串行通信接口标准经过使用和发展，目前已经有几种。但都是在RS-232标准的基础上

经过改进而形成的。所以，以RS-232C为主来讨论。RS-323C 标准是美国EIA(电子工业联合

会）与BELL等公司一起开发的1969 年公布的通信协议。它适合于数据传输速率在0～

20000b/s 范围内的通信。这个标准对串行通信接口的有关问题，如信号线功能、电器特性

都作了明确规定。由于通行设备厂商都生产与RS-232C制式兼容的通信设备，因此，它作为

一种标准，目前已在微机通信接口中广泛采用。-Serial communication interface standard through the use and development, now has several. But they are in the RS-232 standard based on an improved formed. Therefore, to RS-232C-oriented discussion. RS-323C standard is the United States EIA (Electronic Industry Association) and BELL and other companies in 1969 announced the development of communication protocols. It is suitable for data transfer rate in the 0 ~ 20000b/s within the scope of communication. The standard serial communication interface of the relevant issues, such as the signal line features, electrical characteristics have been clearly defined. Since the passage of equipment manufacturers have production and standard RS-232C compatible communications equipment, so that it as a standard has been in the computer communication interface is widely used.