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】.doc

英文文獻(xiàn) RS-232 communications agreements and standard interfaces RS-232C outlined Serial communications interface standards through the use and development, there are already several. But in RS-232 standards are improved, and formed the basis. RS-232C U.S. EIA (Electronic Industry Association), together with the Bell companies in 1969 announced the development of communication agreement. It 020000b/s suitable for data transmission rate in the context of communications. This standard for serial communications interface on the issues, such as signal line functions, electrical characteristics were clearly defined. Since passage of the production equipment manufacturers are compatible with RS-232C standard communications equipment, and therefore it as a standard, is now widely used in computer communications interface. In discussing the content of RS-232C interface standards before on two points : First, long-range communications link initially RS-232C standard data terminal equipment DTE (Data Terminal Equipment) and data communications equipment DCE (Data Communication Equipment) developed. Therefore the standards and does not consider the application of computer systems. But now it was widely borrowed for computers (more accurately, is a computer interface) between the scales of engineered with terminal or connecting standard. Clearly, some of the requirements and standards and computer systems is inconsistent, and even contradictory. With this background knowledge, we RS-232C computer incompatible with the standards of local not difficult to understand. Secondly, RS-232C criteria mentioned sending and receiving are standing DTE position, rather than standing at the position of DCE to the definition. In computer systems, often between the CPU and I/O Equipment transmission of information both DTE and therefore both sending and receiving. RS-232C interface standards RS-232C standards (agreement) is the full names EIA-RS-232 standards, including EIA (Electronic Industry Association), speaking on behalf of the U.S. Electronics Industry Association, Rs ( Recommeded standard), speaking on behalf of recommended standards, 232 is the identification number, the latest revision C representative RS232 (1969), in the meantime, RS232B, RS232A. . It provides connecting cables and mechanical, electrical characteristics, functions and signal transmission process. There are also common physical standard EIARS-232-C, EIARS-422-A, EIARS-423A, EIARS-485. Here only on EIARS-232-C (short for 232,RS232). For example, the IBM PC machines currently in the COM1, COM2 interface is RS-232C interfaces. (1) electrical characteristics EIA-RS-232C for electrical characteristics, functional logic of peaceful various signal lines are provided. In the TXD and RXD : Logic 1 (Mark) =-3V-15V, logic 0 (space) =+3+15V In the RTS, CTS, DSR,DTR, and DCD control line : Signal effective (connected, on state is voltage) =+3V+15V, signal void (break apart, the off state, a negative voltage) =-3V-15V The above provisions on the criteria of logic call RS-323C Ping definition. The data (information code) : logic 1 (-) electricity ping below -3V, logic 0 (air) than the call ping +3V; for control signals; connected state (5B6) that the effective signal than +3V call ping, break apart state (off) that signals invalid call ping below -3V, When Ping is the absolute power transmission than 3V, the circuit can effectively check out somewhere between the voltage meaningless -3+3V below or above +15V -15V the voltage believe meaningless, and therefore, the actual work should be guaranteed in the electric ping + (315) V between. (2) the mechanical properties connectors As RS-232C not defined connectors physical characteristics, and therefore there DB-25, DB-15 and DB-9 various types of connectors, Leads feet definitions vary. The two connectors were introduced. （1） DB-25 connectors PC and XT machines used DB-25 type connectors. DB-25 connectors definition of a root signal line 25, divided into four groups : asynchronous communications nine voltage signals (including signal to SG) 2,3,4,5,6,7,8,20,22 Central 20mA current signal 9 (12,13,14,15,16,17,19,23,24) Air 6 (9,10,11,18,21,25) Protectorate (PE) 1 as equipment grounded ends (one foot) Attention 20mA current signal only part PC/XT IBM PC and IBM machines to provide to at plane and beyond, is not supported. （2） DB-9 connectors In at plane and beyond, do not support 20mA current link interfaces, the use of DB-9 connectors, as a card or main board, with multifunctional I/O COM1 and COM2 two serial interface Link the connectors. It provides asynchronous communications nine signals. DB-25 type connectors Leads feet distribution and the type Leads feet DB-25 signal completely different. Therefore, if the allocation to the DCE DB-25 type connectors connecting equipment to use specialized cables lines. Cable length : In communications rate below 20kb/s, RS-232C direct physical distance of 15m from the largest (50 feet). Largest direct transmission distance Note : RS-232C standards require that if the use of modem, code distortions in less than 4% of the maximum transmission distance between DTE and DCE for 15m (50 ft). It is the largest distance in yards per distortions less than 4% given the premise. To ensure that codes for less than 4% of the distortions, interface standards in the electrical properties that, the drive should be less than 2500pF load capacitance. (3) the