The main function of PLC remote monitoring module

The Industrial Internet of Things integrates various sensors and control units with perception and monitoring capabilities, Internet communications, intelligent analysis and other technologies into all aspects of the industrial production process, thereby greatly improving manufacturing efficiency, improving product quality, reducing product costs and resource consumption, and ultimately achieving intelligence.

PLC control system is an industrial control unit, which is used to replace relays, execute logic, timekeeping, counting and other sequential control functions. It is widely used in industrial systems because of its strong versatility, easy use, wide adaptability, high reliability, strong anti-interference ability and simple programming.

There is a big branch in the industrial Internet of Things, which is to integrate the PLC control system into the Internet of Things system. PLC is a traditional industrial control unit. The system communication only involves a workshop or factory area, and the data is exchanged within the local area network. To realize the PLC Internet of Things, the first thing is to be able to remotely exchange data with the PLC through the Internet. The current mainstream technology is to bridge the PLC and the Internet through the PLC remote monitoring module. There are still very few PLCs with built-in Internet communication.

The main function of the PLC remote monitoring module is to realize the conversion between the PLC's industrial communication protocol and the Internet's general protocol, to establish a real-time data interaction channel between the remote central control system and the PLC system. The central control system uses data processing technology to realize data analysis, storage, and feedback control of the front-end PLC system.

The core functions of the PLC remote monitoring module are as follows:

It is necessary to solve the protocol conversion and network communication of PLCs of various brands and models on site.

Solve the network node problem, so that the remote data processing system can be quickly and easily connected to the front-end PLC and maintain stable communication.

To realize these two functions, the PLC remote module manufacturers need to have a very in-depth study of the industrial control industry and master the protocols of various types of PLCs (Siemens, Mitsubishi, Omron, AB, Schneider, Beckhoff, Delta, Xinje, etc.), so that they can be used in different sites. In addition, the manufacturers need to have a deep technical foundation in protocol conversion and network communication. That is, both the industrial control and IT industries need to have a deep technical foundation.

The current mainstream technology for PLC remote modules is to transfer through cloud servers, which uses domain name identification technology. There is no need for a fixed IP. The register address of the PLC is mapped on the server through the network. The central control system accesses the cloud server, generally using the OPC protocol or the HTTPS protocol. In this way, the two sides can quickly form a network connection, and the PLC and network protocol conversions are automatically converted by the module. The front-end configuration engineers only need to understand the PLC protocol, and the back-end central control system engineers only need to understand the general OPC protocol or the HTTPS protocol. Engineers on both sides can work independently. A project can be implemented separately.

This type of PLC remote module has many additional functions, because the module uses variable mapping registers to extract data, so that variables can be called to do mobile phone APP, web page monitoring, realize mobile terminal monitoring function, and can also do SMS/WeChat alarm, telephone dial alarm.

There are some other remote modules on the market, such as VPN, which only forms a network transparent transmission channel. In this way, the software protocol of the central control room needs to support PLC, and there is no way to develop mobile APP and web monitoring. In this way, the central control system generally needs to use traditional automatic control software and configuration software. It is more troublesome to develop the central control system by yourself using C++, PHYSON, and JAVA. Because programmers generally do not know the industrial control protocol. The flexibility is relatively poor.