The Design of a Novel Modbus TCP/RTU Gateway for High Reliable Communication
Honglin Zhou, Junlin Song, Xiaomin Pu · 2022
High reliable control is mandatory in many industrial scenarios, such as excitation control, protection relays, etc. The controllers in these scenarios are typically required to be able to access redundant Ethernet with dual host redundancy. However, for cost-effective embedded real-time controllers, this requirement is extremely difficult due to their limited hardware resources. This paper proposes a novel Modbus TCP/RTU gateway for high reliable communication. With this gateway, all controllers can act as the master to start communication with all other devices on the virtual Modbus RTU bus without worrying about dual master conflict. While the controller is the master, it can also be addressed and accessed by other controllers or standard equipment as a slave, that is, it can realize full duplex communication. For any controller, all data frames are orderly and consistent, and there is no need to worry about the disorder of packet caused by the network uncertainty. All connections exist simultaneously yet independently, and the failure of one connection will not affect others at all. Connections can be self-recovered. Once the fault is removed, the broken connection can be automatically re-established. First, the typical topology and requirements for high reliable Modbus TCP Communication are introduced. And then, the architecture of the gateway design is given. After that, the addressing system and data conversion of the gateway is proposed. Finally, the prototype gateway is implemented and verified by experiments.