共識,操作將再一次開始之初的記憶。該掃描過程一直持續(xù)時間從電力供應到它移開.（2）編程邏輯是一種傳遞梯形圖。常開,常閉觸點和繼電器線圈是范圍內(nèi)使用的格式，利用左和右垂直軌道。功率流(象征性的正電子流）是用來確定哪些卷或輸出或充滿活力。(3)這臺機器是專為工業(yè)環(huán)境從其基本概念，這種保護是沒有添加在稍后的日期。工業(yè)環(huán)境包括不可靠的交流電源、高溫（0到60攝氏度），極端的濕度、振動、射頻噪聲和其他類似的參數(shù)。通用的應用領(lǐng)域：可編程控制器是用于廣泛的控制應用程序的今天，其中許多是在經(jīng)濟上不可能僅僅幾年前.這是真正的兩個基本原因：1有成本效益，是成本為每I/O點)有明顯的改進與價格下跌的微處理器及相關(guān)部件的能力,和2控制器，以解決復雜的計算和通信任務使得人們有可能使用它在一臺專用電腦以前使用。應用可編程控制器可分為好幾種不同的方式來進行,包括一般及工業(yè)應用的類別。但重要的是要理解這個框架，控制器是目前理解和使用，以便充分發(fā)揮的現(xiàn)狀和未來演變可以審查.它是通過對發(fā)電廠的應用程序控制器中可以看到他們的全部的光。在工業(yè)領(lǐng)域中的應用包括許多在這兩種離散型制造和機械加工等.汽車工業(yè)的應用，可編程控制器的起源,不斷為客戶提供最大的基地的機會的。其他產(chǎn)業(yè)的發(fā)展,諸如食品加工和公用事業(yè),提供當前的發(fā)展機會.有五種通用的應用領(lǐng)域中，可編程控制器的使用。一個典型的安裝將會使用一個或更多的這些綜合控制系統(tǒng)的問題.五個地區(qū)被解釋一般簡要如下。描述:是一種低功耗、AT89C51單片機為核心的微機與高性能CMOS8位字節(jié)的閃光可編程和次方可擦寫只讀存儲器(PEROM)。該裝置采用Atmel制造高密度的非揮發(fā)性記憶體的技術(shù)并兼容行業(yè)標準的pinout通過mcs-51匯編語言指令集。閃光的漢字，允許程序內(nèi)存被編程in—system或由傳統(tǒng)的非易失性存儲器存儲程序員。結(jié)合一個多才多藝的8位單片機上CPU的Flash芯片、Atmel是一個功能強大的單片機AT89C51單片機為核心，提供了一個解決方案highly-flexible許多嵌入式控制應用。功能特點：提供以下標準的AT89C51單片機的特點:次方字節(jié)的閃光,128字節(jié)的內(nèi)存，32I/O線，兩個16位定時器/計數(shù)器,五向量二級中斷體系結(jié)構(gòu)，在全雙工串行端口，樣品的振蕩器和時鐘電路。此外,AT89C51與靜態(tài)邏輯設計和操作減少到零頻率支持兩種軟件可節(jié)電模式。停止CPU空閑模式的同時讓那只公羊來、定時器/計數(shù)器、串行端口和中斷系統(tǒng)繼續(xù)運行。Power—down節(jié)省RAM模式的內(nèi)容但凍結(jié)該振蕩器取消另外的芯片功能直到下一個硬件復位.銷描述VCC：電壓。地上：地面。端口0：端口0是一個8位高電平雙向I/O端口。作為一個輸出端口，每個插腳陷八TTL的投入.當1是寫給端口0銷,highimpedance大頭針可作為輸入。端口0也可以被組態(tài)的多路復用loworder地址/數(shù)據(jù)總線訪問期間的外部程序和數(shù)據(jù)的記憶。在這種模式下并有內(nèi)部pullups。端口0,也帶走了Flash編程代碼字節(jié)，并輸出期間在programverification代碼字節(jié)。在programverification外部pullups被要