The implementation of PLC remote control usually involves two levels, hardware and software, and requires the use of a variety of technologies and equipment to achieve it. The following are its common implementation methods:
Hardware level
PLC equipment: It is required to have a communication interface, such as Ethernet interface, RS485 interface, etc., to transmit data with other devices. Some high-end PLCs also support wireless communication modules, such as 4G, 5G, WiFi, etc., and can be directly connected to a remote server or terminal through a wireless network.
Communication network
Wired network: Connect the PLC to network devices such as switches and routers through Ethernet cables to form a local area network, and then connect to the Internet through gateways, firewalls and other devices to achieve remote access. This method has high stability and fast data transmission speed, and is suitable for industrial scenarios with high reliability requirements.
Wireless network: Use cellular networks such as 4G and 5G or WiFi networks to connect PLC to remote servers or terminals. 4G and 5G networks have a wide coverage range and can achieve long-distance remote control. They are suitable for some scenarios where on-site wiring is difficult or mobile monitoring is required; WiFi networks are suitable for wireless communications within a certain range, such as local areas inside factories.
Remote terminal device: can be a computer, smartphone, tablet, etc. These devices need to have corresponding communication functions, such as supporting Ethernet, WiFi, 4G/5G and other network connection methods, in order to communicate with PLC.
Software level
PLC programming software: used to program and configure PLC, set communication parameters, define data transmission format and protocol, etc. Through the programming software, the functional modules and logic programs required for remote control can be downloaded to the PLC, so that it can communicate and interact with remote devices according to the set rules.
Communication protocol
Standard communication protocol: such as Modbus, OPC, etc. Modbus protocol is a widely used serial communication protocol that can realize simple data transmission between PLC and other devices; OPC (OLE for Process Control) protocol is an industrial standard communication protocol based on COM/DCOM technology, which is used to achieve interoperability between devices from different manufacturers, and can easily transmit PLC data to the host computer monitoring system or other applications.
Dedicated communication protocol: Some PLC manufacturers will also develop their own dedicated communication protocols to achieve more efficient and safer communication. For example, Siemens’ S7 protocol and Mitsubishi’s MC protocol are usually closely integrated with the manufacturer’s PLC equipment and programming software, providing richer functions and better compatibility.
Remote monitoring software: installed on the remote terminal device, used for communication and data interaction with the PLC. These software usually have a friendly user interface and can realize real-time monitoring, data acquisition, remote programming and debugging of the PLC.
Security and management
User authentication and authorization: The identity of remote access users is authenticated by setting user names and passwords, and only authorized users can access and control the PLC. At the same time, different operation permissions can be set according to the user’s responsibilities and permissions, such as read-only permissions, read-write permissions, etc., to ensure the security of the system.
Data encryption: Encrypt the transmitted data to prevent the data from being stolen or tampered with during transmission. Encryption protocols such as SSL/TLS are used to encrypt communication data to ensure the confidentiality and integrity of the data.
Remote management platform: used for centralized management of remotely controlled devices and users. It can realize functions such as equipment registration, configuration, monitoring and maintenance, and record and audit user operations, making it convenient to manage and trace the remote control process.
