PM866K02 ABB

The switch quantity is also called the logical quantity,which means that there are only two values,0 or 1,ON or OFF.It is the most commonly used control,and controlling it is the advantage of PLC and the most basic application of PLC.

The purpose of switch quantity control is to make PLC generate corresponding switch quantity output according to the current input combination of switch quantity and historical input sequence,so that the system can work in a certain order.Therefore,it is sometimes called sequential control.

The sequence control is divided into manual,semi-automatic or automatic.The control principles used are decentralized,centralized and mixed control.

开关量也称逻辑量，指仅有两个取值，0或1、ON或OFF。它是最常用的控制，对它进行控制是PLC的优势，也是PLC最基本的应用。

开关量控制的目的是，根据开关量的当前输入组合与历史的输入顺序，使PLC产生相应的开关量输出，以使系统能按一定的顺序工作。所以，有时也称其为顺序控制。

而顺序控制又分为手动、半自动或自动。而采用的控制原则有分散、集中与混合控制三种。