This paper introduces the principle of Programmable Logic Controller, analyses the process of PLC and develops interpretive program based on C language, realizes a lot of basal functions of PLC.

• 从可编程控制器的基本原理出发，详细分析了PLC的工作过程，开发出了以C语言为基础的指令解释程序，实现了PLC的许多基本功能。