interface signals RS-232C Figure 2-2 RS-232 leads feet Figure RS-232C conventional standards interface 25 lines, four lines of data, 11 Line of Control, 3 regular lines, 7 standby and missing lines, commonly used only nine roots, and they are : Liaison control signal lines : Data ready devices (Data set ready-DSR) - effective (on) state that could be used modem in the state. Data terminal ready (Data Terminal ready-DTR) - effective (on) state that data terminals can be used. Sometimes even to the power of these two signals, one on the call immediately effective. Two state signals effective equipment, but indicated that the equipment itself could be used, does not indicate a communication link can initiate communication can begin by following communication to the control signals. Request sent (Request to send-RTS) - used to express DTE DCE request sent data to be sent when data terminals, so that a signal (on state), a request sent to modem. It is used to control access to state modem. Allow transmission (Clear to send-CTS) - used to express DCE DTE made ready to receive the data signal is sent to request the response RTS signal. When modem is ready to receive data transmitted from terminal, and move to, so that the effective signal to inform terminals begin sending data along the lines TXD sending data. This request received RTS/CTS contact signal is sent to 3,600-4,000 modem system between the cut over ways and means to receive. In Full two-way work system for transmission and reception of way between the cut over. In Full two-way work system for the allocation of two-way routes, so there is no need RTS/CTS contact signals to change high. Receive line signals departure clearance (Beijing Line detection-RLSD) - used to express DCE has connected communications links to inform DTE ready to receive data. When local modem received by the other side of communication links (distant) modem sent to the carrier signal, the signal RLSD effective, informed terminal ready to receive, and will receive from modem demodulate signals from the carrier into the digital traffic data, along RXD line toreceive data terminals. The line is also known as data carrier departure clearance (Data carrier detection-DCD) line. Ringing instructions (Ringing-RI) - When modem sent the switchboard received Ringing call sign, signal to the effective (on state), informed terminals have been shouting. Send and receive data lines : Send data (Transmitted data-TXD) - through TXD serial data terminals will be sent to modem, (DTEDCE)。 Receiving data (Beijing data-RXD) - through RXD line terminals receive data from modem made to the serial，(DCEDTE)。 Earth There are two lines SG, PG- signal to the signal line and the protection, without direction. The control signal line when effective, and when the order expressed interface signal transmission process. For example, only when DSR and DTR are in the effective (on) status, can be transmitted between the DTE and DCE operation. If the DTE to send data, the advance will buy into effective DTR line (on) status, such as CTS line received effective (on) of the answer, can send serial data at TXD line. This sequence of the provisions of Half of the two-way work lines of communication particularly useful because duplex communication can be determined by the DCE to receive directions to the direction of this line can begin sending. RS-232通信協(xié)議及接口標(biāo)準(zhǔn) RS-232C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RS-232標(biāo)準(zhǔn)的基礎(chǔ)上經(jīng)過(guò)改進(jìn)而形成的。RS-232C是美國(guó)EIA(電子工業(yè)聯(lián)合會(huì))與BELL等公司一起開發(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RS-232C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RS-232C接口標(biāo)準(zhǔn)的內(nèi)容之前，先說(shuō)明兩點(diǎn)： 首先，RS-232C標(biāo)準(zhǔn)最初是遠(yuǎn)程通信連接數(shù)據(jù)終端設(shè)備DTE(Data Terminal Equipment)與數(shù)據(jù)通信設(shè)備DCE（Data Communication Equipment）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)RS-232C標(biāo)準(zhǔn)與計(jì)算機(jī)不兼容的地方就不難理解了。 其次，RS-232C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。 RS-232C接口標(biāo)準(zhǔn) RS-232C標(biāo)準(zhǔn)(協(xié)議)的全稱是EIA-RS-232標(biāo)準(zhǔn), 其中EIA(Electronic Industry Association)代表美國(guó)電子工業(yè)協(xié)會(huì)，RS（Recommeded standard）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EIARS-232-C、EIARS-422-A、EIARS-423A、EIARS-485。 這里只介紹EIARS-232-C（簡(jiǎn)稱232，RS232）。 例如，目前在IBM PC機(jī)上的COM1、COM2接口，就是RS-232C接口。 (1) 電氣特性 EIA-RS-232C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1(MARK)=-3V-15V，邏輯0(SPACE)=+315V 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）+3V+15V，信號(hào)無(wú)效（斷開，OFF狀態(tài)，負(fù)電壓）=-3V-15V 以上規(guī)定說(shuō)明了RS-323C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-3+3V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(315)V之間。 （2） 連接器的機(jī)械特性 由于RS-232C并未定義連接器的物理特性，因此，出現(xiàn)了DB-25、DB-15和DB-9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）DB-25連接器 PC和XT機(jī)采用DB-25型連接器。DB-25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）2，3，4，5，6，7，8，20，22 20mA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IBM PC和IBM PC/XT機(jī)提供，至AT機(jī)及以后，已不支持。 2）DB-9連接器 在AT機(jī)及以后，不支持20mA電流環(huán)接口，使用DB-9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)。DB-25型連接器的引腳分配與DB-25型引腳信號(hào)完全不同。因此，若與配接DB-25型連接器的DCE設(shè)備連接，必須使用專門的電纜線。 電纜長(zhǎng)度：在通信速率低于20kb/s時(shí)，RS-232C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：RS-232C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）。可見這個(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） RS-232C的接口信號(hào)圖2-2 RS-23