本科毕业生外文文献翻译.docx

本科毕业生外文文献翻译.docx

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本科毕业生外文文献翻译

本科毕业生外文文献翻译

学生姓名:

史衍彬

指导教师:

荣丽红

所在学院:

信息技术学院

专　　　业:

农业电气化与自动化

中国·大庆

２０１0年4　月

ＳCＭ　proｆｉle

IntrｏｄｕctｉoｎｏfProｇrammabｌecｏntrollｅｒｓ　

Fromasimplｅ　hｅritaｇｅ,theseremａrｋabｌｅ　syｓteｍs　hａvｅeｖolvedto　ｎot　onｌyrｅplaceelｅｃｔromechanicaldevｉces,buｔtosoｌveaneveｒ-increａsingarrａy　ｏｆcontroｌprｏbｌｅmsｉnｂｏth　proceｓs　aｎdnｏｎprocｅｓsinｄusｔｒｉes.Byａｌlｉｎｄｉcatｉons,thesemiｃｒoｐrｏcｅssorｐｏwered　gｉａntｓwｉllcontinuetobreａknewground　inthｅ　aｕtomａtedfacｔoｒyinto　thｅ１990s.

ＨIＳTORY

In　ｔhe　１9６0ｓ，　ｅlectroｍecｈａｎiｃaldeviceswerｅtheorｄerofthｅｄay　assｆａras　ｃontｒol　ｗａｓconcerｎeｄ．　Thｅｓe　deviceｓ,　coｍmonlykｎｏwnasｒelaｙｓ,werebeiｎguseｄby　tｈetｈousanｄstocontrｏlmａｎysequential－tyｐe　manufacturingprocessesａnｄｓtaｎd-aｌoｎgmachines.Manｙｏf　thesereｌayswｅre　inｕseinｔheｔranspｏrｔａtionindｕstry，　more　ｓｐeciｆiｃａｌly，theａuｔｏmotiveinｄusｔry．Tｈesｅrｅｌａｙsusedhｕｎdredｓofwiｒes　aｎd　theirｉｎtｅrcｏnｎectiｏｎs　toeffeｃtａ　cｏntroｌsｏlutｉon.Thｅpｅrforｍａncｅ　ofarelaｙwasbａsiｃａlｌｙreｌiable-ａt　lｅａst　asaｓingledevice.　Bｕtthe　ｃommoｎapplicatioｎsfor　ｒｅlaypanelｓ　caｌlｅdfor3０0ｔo500ｏrmore　rｅｌays,anｄｔhe　ｒｅlｉａｂiｌｉｔyａndｍainｔｅnance　issueｓaｓｓoｃiateｄｗithsuｐporｔingtheｓｅpaｎｅls　ｂecame　a　very　ｇreat　ｃhallenge.Ｃostｂeｃaｍeaｎotｈer　issue，　fｏrin　spitｅoｆthｅｌow　ｃｏstof　ｔherelaｙｉtselｆ,the　ｉnstaｌlｅdcostｏfthepaneｌcoulｄbeｑuitehigh．Ｔｈetotalｃoｓtinｃludiｎｇｐｕrchased　paｒtｓ,　wiｒing，ａndiｎstaｌｌatｉｏｎlabor,couldranｇｅｆｒom$30～$50　ｐｅrrelａy.　Tｏmａkemａｔｔeｒsworse,theconstantlｙ　ｃhａngｉng　needsｏfa　proｃeｓｓ　calｌed　foｒrecuｒringｍodificationsofａｃontｒｏlpaｎeｌ.　Ｗiｔh　relays,　tｈisｗasacostlyprｏspect，　asiｔwas　accomplisｈｅd　byaｍａｊor　rewiriｎg　ｅffortontheｐanel.Ｉnａddｉtionthesechａnges　weresomｅtimｅｓｐｏorｌｙdocumｅnｔed,ｃａusｉnｇ　aｓecｏｎｄ-shift　maｉnｔｅnanceｎｉｇhtmaremoｎthsｌateｒ.Inlightofthiｓ,ｉtwａsnｏtunｃomｍontｏdｉsｃａrdanｅnｔｉre　contrｏl　paｎeｌ　infaｖoroｆanｅｗonewith　theappropriatecomｐｏnentswireｄ　in　amannerｓuｉｔed　fｏｒtheneｗ　pｒocesｓ．Aｄd　tothｉｓ　theunpredｉctable,aｎｄpoｔｅntｉalｌyｈiｇh,coｓtofmａｉｎtａinｉngthesｅsystems　asoｎ　ｈｉgh－volumｅmotoｒvehiｃlｅ　prodｕctｉonlines,　anditbecameclｅartｈat　soｍｅthinｇwas　nｅeｄedtoimproｖeｔheconｔrolpｒocesｓ–tomakeitmoｒerｅliablｅ,eaｓiertｏtrｏubｌeｓｈoot,　aｎd　ｍｏreaｄaptabｌeｔochangingcontroｌneｅds.　

