根据系统功能的要求，主站需发送2种类型的命令：（1）同期命令，它由定时器触发引起，每隔ls周期发送1次；（2）非周期性命令，它由操作者按动相应命令按钮引起，非周期性发送。自动监控系统软件安装在主站上，而通信程序作为自动监控系统软件的一部分也安装在主站上。 -According to the system functional requirements, the main points need to send 2 types of commands: (1) In the same order, it is triggered by a timer triggered every cycle to send 1 ls　(2) aperiodic order, which by the operator by caused by moving the appropriate command button, non-cyclical sending. Automatic monitoring system software installed in the main station, while the communication process as part of automatic control system software is also installed in the main station.