3BSE029807R100 ABB

In the manufacturing industries characterized by changes in geometry and mechanical properties and in the process industries characterized by physical and chemical changes that convert raw materials into products,in addition to feedback control based on continuous quantities,especially in the manufacturing industry,there are A large number of switch-based open-loop sequential control,which performs sequential actions according to logical conditions and acts in accordance with the sequence;in addition,there are also chain protection actions that have nothing to do with the sequence and timing according to the logic relationship control;and a large number of switches,Pulse quantity,timing,counter,over-limit alarm of analog quantity and other state quantity-based data collection and monitoring of discrete quantity.Due to these control and monitoring requirements,PLC has developed into a product that replaces relay circuits and performs sequential control.In many years of production practice,PLC,DCS and IPC have gradually formed a three-legged situation,and other single-loop intelligent regulators occupy a certain percentage in the market.

在以改变几何形状和机械性能为特征的制造工业和以物理变化和化学变化将原料转化成产品为特征的过程工业中，除了以连续量为主的反馈控制外，特别在制造工业中存在了大量的开关量为主的开环的顺序控制，它按照逻辑条件进行顺序动作号按照时序动作;另外还有与顺序、时序无关的按照逻辑关系进行连锁保护动作的控制;以及大量的开关量、脉冲量、计时、计数器、模拟量的越限报警等状态量为主的—离散量的数据采集监视。由于这些控制和监视的要求，所以PLC发展成了取代继电器线路和进行顺序控制为主的产品。在多年的生产实践中，逐渐形成了PLC、DCS与IPC三足鼎立之势，还有其它的单回路智能式调节器等在市场上占一定的百分比。