DCS PLC network communication

Those who can understand it are not ordinary people; even senior engineers may not all understand it.

Looking up each of these words on Baidu Baike will provide a basic understanding

Communication between DCS and PLCs has been done using the Modbus protocol as well as the RS485 bus; other methods haven’t been used much. As for this 232 interface, it’s used to connect to a computer via software, right?

I only remember the categories: field-level communication network, control-level communication network, and management-level communication network. But there are so many different communication protocols that I’ve never been able to figure out which one should be used in which situation

There are many types of communication between DCS and PLCs, and different protocols are used for communicating with PLCs from various manufacturers. The most common one is certainly 458 communication (although it isn’t the most widely used). The CAN bus is rarely used in the industrial control field; it is mainly used in the automotive industry. Since PLC manufacturers have developed numerous proprietary communication protocols, the most widely used ones are Siemens’ Profibus and Profinet; these protocols are only supported by Siemens’ PLCs, and a corresponding card is required for DCS systems. Additionally, Modbus is used; Modbus.net and TCP/IP are also quite common. PLCs may require additional cards, as do DCS systems. Once these cards are configured and the hardware is connected, communication can be established. Modbus is the most common communication protocol. Internal communication in DCS systems is generally based on the TCP/IP protocol over switches; some systems also use encryption through firewalls. Ordinary PLCs do not support this protocol, so... as for communication protocols*, there are no textbooks available, so I can only give a brief explanation. But I need to leave now; I’ll continue discussing this tomorrow if I remember.

In actual project work, very advanced concepts are generally not necessary. All that’s required is for the DCS and PLC to agree on the communication protocol – such as Modbus RTU based on RS485 or Profibus DP. Once both sides have agreed on parameters like station addresses and baud rates, it’s sufficient to make the necessary configurations using their respective software; it’s that simple\ud83d\ude01

If you want to understand the principles of communication, it’s very difficult, as mentioned on the second floor. If you are involved in new product development, you need to study thoroughly; if you only work on projects, it’s sufficient to just know how to use them.