GE IC693CMM321是GE品牌的以太网通讯模块，主要用于PLC控制系统中。在PLC的用户程序中，主程序起着核心作用。每个扫描周期，CPU都会调用一次主程序。主程序可以调用子程序，进行小型控制系统的编程。在某些情况下，中断程序用于快速响应中断事件。当中断事件发生时，CPU将停止执行当前任务，转而执行用户编写的中断程序。

It is a GE brand Ethernet communication module mainly used in PLC control systems. In the user program of PLC, the main program plays a core role. Each scan cycle, the CPU will call the main program once. The main program can call subroutines for programming small control systems. In some cases, interrupt programs are used to quickly respond to interrupt events. When an interrupt event occurs, the CPU will stop executing the current task and instead execute the interrupt program written by the user.