Application of dual redundant industrial Ethernet technology in DCS system
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Overview of industrial Ethernet redundancy technology
Due to the harsh industrial environment, the industrial control network has higher reliability requirements than the commercial network, which leads to the redundancy technology of industrial Ethernet. Ethernet redundancy technology in industrial automation includes: power supply redundancy, media redundancy, network node redundancy and so on.
The basic redundancy requirement of the control system is that every part of the communication network can be connected to a backup power supply in the event of a power failure, and in the event of a power failure, the backup power supply begins to take over and send a power failure alert to the management via E-mail or relay output. Medium redundancy can form an alternate path at some network nodes, which is the industrial Ethernet ring network technology advocated by TSC.
Network node redundancy is to make the switch connected to the device to build a dual network node, and both network nodes must be connected to the dual-boot controller. When a disaster occurs, ensure that the controller is connected to the terminal. Connect the two Ethernet interfaces to the two redundant switches and select the stable one as the primary path to ensure normal system running. Network redundancy is the construction of a network in which all devices have redundant functions. A fully redundant system consists of redundant switches, redundant communication ports, and a pair of redundant devices. All Ethernet devices and workstations must be connected to two separate network loops. Full system redundancy results in a reliable network with minimal data loss and fast redundancy times.
Second, the implementation of double redundant industrial Ethernet in DCS
In order to construct 10M / 100M adaptive dual redundancy industrial field Ethernet communication network, it is necessary to select the matching network type and carry out reasonable redundancy configuration.
First of all, the selection of industrial Ethernet type must consider the existing control platform and the characteristics of various networks. Because the series PLC used in the control platform has an industrial Ethernet communication module based on Modbus/TCP protocol, and Modbus/TCP industrial Ethernet has obvious advantages in considering the initial investment and making full use of existing resources because of its simple and efficient characteristics. Therefore, 10M / 100M adaptive industrial Ethernet based on Modbus/TCP protocol is used in the system.
Secondly, in order to ensure the reliability of the communication network, reasonable redundancy of the control network equipment should be carried out according to the actual situation of the field. ① Power reliability: To ensure the normal power supply of network devices, all switches are powered by the UPS. (2) Device redundancy: Configure two TSC Carat5508 series switches in each, and each switch adopts redundant power configuration, two communication Ethernet cards are configured on each PLC, and two Ethernet cards are configured in each monitoring computer. (3) Communication media redundancy: The industrial redundancy ring network protocol is used to make the communication between each device have a redundant path. Through the above redundancy technology, the double redundant star 10M / 100M adaptive industrial Ethernet based on Modbus/TCP protocol is finally realized.