About DCS and PLC

The PLC said something like “Bara bara, little fairy, transform!” and then it became a DCS

The PLC is a controller, an isolated product. DCS is the system

It can be said that DCS is more suited for process control, while PLC is more suitable for logical control; however, with the development of PLCs, they are now capable of replacing DCS in terms of functionality.

Hehe, what the person upstairs said – it seems like the process control isn’t logical at all; it doesn’t resemble logical control at all.... :lol

I understand that DCS is a software and hardware testing and control platform built on the basis of industrial computers; it is a computer expansion system that cannot operate independently. It is designed for situations where there are a large number of tasks that need to be monitored and controlled. On the other hand, a PLC is a micro control computer with its own operating system, capable of operating independently as well as being expandable. It has its own programming language, and it is intended for use in situations where there are a smaller number of tasks that need to be monitored and controlled. PLC is essentially an intermediate product between microcontroller-based control systems and computer-based control systems; it provides a software and hardware platform for further development. PLCs with simple functions cost just a few hundred yuan and are available for sale on Taobao. Due to the significant improvement in the processing capabilities of IC chips, microcontroller control systems, PLC control systems, and DCS control systems have seen their boundaries becoming increasingly blurred.

PLCs and DCSs are becoming increasingly similar; the inherent differences between them are shrinking, and they are moving closer to each other. DCSs have advantages in analog control, database storage, and multi-point control, while PLCs excel in logical control

Early PLCs were developed as a replacement for relay-contactor systems; therefore, early PLCs were used for logical control； Early DCS systems were developed as a replacement for analog instruments; therefore, they were used for analog control ； Later, PLC systems added and developed analog signal processing capabilities, evolving from stand-alone units to networked systems ； The DCS system has added and developed logical processing functions. The PLC system is an open system, meaning PLCs from various manufacturers that comply with communication protocols can be integrated into it ； The DCS system is a closed system, with external connections mostly achieved through OPC technology. It can be said that the two systems originate from different backgrounds, but as they move toward the same goal, the differences between them are becoming increasingly small.

DCS is a “distributed control system,” while PLC (Programmable Logic Controller) is merely a control “device”; the difference between the two is that one is a “system” and the other is a “device.” The system can enable the functions and coordination of any device, while the PLC device only performs the functions specific to its own unit.

PLC technology has also developed rapidly, with larger scales and the ability to control analog signals as well.

Take a look at this article; it’s written in great detail: https://www.sohu.com/a/311307923_120129629?sec=wd