What does PLC networking mean? Common PLC networking methods are classified

Data interaction is required between PLCs, between PLCs and computers, and between PLCs and intelligent devices, especially in some remote control and decentralized control situations. This places higher demands on PLC data interaction and networking functions. Common PLC networking methods can be roughly summarized as three types: based on universal serial ports, based on dedicated buses, and based on Ethernet.

1. Universal serial port module

The network connection is realized based on the serial communication module, which adopts the form of computer link. The corresponding settings are made in the configuration software of the host computer. It can communicate with multiple PLCs without programming.

2. Based on dedicated bus

At present, PLC manufacturers have provided dedicated network systems for their PLC products. Due to the exclusivity of the manufacturers' products, devices from different manufacturers cannot communicate with each other. Basically, if a manufacturer's PLC is selected, other supporting equipment must also be from that manufacturer. The cost is relatively high, so there are certain limitations in application.

3. Based on standard industrial Ethernet

Based on the standard industrial Ethernet networking method, the system is generally divided into three levels: the first level is the host computer monitoring station composed of industrial computers; the second level is the industrial Ethernet composed of hubs, twisted pair cables and transceivers; the third level is the control station, which selects TCP/IP as the communication protocol and adopts the C/S mode to enable the control station and the monitoring station to achieve connection-oriented communication.

In comparison, it is recommended that you use Ethernet networking. The advantage of this networking method is that it can use the existing factory LAN, improve the comprehensive utilization rate, and has a fast speed. The Ethernet communication rate can reach 100Mbps; if optical fiber transmission is used, the anti-interference ability is greatly enhanced, and the transmission distance can reach tens of kilometers. However, Ethernet cannot communicate directly with serial devices such as PLC, and must be equipped with related equipment to achieve communication, which increases the cost of use. It is not common in general small and medium-sized control systems.