Thaｔｓoｍethｉng,inthelaｔe1960s,wasthefirst　progrａｍmａｂle　contrｏｌleｒ．Ｔhiｓｆｉrst‘revｏluｔｉonary’system　wanｄevｅlopedａs　aspｅcificrｅspｏnsetotｈｅneedsof　tｈe　ｍajorautｏmotivemanufactｕrｅrsinｔheUnｉｔｅｄＳtateｓ.Theｓeeaｒlycｏntｒoｌｌers,　orprograｍmable　logiccontrｏlleｒs（PLC）,rｅｐrｅsentedtｈefiｒｓt　sｙｓteｍsthat１couldｂｅ　usedontｈｅｆacｔoryfｌoｏr,２cｏuｌd　ｈavetｈｅｒe‘ｌｏgic’chａngｅｄｗitｈoutｅxtensiｖerewiｒing　ｏrｃｏmｐoｎentｃhａnges,and3ｗereeasｙtodiaｇnｏｓeand　repａiｒwhｅnｐroblems　ｏccurｒeｄ．

Itｉsｉntereｓting　toobservｅ　theｐroｇrｅssthａtｈaｓbeenｍade　intheｐast15　years　intｈｅprogramｍaｂlecontrollｅrａｒｅa.Ｔhe　ｐiｏneerpｒoducｔｓ　oｆ　theｌate　1960smｕｓt　havebeenｃonｆｕsinｇandfｒighteniｎg　toagrｅatnumberoｆｐeoｐle.For　examｐlｅ，wｈａthａpｐeｎｅdtｏｔｈeｈaｒｄwｉｒed　andelecｔroｍechaｎｉｃalｄevicｅstｈatmaintenａncepｅrsonnelwｅｒeusedto　reｐａｉriｎgｗithｈａｎd　tｏols?

Theywｅrereｐｌａｃｅdwｉtｈ‘computerｓ’　diｓｇuｉseｄaseleｃtroniｃsdesignｅdto　repｌaｃeｒelａys．Evｅn　thepｒograｍmingtools　wｅre　designeｄtｏappｅａr　asrelayequivaleｎtpresenｔatｉｏnｓ．Wｅhavｅｔhe　ｏpporｔuｎｉｔy　ｎoｗto　eｘａmineｔheprｏmｉse，　inretrospect，　thatｔheprogrammabｌecoｎtroｌleｒbrought　toｍanｕfacｔuring.　

Ａllｐｒoｇrａmｍablecontｒollerｓconsisｔof　tｈebａsｉcfunctｉonal　blocｋsshowninＦig．１0．1．　Ｗe’llexamine　eaｃhblocｋｔoｕndｅｒstaｎdtherelationshiｐto　thecoｎtｒoｌsysｔem.Fiｒstwelook　atthe　ceｎter,　as　iｔｉstｈｅheａｒt　（oｒat　ｌeａsｔtｈebraｉn）oｆｔhesyｓｔem．　Itcoｎｓistｓof　ａmiｃroprｏcessoｒ,logiｃmｅmoryfoｒthe　sｔｏrageof　tｈeactualcontrollogｉc，　storageorvariａbｌｅmemoryfoｒusewitｈdata　tｈａｔwiｌlordinariｌychanｇeas　aｆunｃｔion　ｐower　ｆorｔｈeprｏｃessoraｎdmｅmorｙ．NextｃomeｓtheI/Oｂloｃk．Thiｓfuncｔion　takｅｓthecoｎtrｏllｅvelsｉgnａls　foｒtheCPU　ａnｄcｏnvｅrts　themtoｖoｌtage　andcurrentleｖels　suｉtａbleｆorconnectionwiｔhfａctorygradeｓensors　ａｎdactuaｔｏｒs.TｈｅI／Oｔyｐecanraｎgｅfｒomdigitａl（discｒete　or　oｎ　／ｏff），ａｎaｌog（cｏntinuousｌｙ　vａriablｅ）,ｏravａrietyｏfspecｉalpuｒpｏsｅ‘smart’I／Owhiｃｈarｅdedicatedtoa　cerｔａiｎ　appｌicationtａｓｋ.Ｔｈeprｏgrammｅriｓshｏwnhere,　but　itｉｓ　normallyｕsed　ｏnlyto　inｉtｉaｌly　coｎfｉgurｅaｎdｐrogrａm　ａsystemandｉｓ　nｏtrｅquireｄforｔhｅsysteｍto　operate.Itis　alｓｏuｓed　iｎtｒoublｅshｏｏｔingａ　sｙstｅm,ａnd　cａnprｏvetｏ　ｂeavａｌuabletoolｉnｐinpｏｉnｔingｔheｅxact　causeofａprobｌem．Thｅfielddeviceｓｓｈｏwn　ｈerｅrｅpresenttｈｅvarioｕｓ　seｎsoｒs　andaｃｔuatｏｒsｃonnｅctedtｏthe　I／O.　Thｅsｅaｒｅｔhe　arms,　ｌegs,eyｅs,anｄｅａrs　ofthｅsｙstｅm,iｎcｌｕdinｇpｕｓhbutｔons,　liｍitsｗitcｈｅｓ，　ｐroximityｓｗiｔches，ｐhotosｅnｓｏｒs，therｍoｃouples,RＴＤS，　posｉtiｏnsｅｎsingｄeviｃeｓ，anｄｂarcodｅ　rｅａｄerａs　inｐut;aｎdｐiｌotｌiｇｈｔs,ｄisplaydeｖｉces,ｍｏtoｒ　ｓtarｔerｓ,DC　anｄ　ACｄrives,solenｏids,　andprinｔｅrｓａsoｕtpｕts.

Nosiｎgleａttｅmpｔcoulｄ　coｖeritsraｐidlｙchaｎｇingｓｃｏpｅ，ｂutthree　basｉｃcharacteｒistics　canbe　examｉnｅｄtｏgive　ｃlassｉｆyanindustｒiａlｃontrｏlｄeviceas　aｐｒｏgrａｍmaｂｌｅ　cｏntrｏller．

（1）Ｉtsbａｓiciｎterｎａloｐｅratｉoniｓ　ｔosolｖe　logｉcfromtｈｅ　beginｎｉnｇofmemorytosoｍe　spｅｃｉｆiedｐｏｉnｔ，suchasendof　memｏrｙorｅndｏｆprogｒam.Oｎcetｈｅｅｎdiｓreached，theｏperationbｅgｉｎsagaiｎ　ａttheｂeginningｏfmｅmｏry.Tｈis　sｃannｉng　prｏｃess　ｃｏntinｕesfrｏｍthｅtiｍｅpoweｒｉssuppｌiedto　ｔhetimeitit　removｅｄ.　

（２）Tｈe　pｒogrａmminｇｌogicis　afoｒmｏｆarelaｙｌaｄdeｒdｉagｒaｍ.Normａllyoｐeｎ,ｎoｒmａｌly　closed　coｎｔacts,and　relay　cｏｉlｓareｕｓed　withiｎaformat　ｕtilizｉngaleｆtandａriｇhｔ　verｔical　ｒaｉl．Pｏwerflｏｗ（symboliｃpｏsitivｅ　eｌectronｆｌow）　isuｓed　todｅtｅrmiｎe　whichcoilｏr　outｐｕtsarｅｅｎeｒgiｚｅdordeｅnｅrgized.

（3）Themaｃhinｅis　dｅsｉgnｅdｆorthｅ　ｉndustrialeｎvｉｒonmenｔfｒｏmｉtsbasiｃconceｐt;ｔhisprｏtectiｏnisnoｔ　addedata　laｔerｄate.Ｔｈeindustｒｉal　ｅnｖirｏnmenｔincluｄes　ｕnｒeliable　ACｐoweｒ,ｈiｇhteｍｐeratures（0to60　degreｅCelsius），extrｅｍesｏｆ　ｈｕmiｄity，　vibrations,RFnoise，andotｈersiｍｉｌarpａrａmｅtｅrs.

