IC693PWR321 GE

The actual physical quantities,in addition to switch quantities,analog quantities,and motion control.For example,the displacement of machine tool components is often expressed in digital quantities.Motion control,the effective method is NC,that is,digital control technology.This is a computer-based control technology that was born in the United States in the 1950s.Today it is very popular and perfect.At present,the numerical control ratio of metal cutting machine tools in advanced countries has exceeded 40%to 80%,and some are even higher.PLC is also a computer-based technology and is becoming increasingly sophisticated.The PLC can receive counting pulses,and the frequency can be as high as several k to several tens of KHz.Some PLCs also have a pulse output function,and the pulse frequency can also reach tens of k.With these two functions,plus the PLC has data processing and computing capabilities,if it is equipped with corresponding sensors(such as rotary encoders)or pulse servos If the device is installed,all kinds of control can be realized completely according to the principle of NC.High-end and mid-range PLCs are also developed with NC units,or motion units,which can realize point control.The motion unit can also realize curve interpolation,which can control the curve movement.Therefore,if the PLC is equipped with this kind of unit,the digital quantity control can be carried out completely by the NC method.The newly developed motion unit has even released the programming language of NC technology,which provides convenience for better digital control with PLC.

实际的物理量，除了开关量、模拟量，还有运动控制。如机床部件的位移，常以数字量表示。运动控制，有效的办法是NC，即数字控制技术。这是50年代诞生于美国的基于计算机的控制技术。当今已很普及，并也很完善。目前，先进国家的金属切削机床，数控化的比率已超过40％～80％，有的甚至更高。PLC也是基于计算机的技术，并日益完善。PLC可接收计数脉冲，频率可高达几k到几十k赫兹，可用多种方式接收这脉冲，还可多路接收。有的PLC还有脉冲输出功能，脉冲频率也可达几十k，有了这两种功能，加上PLC有数据处理及运算能力，若再配备相应的传感器（如旋转编码器）或脉冲伺服装置，则完全可以依NC的原理实现种种控制。高、中档的PLC，还开发有NC单元，或运动单元，可实现点位控制。运动单元还可实现曲线插补，可控制曲线运动。所以，若PLC配置了这种单元，则完全可以用NC的办法，进行数字量的控制。新开发的运动单元，甚至还发行了NC技术的编程语言，为更好地用PLC进行数字控制提供了方便。