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






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: