PLC实现顺序控制的编程方法

Programming Method of PLC′s Sequential Control

顺序控制在工业控制中是一种常见的控制，PLC实现顺序控制的主要任务就是用户程序的设计，本文以日本三菱F1系列小型可编程序控制器为例，讲述了用基本逻辑指令，移位寄存器，步进梯形指令三种编程方法，由于各厂家生产的PLC都有基本逻辑指令，因而用基本逻辑指令编辑较为广泛，但一般程序较为烦琐，不易检查，本文的方法较为清晰，易于掌握，用移位寄存器对单一序列易于控制，对其它的控制较为困难，用步进梯形指令编程最为简单直观，但一些型号的PLC没有该指令，受到一定的限制，因此三种编程方法各有其特点，可根据控制对象具体情况来选择控制方法。

Sequence control is a common method in industrial control. The main task of PLC realizing sequence control is to developa program for the users. This article takes a series of Japanese small-sized Programming Control of Mitsubishi as examples, and three basic programming methods — basic logical instructions, shifting register and step ladder are discussed. Because every company's PLC has basic logic instructions, programming with them is very common. But general program are complicated and difficult to be checked. The methods discussed here are clear and easy to grasp. Using shifting register to control single sequence is very easy, but difficult to other control methods. Programming with step ladder is the easiest and directly perceived. However, some types of PLC don't have such instructions, so this method sometimes can not be brought into the full play. Therefore, each of the programming methods has their own features. We can choose proper programming method according to controlling targets and concrete situation.