中英文翻譯--rs-232通信協(xié)議及接口標(biāo)準(zhǔn)【適用于畢業(yè)論文外文翻譯】

英文文獻(xiàn)RS232COMMUNICATIONSAGREEMENTSANDSTANDARDINTERFACESRS232COUTLINEDSERIALCOMMUNICATIONSINTERFACESTANDARDSTHROUGHTHEUSEANDDEVELOPMENT,THEREAREALREADYSEVERALBUTINRS232STANDARDSAREIMPROVED,ANDFORMEDTHEBASISRS232CUSEIAELECTRONICINDUSTRYASSOCIATION,TOGETHERWITHTHEBELLCOMPANIESIN1969ANNOUNCEDTHEDEVELOPMENTOFCOMMUNICATIONAGREEMENTIT020000B/SSUITABLEFORDATATRANSMISSIONRATEINTHECONTEXTOFCOMMUNICATIONSTHISSTANDARDFORSERIALCOMMUNICATIONSINTERFACEONTHEISSUES,SUCHASSIGNALLINEFUNCTIONS,ELECTRICALCHARACTERISTICSWERECLEARLYDEFINEDSINCEPASSAGEOFTHEPRODUCTIONEQUIPMENTMANUFACTURERSARECOMPATIBLEWITHRS232CSTANDARDCOMMUNICATIONSEQUIPMENT,ANDTHEREFOREITASASTANDARD,ISNOWWIDELYUSEDINCOMPUTERCOMMUNICATIONSINTERFACEINDISCUSSINGTHECONTENTOFRS232CINTERFACESTANDARDSBEFOREONTWOPOINTSFIRST,LONGRANGECOMMUNICATIONSLINKINITIALLYRS232CSTANDARDDATATERMINALEQUIPMENTDTEDATATERMINALEQUIPMENTANDDATACOMMUNICATIONSEQUIPMENTDCEDATACOMMUNICATIONEQUIPMENTDEVELOPEDTHEREFORETHESTANDARDSANDDOESNOTCONSIDERTHEAPPLICATIONOFCOMPUTERSYSTEMSBUTNOWITWASWIDELYBORROWEDFORCOMPUTERSMOREACCURATELY,ISACOMPUTERINTERFACEBETWEENTHESCALESOFENGINEEREDWITHTERMINALORCONNECTINGSTANDARDCLEARLY,SOMEOFTHEREQUIREMENTSANDSTANDARDSANDCOMPUTERSYSTEMSISINCONSISTENT,ANDEVENCONTRADICTORYWITHTHISBACKGROUNDKNOWLEDGE,WERS232CCOMPUTERINCOMPATIBLEWITHTHESTANDARDSOFLOCALNOTDIFFICULTTOUNDERSTANDSECONDLY,RS232CCRITERIAMENTIONED“SENDING“AND“RECEIVING“ARESTANDINGDTEPOSITION,RATHERTHANSTANDINGATTHEPOSITIONOFDCETOTHEDEFINITIONINCOMPUTERSYSTEMS,OFTENBETWEENTHECPUANDI/OEQUIPMENTTRANSMISSIONOFINFORMATIONBOTHDTEANDTHEREFOREBOTHSENDINGANDRECEIVINGRS232CINTERFACESTANDARDSRS232CSTANDARDSAGREEMENTISTHEFULLNAMESEIARS232STANDARDS,INCLUDINGEIAELECTRONICINDUSTRYASSOCIATION,SPEAKINGONBEHALFOFTHEUSELECTRONICSINDUSTRYASSOCIATION,RSRECOMMEDEDSTANDARD,SPEAKINGONBEHALFOFRECOMMENDEDSTANDARDS,232ISTHEIDENTIFICATIONNUMBER,THELATESTREVISIONCREPRESENTATIVERS2321969,INTHEMEANTIME,RS232B,RS232AITPROVIDESCONNECTINGCABLESANDMECHANICAL,ELECTRICALCHARACTERISTICS,FUNCTIONSANDSIGNALTRANSMISSIONPROCESSTHEREAREALSOCOMMONPHYSICALSTANDARDEIARS232C,EIARS422A,EIARS423A,EIARS485HEREONLYONEIARS232CSHORTFOR232,RS232FOREXAMPLE,THEIBMPCMACHINESCURRENTLYINTHECOM1,COM2INTERFACEISRS232CINTERFACES1ELECTRICALCHARACTERISTICSEIARS232CFORELECTRICALCHARACTERISTICS,FUNCTIONALLOGICOFPEACEFULVARIOUSSIGNALLINESAREPROVIDEDINTHETXDANDRXDLOGIC1MARK3V15V,LOGIC0SPACE315VINTHERTS,CTS,DSR,DTR,ANDDCDCONTROLLINESIGNALEFFECTIVECONNECTED,ONSTATEISVOLTAGE3V15V,SIGNALVOIDBREAKAPART,THEOFFSTATE,ANEGATIVEVOLTAGE3V15VTHEABOVEPROVISIONSONTHECRITERIAOFLOGICCALLRS323CPINGDEFINITIONTHEDATAINFORMATIONCODELOGIC“1“ELECTRICITYPINGBELOW3V,LOGIC“0“AIRTHANTHECALLPING3VFORCONTROLSIGNALSCONNECTEDSTATE5B6THATTHEEFFECTIVESIGNALTHAN3VCALLPING,BREAKAPARTSTATEOFFTHATSIGNALSINVALIDCALLPINGBELOW3V,WHENPINGISTHEABSOLUTEPOWERTRANSMISSIONTHAN3V,THECIRCUITCANEFFECTIVELYCHECKOUTSOMEWHEREBETWEENTHEVOLTAGEMEANINGLESS33VBELOWORABOVE15V15VTHEVOLTAGEBELIEVEMEANINGLESS,ANDTHEREFORE,THEACTUALWORKSHOULDBEGUARANTEEDINTHEELECTRICPING315VBETWEEN2THEMECHANICALPROPERTIESCONNECTORSASRS232CNOTDEFINEDCONNECTORSPHYSICALCHARACTERISTICS,ANDTHEREFORETHEREDB25,DB15ANDDB9VARIOUSTYPESOFCONNECTORS,LEADSFEETDEFINITIONSVARYTHETWOCONNECTORSWEREINTRODUCED（1）DB25CONNECTORSPCANDXTMACHINESUSEDDB25TYPECONNECTORSDB25CONNECTORSDEFINITIONOFAROOTSIGNALLINE25,DIVIDEDINTOFOURGROUPSASYNCHRONOUSCOMMUNICATIONSNINEVOLTAGESIGNALSINCLUDINGSIGNALTOSG2,3,4,5,6,7,8,20,22CENTRAL20MACURRENTSIGNAL912,13,14,15,16,17,19,23,24AIR69,10,11,18,21,25PROTECTORATEPE1ASEQUIPMENTGROUNDEDENDSONEFOOTATTENTION20MACURRENTSIGNALONLYPARTPC/XTIBMPCANDIBMMACHINESTOPROVIDETOATPLANEANDBEYOND,ISNOTSUPPORTED（2）DB9CONNECTORSINATPLANEANDBEYOND,DONOTSUPPORT20MACURRENTLINKINTERFACES,THEUSEOFDB9CONNECTORS,ASACARDORMAINBOARD,WITHMULTIFUNCTIONALI/OCOM1ANDCOM2TWOSERIALINTERFACELINKTHECONNECTORSITPROVIDESASYNCHRONOUSCOMMUNICATIONSNINESIGNALSDB25TYPECONNECTORSLEADSFEETDISTRIBUTIONANDTHETYPELEADSFEETDB25SIGNALCOMPLETELYDIFFERENTTHEREFORE,IFTHEALLOCATIONTOTHEDCEDB25TYPECONNECTORSCONNECTINGEQUIPMENTTOUSESPECIALIZEDCABLESLINESCABLELENGTHINCOMMUNICATIONSRATEBELOW20KB/S,RS232CDIRECTPHYSICALDISTANCEOF15MFROMTHELARGEST50FEETLARGESTDIRECTTRANSMISSIONDISTANCENOTERS232CSTANDARDSREQUIRETHATIFTHEUSEOFMODEM,CODEDISTORTIONSINLESSTHAN4OFTHEMAXIMUMTRANSMISSIONDISTANCEBETWEENDTEANDDCEFOR15M50FTITISTHELARGESTDISTANCEINYARDSPERDISTORTIONSLESSTHAN4GIVENTHEPREMISETOENSURETHATCODESFORLESSTHAN4OFTHEDISTORTIONS,INTERFACESTANDARDSINTHEELECTRICALPROPERTIESTHAT,THEDRIVESHOULDBELESSTHAN2500PFLOADCAPACITANCE3THEINTERFACESIGNALSRS232CFIGURE22RS232LEADSFEETFIGURERS232CCONVENTIONALSTANDARDSINTERFACE25LINES,FOURLINESOFDATA,11LINEOFCONTROL,3REGULARLINES,7STANDBYANDMISSINGLINES,COMMONLYUSEDONLYNINEROOTS,ANDTHEYARELIAISONCONTROLSIGNALLINESDATAREADYDEVICESDATASETREADYDSREFFECTIVEONSTATETHATCOULDBEUSEDMODEMINTHESTATEDATATERMINALREADYDATATERMINALREADYDTREFFECTIVEONSTATETHATDATATERMINALSCANBEUSEDSOMETIMESEVENTOTHEPOWEROFTHESETWOSIGNALS,ONEONTHECALLIMMEDIATELYEFFECTIVETWOSTATESIGNALSEFFECTIVEEQUIPMENT,BUTINDICATEDTHATTHEEQUIPMENTITSELFCOULDBEUSED,DOESNOTINDICATEACOMMUNICATIONLINKCANINITIATECOMMUNICATIONCANBEGINBYFOLLOWINGCOMMUNICATIONTOTHECONTROLSIGNALSREQUESTSENTREQUESTTOSENDRTSUSEDTOEXPRESSDTEDCEREQUESTSENTDATATOBESENTWHENDATATERMINALS,SOTHATASIGNALONSTATE,AREQUESTSENTTOMODEMITISUSEDTOCONTROLACCESSTOSTATEMODEMALLOWTRANSMISSIONCLEARTOSENDCTSUSEDTOEXPRESSDCEDTEMADEREADYTORECEIVETHEDATASIGNALISSENTTOREQUESTTHERESPONSERTSSIGNALWHENMODEMISREADYTORECEIVEDATATRANSMITTEDFROMTERMINAL,ANDMOVETO,SOTHATTHEEFFECTIVESIGNALTOINFORMTERMINALSBEGINSENDINGDATAALONGTHELINESTXDSENDINGDATATHISREQUESTRECEIVEDRTS/CTSCONTACTSIGNALISSENTTO3,6004,000MODEMSYSTEMBETWEENTHECUTOVERWAYSANDMEANSTORECEIVEINFULLTWOWAYWORKSYSTEMFORTRANSMISSIONANDRECEPTIONOFWAYBETWEENTHECUTOVERINFULLTWOWAYWORKSYSTEMFORTHEALLOCATIONOFTWOWAYROUTES,SOTHEREISNONEEDRTS/CTSCONTACTSIGNALSTOCHANGEHIGHRECEIVELINESIGNALSDEPARTURECLEARANCEBEIJINGLINEDETECTIONRLSDUSEDTOEXPRESSDCEHASCONNECTEDCOMMUNICATIONSLINKSTOINFORMDTEREADYTORECEIVEDATAWHENLOCALMODEMRECEIVEDBYTHEOTHERSIDEOFCOMMUNICATIONLINKSDISTANTMODEMSENTTOTHECARRIERSIGNAL,THESIGNALRLSDEFFECTIVE,INFORMEDTERMINALREADYTORECEIVE,ANDWILLRECEIVEFROMMODEMDEMODULATESIGNALSFROMTHECARRIERINTOTHEDIGITALTRAFFICDATA,ALONGRXDLINETORECEIVEDATATERMINALSTHELINEISALSOKNOWNASDATACARRIERDEPARTURECLEARANCEDATACARRIERDETECTIONDCDLINERINGINGINSTRUCTIONSRINGINGRIWHENMODEMSENTTHESWITCHBOARDRECEIVEDRINGINGCALLSIGN,SIGNALTOTHEEFFECTIVEONSTATE,INFORMEDTERMINALSHAVEBEENSHOUTINGSENDANDRECEIVEDATALINESSENDDATATRANSMITTEDDATATXDTHROUGHTXDSERIALDATATERMINALSWILLBESENTTOMODEM,DTEDCE。RECEIVINGDATABEIJINGDATARXDTHROUGHRXDLINETERMINALSRECEIVEDATAFROMMODEMMADETOTHESERIAL，DCEDTE。EARTHTHEREARETWOLINESSG,PGSIGNALTOTHESIGNALLINEANDTHEPROTECTION,WITHOUTDIRECTIONTHECONTROLSIGNALLINEWHENEFFECTIVE,ANDWHENTHEORDEREXPRESSEDINTERFACESIGNALTRANSMISSIONPROCESSFOREXAMPLE,ONLYWHENDSRANDDTRAREINTHEEFFECTIVEONSTATUS,CANBETRANSMITTEDBETWEENTHEDTEANDDCEOPERATIONIFTHEDTETOSENDDATA,THEADVANCEWILLBUYINTOEFFECTIVEDTRLINEONSTATUS,SUCHASCTSLINERECEIVEDEFFECTIVEONOFTHEANSWER,CANSENDSERIALDATAATTXDLINETHISSEQUENCEOFTHEPROVISIONSOFHALFOFTHETWOWAYWORKLINESOFCOMMUNICATIONPARTICULARLYUSEFULBECAUSEDUPLEXCOMMUNICATIONCANBEDETERMINEDBYTHEDCETORECEIVEDIRECTIONSTOTHEDIRECTIONOFTHISLINECANBEGINSENDINGRS232通信協(xié)議及接口標(biāo)準(zhǔn)RS232C概述串行通信接口標(biāo)準(zhǔn)經(jīng)過(guò)使用和發(fā)展，目前已經(jīng)有幾種。但都是在RS232標(biāo)準(zhǔn)的基礎(chǔ)上經(jīng)過(guò)改進(jìn)而形成的。RS232C是美國(guó)EIA電子工業(yè)聯(lián)合會(huì)與BELL等公司一起開(kāi)發(fā)的1969年公布的通信協(xié)議。它適合于數(shù)據(jù)傳輸速率在020000B/S范圍內(nèi)的通信。這個(gè)標(biāo)準(zhǔn)對(duì)串行通信接口的有關(guān)問(wèn)題，如信號(hào)線功能、電器特性都作了明確規(guī)定。由于通行設(shè)備廠商都生產(chǎn)與RS232C制式兼容的通信設(shè)備，因此，它作為一種標(biāo)準(zhǔn)，目前已在微機(jī)通信接口中廣泛采用。在討論RS232C接口標(biāo)準(zhǔn)的內(nèi)容之前，先說(shuō)明兩點(diǎn)首先，RS232C標(biāo)準(zhǔn)最初是遠(yuǎn)程通信連接數(shù)據(jù)終端設(shè)備DTEDATATERMINALEQUIPMENT與數(shù)據(jù)通信設(shè)備DCE（DATACOMMUNICATIONEQUIPMENT）而制定的。因此這個(gè)標(biāo)準(zhǔn)的制定，并未考慮計(jì)算機(jī)系統(tǒng)的應(yīng)用要求。但目前它又廣泛地被借來(lái)用于計(jì)算機(jī)（更準(zhǔn)確的說(shuō)，是計(jì)算機(jī)接口）與終端或外設(shè)之間的近端連接標(biāo)準(zhǔn)。顯然，這個(gè)標(biāo)準(zhǔn)的有些規(guī)定及和計(jì)算機(jī)系統(tǒng)是不一致的，甚至是相矛盾的。有了對(duì)這種背景的了解，我們對(duì)RS232C標(biāo)準(zhǔn)與計(jì)算機(jī)不兼容的地方就不難理解了。其次，RS232C標(biāo)準(zhǔn)中所提到的“發(fā)送”和“接收”，都是站在DTE立場(chǎng)上，而不是站在DCE的立場(chǎng)來(lái)定義的。