PLC的数字量I/O连接之电流回路分析法

Analysis of Current Loop in PLC Digital IO Connections

针对PLC的数字量I/O连接问题,文章从电流流向及有效电平的概念入手,摒弃"源型漏型"的说法,提出"放之四海而皆准"的电流回路分析法,结合不同厂家的PLC与变频器具体连接实例说明该方法的应用,对PLC的数字量I/O连接达到有效的指导。

For the PLC digital I/O connectivity issues,this article starts from the concept of current flow and the effective level,gets rid of “source-drain type” argument,and proposes “one size fits all” current loop.Combing with the application of this method in the concrete connection between PLC and inverter.this paper aims to provide effective guidance for the PLC digital I/O connection.