可编程序控制器顺序逻辑梯形图的简易设计法

本文提出一种设计可编程序控制器(PLC)顺序逻辑梯形图的简易方法。其步骤是:根据受控设备的工况示意图和工步状态表,制定一张PLC顺序逻辑控制系统输入输出状态表,然后分析状态表内所列出的受控机械动作与检测信号之间是否存在逻辑矛盾,如果存在,则借助设置辅助继电器来消除逻辑矛盾。在此基础上,根据输出状态逻辑式正确性的充要条件,在状态表内直观地确定每个PLC受控元件的输出状态逻辑式,最后根据逻辑式绘制梯形图。

Simple and Easy Method for Designing Sequence Logic Ladder Diagram of Programmable Controller

In this paper, the autnor suggests a simple and easy method for designing sequence logic ladder diagram of programmable controller(PLC). Its procedures are as follows: Firstly, according to the operating mode diagrammatic sketch and working step condition table of the controlled equipment,make a list of I/O condition table for the PLC sequence logic control system.Analyse then whether any logic contradiction exists between the controlled mechanical acts and the detection signals which are listed in the condition table.It is necessary to eliminate the logic contradietions by setting relief relay if some logic contradictions appear.On the basis of above, according to the sufficient and necessary conditions on the rightness of the output condition logic equation,determine visually,in the condition table, the output condition logic equation of every controlled element of the PLC.Finally,according to the logic equations draw the ladder iagram.