DCS和PLC区别总结的比较好的一篇文章

The Difference Between

DCS and PLC

In the power plant automation in thermal field, DCS and PLC is two completely different and have something to the concept of contact. DCS and PLC is computer technology and industrial control technology, the combination of the power of the main engine control system, and is with DCS PLC is mainly applied in the power plant auxiliary workshop. DCS and PLC has operator station provides the means of human-computer interaction, rely on the controller based on computer technology to complete control operation, all through the I/O card finished and a component and execution of the device data exchange, has called network communications system. DCS and PLC so similar, why there is a completely different concept in engineering practice, we how to choose? This paper, from the historical evolution, technical features, development direction and so on several aspects are reviewed in this paper, the hope can be reference for the thermal professionals. The DCS in NETWORK6000 + as an example, the paper tries to detailed clear examples.

1 The history and core concept of DCS and PLC

DCS for DISTRIBUTED CONTROL SYSTEM. Refers to the dangerous scattered and data set. 70 s to enter the market, complete the analog control with PID operation, instead of the simulation mainly control instrument. First proposed a kind of such thoughts of DCS instrument manufacturers, at that time is mainly used in chemical industry. And in the 60 s PLC successfully developed, called the Logic

operation of the PLC (Programmable Controller), based as PLC. Mainly is used in automobile manufacturing.

DCS and design principle of large difference with PLC, PLC touch the relay copy from the control principle of the rise and development of the 70 s, only the switch quantity logic control of PLC. It’s to store to perform the logic operation, sequence control, timing, counting and operation of the operation instructions; And through the digital input and output operation, to control all kinds of mechanical or production process. Users of the production process control program to express the process requirement. Will it in the PLC program memory, the runtime users according to store the content of the program execution to complete ideally suited to process the required action.

DCS operational amplifier is in on the basis of the development of may. Put all the function, the relationship between the various process variables are successful design can block. In the mid 70's,the DCS only analog control.

DCS and PLC controller is the main difference in the switch quantity and analog computing, even if later both mutual some penetration, but there are still differences. Since the 80 s, PLC logical operations outside, also in addition to adding some control circuit algorithm, but to complete some complex operation or more difficult with ladder-diagram programming, PLC, analog computing when programming in not too, intuitive, and programming is more troublesome. But in the solution in logic, show the advantages of fast. And DCS use function of packaging simulation calculation and logic operations, whether logic operation or complex simulation of operation forms of expression are very clear, but relatively PLC for the expression of the logical operation efficiency is low.

DCS and PLC in the historical evolution differences is obvious, their subsequent had a great influence. However, the greatest impact on subsequent development, and not the difference in origin technology, but its origin, the