PLC与DCS有什么区别?(What is the difference between PLC and DCS?)

  Plc擅长逻辑控制,如实现电路的逻辑控制,属于高压设备,主要用于控制电机的启停等。Dcs擅长模拟控制,属于弱项设备,主要用于液位、流量、温度的模拟控制。(初学者可以结合plc视频教程来学习)

  可编程控制器和集散控制系统在发展初期是由两种技术人员开发的,他们面对不同的控制对象。PLC主要针对汽车制造,模拟量很少或没有。开发人员主要是电气技术人员,用计算机逻辑运算代替继电器逻辑。后来DCS引入市场,由原来的仪表技术人员开发。它在运算放大器的基础上,用计算机模拟运算代替了原来的模拟运算。两者的研究内容不同。DCS最早应用于石化系统,后来两者都想占领市场。PLC增加了模拟量的运算,DCS发展了逻辑运算。但是,两者在新开发的零件上都存在一些缺陷。PLC开发的模拟运算功能块少,编程比较复杂,价格也比较贵。每个电路的成本约为2300美元,DCS开发的逻辑运算需要几十毫秒才能完成一次与非门运算,而PLC只需要几分之一毫秒。

  在维护方面,DCS维护成本高,对接地电阻要求严格,经常因为接地电阻达不到要求而烧坏模块。PLC不要求严格的接地电阻,所以维护成本相对较低。

  因此,如果模拟量较多,需要先进的控制方案,如专家系统、模型控制、DCS等。如果开关较多,建议使用PLC。本文来源:https://www.jcpeixun.com

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PLC is good at logic control, such as realizing the logic control of the circuit. It belongs to high-voltage equipment and is mainly used to control the start and stop of the motor. DCS is good at analog control and belongs to weak equipment. It is mainly used for analog control of liquid level, flow and temperature. (beginners can learn with PLC video tutorial)

Programmable controller and distributed control system were developed by two kinds of technicians in the early stage of development. They face different control objects. PLC is mainly aimed at automobile manufacturing, with little or no analog quantity. The developers are mainly electrical technicians, who use computer logic operation to replace relay logic. Later, DCS was introduced into the market and developed by the original instrument technicians. It replaces the original analog operation with computer analog operation on the basis of operational amplifier. The research contents of the two are different. DCS was first used in petrochemical system, and later both wanted to occupy the market. PLC increases the operation of analog quantity, and DCS develops logic operation. However, both of them have some defects in the newly developed parts. The analog operation function block developed by PLC is less, the programming is more complex and the price is more expensive. The cost of each circuit is about $2300. The logic operation developed by DCs takes tens of milliseconds to complete a NAND gate operation, while PLC only takes a fraction of a millisecond.

In terms of maintenance, DCs has high maintenance cost and strict requirements for grounding resistance. Modules are often burned out because the grounding resistance fails to meet the requirements. PLC does not require strict grounding resistance, so the maintenance cost is relatively low.

Therefore, if there are many analog quantities, advanced control schemes are needed, such as expert system, model control, DCS, etc. If there are many switches, PLC is recommended. Source: https://www.jcpeixun.com