由于在計(jì)算機(jī)系統(tǒng)中，往往是CPU和I/O設(shè)備之間傳送信息，兩者都是DTE，因此雙方都能發(fā)送和接收。RS232C接口標(biāo)準(zhǔn)RS232C標(biāo)準(zhǔn)協(xié)議的全稱是EIARS232標(biāo)準(zhǔn),其中EIAELECTRONICINDUSTRYASSOCIATION代表美國(guó)電子工業(yè)協(xié)會(huì)，RS（RECOMMEDEDSTANDARD）代表推薦標(biāo)準(zhǔn)，232是標(biāo)識(shí)號(hào)，C代表RS232的最新一次修改（1969），在這之前，有RS232B、RS232A。它規(guī)定連接電纜和機(jī)械、電氣特性、信號(hào)功能及傳送過(guò)程。常用物理標(biāo)準(zhǔn)還有有EIARS232C、EIARS422A、EIARS423A、EIARS485。這里只介紹EIARS232C（簡(jiǎn)稱232，RS232）。例如，目前在IBMPC機(jī)上的COM1、COM2接口，就是RS232C接口。1電氣特性EIARS232C對(duì)電器特性、邏輯電平和各種信號(hào)線功能都作了規(guī)定。在TXD和RXD上邏輯1MARK3V15V，邏輯0SPACE315V在RTS、CTS、DSR、DTR和DCD等控制線上信號(hào)有效（接通，ON狀態(tài)，正電壓）3V15V，信號(hào)無(wú)效（斷開(kāi)，OFF狀態(tài)，負(fù)電壓）3V15V以上規(guī)定說(shuō)明了RS323C標(biāo)準(zhǔn)對(duì)邏輯電平的定義。對(duì)于數(shù)據(jù)（信息碼）邏輯“1”（傳號(hào)）的電平低于3V，邏輯“0”（空號(hào)）的電平高于3V；對(duì)于控制信號(hào)；接通狀態(tài)（ON）即信號(hào)有效的電平高于3V，斷開(kāi)狀態(tài)OFF即信號(hào)無(wú)效的電平低于3V，也就是當(dāng)傳輸電平的絕對(duì)值大于3V時(shí)，電路可以有效地檢查出來(lái)，介于33V之間的電壓無(wú)意義，低于15V或高于15V的電壓也認(rèn)為無(wú)意義，因此，實(shí)際工作時(shí)，應(yīng)保證電平在315V之間。（2）連接器的機(jī)械特性由于RS232C并未定義連接器的物理特性，因此，出現(xiàn)了DB25、DB15和DB9各種類型的連接器，其引腳的定義也各不相同。下面分別介紹兩種連接器。1）DB25連接器PC和XT機(jī)采用DB25型連接器。DB25連接器定義了25根信號(hào)線，分為4組異步通信的9個(gè)電壓信號(hào)（含信號(hào)地SG）2，3，4，5，6，7，8，20，2220MA電流環(huán)信號(hào)9個(gè)（12，13，14，15，16，17，19,23，24）空6個(gè)（9，10，11，18，21，25）保護(hù)地（PE）1個(gè)，作為設(shè)備接地端（1腳）注意，20MA電流環(huán)信號(hào)僅IBMPC和IBMPC/XT機(jī)提供，至AT機(jī)及以后，已不支持。2）DB9連接器在AT機(jī)及以后，不支持20MA電流環(huán)接口，使用DB9連接器，作為提供多功能I/O卡或主板上COM1和COM2兩個(gè)串行接口的連接器。它只提供異步通信的9個(gè)信號(hào)。DB25型連接器的引腳分配與DB25型引腳信號(hào)完全不同。因此，若與配接DB25型連接器的DCE設(shè)備連接，必須使用專門(mén)的電纜線。電纜長(zhǎng)度在通信速率低于20KB/S時(shí)，RS232C所直接連接的最大物理距離為15M（50英尺）。最大直接傳輸距離說(shuō)明RS232C標(biāo)準(zhǔn)規(guī)定，若不使用MODEM，在碼元畸變小于4的情況下，DTE和DCE之間最大傳輸距離為15M（50英尺）?？梢?jiàn)這個(gè)最大的距離是在碼元畸變小于4的前提下給出的。為了保證碼元畸變小于4的要求，接口標(biāo)準(zhǔn)在電氣特性中規(guī)定，驅(qū)動(dòng)器的負(fù)載電容應(yīng)小于2500PF。（3）RS232C的接口信號(hào)圖22RS232引腳圖RS232C規(guī)標(biāo)準(zhǔn)接口有25條線，4條數(shù)據(jù)線、11條控制線、3條定時(shí)線、7條備用和未定義線，常用的只有9根，它們是聯(lián)絡(luò)控制信號(hào)線數(shù)據(jù)裝置準(zhǔn)備好（DATASETREADYDSR）有效時(shí)（ON）狀態(tài)，表明MODEM處于可以使