虚拟硬继电器在可编程控制器课程中的应用

Application of Virtual Hard Relay in PLC Course

针对可编程控制器(PLC)开关量输入/输出模块的电路特点,提出虚拟硬继电器模型,将每个开关量输入端或输出端的内部接口电路等效成一个虚拟的硬继电器。教学实践表明,运用虚拟硬继电器模型学生能牢固掌握PLC数字控制系统的外部接线,清晰理解PLC的工作原理,为梯形图编程打下良好基础。

According to the characteristics of the programmable logic controller(PLC)digital I/O module,a virtual hard-relay model is proposed.The internal interface circuit of each digital input or output port is equivalent to a virtual hard-relay.The teaching practice shows that,by using virtual hard relay model,students can firmly grasp the external wiring of the PLC digital control system and clearly understand the working principles of PLC,which lay a good foundation for the ladder diagram programming.