可编程序控制器中定时器的应用设计

The Application Design of Timer in PLC

给出了定时器的定时设定输出、平衡和不平衡振荡信号发生器、定时器设定时间设置等基本环节 ,并讨论了它们的应用———在液位控制系统中 ,采用一个液位开关和定时器控制进料或出料阀 ;在时间比例控制中 ,用不平衡振荡发生器调节占空比 ;在pH控制中 ,采用定时器实现与采样控制相类似的控制 ;在信号报警系统中 ,通过改变定时器设定值来调整声光报警信号的频率。

Some basic aspects such as timer output, balance and unbalance square signal generator, timer setting, and so on are provided in the paper The applications are also discussed in this paper: In a level control system, a level switch and timer may be used to manipulate input or output valve automatically; In the time rate control system, unbalance square signal generator can be used to control the rate of open or close time; In the pH control system, timer can often be used to get a good control effects which is similar to a sampling control system; In an alarm system, timer setting can be adjusted to change the alarm signal frequency for the alarm signal identification. Some attentions of design and application are discussed yet in this paper.