Differences between DCS and PLC
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Recently, I was working on a PID diagram for the thermal system of a thermal power plant. Our chief engineer kept saying, “Use DCS for this part; there’s no need to use it for that small section – PLC is sufficient.” I was already a bit confused about these two concepts, and his words only made things more confusing. So I’d like to discuss with everyone what the difference between these two actually is What exactly does the intuitive concept of whether to use DCS for a project mean?
PLC control and DCS control systems are not concepts at the same logical level; a PLC can make up a DCS. Of course, there are still performance differences between the two; it depends on the specific product and requirements.
Baidu says the same thing. I’d like to learn more about it. For example, in a boiler room, the control room doesn’t have a computer; instead, there is a large control panel with many buttons and instruments, as well as alarm signals such as audible alerts when the water level is too high. This control panel is used to control the operation of the boiler, including starting and stopping it. Is this a DCS?
DCS is a distributed control system that incorporates all control points into a computer-based control system, whereas PLCs are used for logical control at a single point or a few points; when the number of such points is small, there is no need to use a DCS. Nowadays, thermal power plants are quite large, which is why DCS is used in them
DCS is a distributed control system that focuses on control systems, with inputs and outputs mainly being analog signals； A PLC is a programmable logic controller, primarily used for electrical control, and mainly outputs digital signal switches. However, currently there is a trend toward their integration with each other.......
The first version of PLCs was used for small systems; PLCs were employed to control various complete units, heating furnaces, and other equipment. If the entire plant is designed with a large number of points, DCS is definitely the choice
Thank you. I talked to the instrumentation team at my company later, and they gave a more or less similar explanation: lol. They also said that DCS is relatively expensive