The Research And Design Of DeviceNet-Modbus Fieldbus Protocol Converter Of Circuit Breaker

Developing communicating-capable low-voltage electricial apparatus adapted to with multiple kinds of fieldbus is becoming an important trend. The circuit breakers developed newly of some foreign big company can connect with some fieldbus network ;However, nearly all the Communication interface of the circuit breakers that some domestic companies developed newly are based on the traditional RS-232 or RS-485 hardware interface, and use self-defining communication protocol or Modbus protocol to realize the communication function . DeviceNet fieldbus has been adopted by the international fieldbus standard IEC62026, and also authorized as fieldbus standard of Chinese electricial apparatus industry and fieldbus standard of China. Modbus fieldbus has been applied widely for its simple protocol and little investment, and in fact it has become the industry standard.Aiming at present situation above, a DeviceNet-Modbus fieldbs protocol converter is reserched and designed through the study of CAN bus technique ,DeviceNet bus technique and Modbus bus technique. The 16-bit microprocessor M301N2F8 with built-in CAN control module is adopted in the hardware circuit of the converter, using its CAN module to realize the physical layer and media access control layer of DeviceNet, and using its UART and RS-485 transceiver SN65LBC184 to realize physical layer function of Modbus comunication. Concerning the software system , C languager is used to program to realize the transmit/receive Message of DeviceNet, transmit/receive Message of Modbus and the conversion between DeviceNet messages and Mobus message.Though it is a kind of special protocol converter of the circuit breaker , it has used the most protocol of DeviceNet, so it has good reference function for developing DeviceNet-Modbus protocol converter of other equipments and other DeviceNet products further. The application of the converter will expand the function of circuit breaker , realize the intelligentizing and networking of the circuit breaker and make networking of circuit breaker more flexible with economy, adaptive to different fieldbuses.