This paper makes a comparision between most useful series interface-RS-422 and RS-423, and primarily introduces the method of constituting RS-422 series interface by use of either foreign or domestic IC chip and the examples of its practical application in industrial control. 本文对常用的几种串行接口-RS-232C、RS-422、RS-423做了对比分析,重点介绍了应用国内、外的集成电路芯片组成RS-422接口的方法,及其在工业控制中的应用实例。