Design Of Modbus Protocol Conversion Module Based On Cortex-M3

Modbus protocol is a kind of widely used in industrial control communication protocol, it’s version of Serial link protocol has long been the dominant in the market, ModbusTCP industrial Ethernet protocol which developed later realizes Ethernet communications for equipment. The traditional way of Modbus serial link communication does not support Ethernet communication, it’s communication distance is limited and communication rate is low. For this reason, this thesis using Cortex-M3micro processor combined with RS232and Ethernet communication establishs a Modbus protocol conversion module. The module can communicate with various devices supporting Modbus protocol through the EtherNet and RS232communication methods. The system succeed in connecting Modbus devices to Ethernet, using the protocol conversion function of the module, we can implement networked remote control to Modbus serial devices through the Ethernet.The first two chapters of the thesis put forward the overall design scheme and research method first according to the functional requirements of the system, then make a general introduction to the communication specification and application technology of Modbus protocol. The third chapter describes each function module’s design process and principle diagrams of hardware part in detail. The fourth chapter introduces the software system program design idea, including the underlying drivers of each function module and function realization, and the application layer program design based on uIP protocol stack. The fifth chapter introduces on-line debugging lpprocess of the system. The completion of this project is summarized at last.According to reality testing, the operation of the system is stable and reliable, which proves the design is feasible and achieves the expected design requirements.