Ｇｅneralappｌｉcａtionareaｓ　

Thｅ　prｏgramｍablｅ　contｒｏlleriｓused　inaｗideｖariｅtyoｆcontrｏｌ　applicatiｏnstｏday,ｍanyofwhicｈ　ｗere　noteｃonomicallypossｉｂle　juｓta　fewyeａｒsaｇo.Tｈisｉs　ｔrueforｔwoｇeｎerａlreaｓons：

　１there　costeffｅctiveｎｅss（ｔhaｔ　iｓ,　ｔｈecoｓt　perI/Opoｉｎt）ｈasｉｍpｒoｖｅｄdramaticaｌlｙｗith　theｆａｌlinｇpｒicesofｍｉcroprocessorｓaｎｄrelatｅｄｃoｍｐｏnenｔs,and2tｈeabｉlitｙoftｈe　conｔroller　tosolve　comｐｌｅｘcoｍｐutatiｏｎanｄcoｍmuniｃaｔｉonｔaskshasmadeｉt　possｉｂｌe　tｏ　use　it　wheｒe　adedicateｄcoｍｐuter　ｗas　ｐrｅviouｓｌyuｓed．

Applicaｔionsforprograｍmablｅ　coｎtroｌｌｅrscanbecategoｒiｚedin　ａnｕmｂｅr　ofdｉffｅrｅntｗａyｓ,iｎclｕding　genｅraｌand　iｎdusｔｒialaｐｐｌiｃatioｎcaｔegｏries．Butitisimportant　tounｄerｓtand　tｈefraｍeworｋin　which　controllｅｒs　areｐresentｌyunderstoodandusｅdsoｔhａｔｔhefulｌscopｅofpresent　and　futuｒe　evoｌｕｔioncanbe　exａmined.It　isｔｈrｏughthｅpoweｒofａｐpliｃaｔioｎstｈatconｔｒｏｌlerｓ　cａn　beseｅnintheirfuｌl　ｌiｇht.Industriａlapplｉcaｔionsiｎcludemany　iｎbothdｉscreｔe　ｍａnufaｃturｉngandpｒocess　induｓｔries．Auｔomotive　iｎdustrｙapplｉcａｔｉons,thegenesｉｓ　oftｈｅ　proｇｒamｍaｂｌeｃontrｏｌleｒ,　coｎtinｕeto　provide　ｔhｅlargｅstｂaｓeof　ｏpportunity.　Oｔherinｄusｔriｅs,suchaｓｆｏodｐｒocessinｇ　anduｔiliｔies,ｐrovidｅｃurrent　ｄevelopmｅntｏpｐorｔunitiｅｓ．　

Tｈere　are　fiｖegeｎerａlａｐpｌicationaｒeasｉn　wｈichproｇｒammablｅcontｒｏｌlersarｅｕsｅd.Atypicalinsｔallａtiｏnｗilluse　oneoｒmｏｒeoｆ　thｅsｅintegrated　tｏthe　conｔrolsysｔemｐrｏblｅm．Ｔｈeｆｉve　ｇｅneraｌarｅａs　ａreexplained　ｂrｉｅflybelow．　

Ｄescｒiｐtｉon

Thｅ　AT89C51is　aｌｏw-ｐoweｒ，high－pｅrfoｒｍａnce　CMOＳ8－ｂｉtmicｒocoｍputｅｒwith４Kｂｙteｓof　Flａshproｇrammaｂlｅ　aｎｄerasablereａｄ　ｏnlｙｍeｍory（PEROＭ）.Theｄｅviceiｓ　manｕfactｕrｅｄusｉnｇAｔｍel’s　hiｇh-ｄensitｙnoｎvoｌａtilｅｍeｍorｙ　technｏlｏｇｙandiscoｍｐatｉble　wｉtｈ　ｔｈeiｎｄuｓtry-stanｄard　MCS-51　instｒｕｃtｉonseｔ　andpｉnouｔ.Theon-chiｐFｌashalｌowsｔｈeprogrammemorｙtobe　reｐrogrａｍｍedin-sｙsｔeｍ　orbyaconventiｏnaｌnｏnvoｌatile　mｅmｏryprogrammer.Ｂycoｍbｉninga　ｖerｓatile8-bitCPＵwith　Flａsh　on　ａmonolｉｔhiccｈｉｐ,the　AｔｍelAＴ89Ｃ51iｓa　poweｒfulｍｉcrocomputeｒ　ｗhｉcｈproviｄｅｓａhiｇhｌｙ-fleｘiｂｌeandcｏｓｔ-ｅｆfｅctivesｏｌutiontomanｙｅmｂeddeｄ　contrｏlapplicatｉons．

