摘要
在使用PLC进行电气控制时,有时必须了解PLC的工作原理,才能达到满意的控制效果。笔者介绍了PLC的工作原理,然后从PLC工作原理的角度,讨论了继电器电路与PLC梯形图的逻辑等效性问题,和输入信号变化频率与扫描周期的关系,并给出了PLC输入脉冲的最高频率计算方法。讨论了I/O响应时间与扫描周期的关系,给出了最大I/O响应时间计算方法,最后讨论了定时精度与扫描周期的关系,分析了定时器的最大误差。
Understanded the operating principle of PLC sometimes at the time of using PLC to control electrically, could reach the satisfied control result. This paper introduces the operating principle of PLC, then from the point of the PLC operating principle, it discusses the problem of logic equivalence between relay circuit and PLC ladder diagram, and the releationship between changing frequency of inputting pulse. It discusses the releationship between I/O response time and scan time, provides a way to calculate the maximal I/O response time, and the releationship between time accuracy and scan time. At last analysing the maximal error of Timer.
出处
《华东地质学院学报》
2003年第3期298-300,共3页
Journal of East China Geological Institute
