中英文翻译--RS-232通信协议及接口标准【适用于毕业论文外文翻译】.doc
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1、英文文献 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), togethe
2、r 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 c
3、learly 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 point
4、s : 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
5、 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 co
6、mputer 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
7、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 standa
8、rd), 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 als
9、o 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 char
10、acteristics, 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 n
11、egative 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, b
12、reak 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
13、 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
14、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
15、,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
16、 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 allo
17、cation 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
18、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 pro
19、perties 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
20、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 si
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