Fｕnctionchaｒaｃteristic

Tｈe　AT８9C５１providｅｓthｅfｏlloｗiｎgstandardｆeａｔurｅs：

4ＫbytesｏfＦｌasｈ，１2８　byｔes　ｏfＲＡM,　32I/O　lineｓ,two16-bittimｅｒ/coｕnters,afiｖevecｔｏｒ　two-levelinterruptａｒcｈitecｔure，　afull　duｐｌexseｒｉaｌ　ｐｏrt,　on-ｃｈiposcillator　anｄcｌockcｉｒcuｉtry．Inadditiｏｎ,the　AT89C５１isdｅsigned　ｗｉthsｔaｔiｃloｇiｃ　foｒ　opeｒationｄoｗntozerofreｑｕencyａnｄsupports　two　ｓofｔwａreselecｔablepｏｗer　sａvingmodes.　The　IdｌeModestｏｐs　theCＰＵwhile　ａlｌowiｎｇｔhｅRＡＭ,ｔｉmｅr/cｏunterｓ,seriaｌportaｎdinteｒｒupｔ　systemtoｃontinueｆunｃｔioniｎg．ThePowｅr-ｄown　MoｄesａｖeｓｔheRAMcontenｔsbutfrｅezeｓtｈeoscｉｌｌatｏrdｉｓablｉｎg　alloｔherｃｈiｐfunctｉonsuｎtilthenexthardwaｒereseｔ．

Pｉｎ　Desｃriｐｔｉｏn

VCC:

Suppｌy　vｏlｔagｅ.　

GNＤ：

Ｇrounｄ.　

Poｒt0:

Porｔ　0ｉsａn8-bｉｔopen－dｒａin　bi-dｉreｃtionaｌI/Oｐort.　Ａｓａnoutputｐorｔ,eaｃhpｉn　caｎsｉnｋeiｇｈtTTLｉnpuｔｓ．When　1sａrｅwrittenｔｏｐoｒt０pinｓ,the　pins　cａnbｅ　useｄａshighｉmpｅｄａncｅinpｕtｓ．Poｒt0mａy　ａｌsobeｃonfigureｄtｏbe　theｍuｌｔｉpｌexｅd　lｏｗorderaｄdresｓ/dａtａ　buｓ　dｕrｉｎg　ａcｃｅsses　toexternalｐrogram　andｄata　memory．IntｈismｏｄeＰ0　ｈａs　ｉnterｎalpｕllｕps．Port　0alｓoreceivｅs　thｅ　cｏｄeｂyｔesｄｕrinｇ　Ｆlash　ｐｒoｇｒamming，andｏｕtputsｔhｅ　coｄebyteｓduｒｉｎｇpｒoｇramｖerificatioｎ.　Exｔerｎａｌｐullupsarereｑｕｉrｅd　during　progrａｍvｅｒificａtiｏn.　

Ｐorｔ1

Ｐorｔ１ｉｓａn8-biｔbｉ-direcｔionaｌI／O　pｏrtwiｔh　inｔerｎａlｐullupｓ.ＴheＰort1ouｔput　buffｅrｓcaｎsiｎk/sｏｕｒcefｏurTTＬiｎpｕts．When1sareｗriｔteｎto　Port１ｐiｎstheyarepulled　highby　theinternalpｕllups　andｃanｂｅusedaｓｉnputs．Ａsinpｕts,Port1ｐinｓｔhａtａｒeexternallybeingpｕｌｌeｄｌowwillsｏurcecｕrｒent　（IIL）　becaｕｓeoｆtheiｎtｅrnａlpuｌlupｓ.Port　1　alsorｅceｉvｅstｈeloｗ