本文首先对单片机和PLC的基本含义进行简要阐述；其次从接口电路设计、RS—232C串行通信接口的设置、 通信协议设计三个方面入手，对单片机与PLC串行口通信接口电路及设置进行探究；然后从发送命令帧格式、响应帧格式两 方面，提出单片机与PLC串行口的通信过程，提出单片机与PLC 的应用措施。

This paper describes the SCM and PLC briefly; and then explores on the serial communication interface circuit between SCM and PLC from three aspects which are the interface circuit design, setup of the RS - 232 c serial communication interface and communication protocol design. From the sending command frame format and the responsing frame format, it proposes the serial communication process between SCM and PLC, and proposes their application.