Research Of Protocol Conversion Module Based On DeviceNet-Modbus

DeviceNet is an open device-level fieldbus network based on CAN technology developedby Rockwell. Used the analysis method of object-oriented, this protocol has been more andmore widely used in the industry,and has become a national standard. Modbus communicationprotocol is a communication language which was first used in the electronic controller.Through the Modbus communication protocol, Communication between the controller andthe controller, the controller and other communication devices can be achieved. At present,many industrial field devices with RS-232,RS-485 or RS-422 serial communication hardwareinterface,using a simple custom communication protocol or Modbus protocol to achievecommunication, but most of them do not have as DeviceNet slave communication function.Therefore,research and design a device which convert Modbus protocol into DeviceNetprotocol has important research significance and application value. So, a protocol conversionmodule is designed in the paper which made instruments with Modbus interfacecommunicating to DeviceNet fieldbus.The main content is introduced as following.1、At the beginning of this paper, the condition of the fieldbus development is introduced,as well as the research content and the signification. Then use the DeviceNet object-orientedanalysis, comprehensive Analysis of the DeviceNet bus protocol packet types, object modeland the communication mode of choice.Finally, research the Modbus communication protocoltechnology, including protocols interface technology and message formats.2、In-depth study achieve the two protocol stacks of the key issue which used amicro-controller to implement DeviceNet and Modbus communication technology,and thendesigned the overall program.On this basis, the papers give effective hardware and softwaresolutions. Implemented in the hardware design of microcontroller and CAN controller chip asthe core of the DeviceNet bus interface module circuit and the microcontroller,RS485transceiver core Modbus interface module circuit.C51 language used in the softwareimplementation of the Modbus communication protocol procedures,predefined master / slaveprotocol to connect program from the software modules including packet transceiver module,the basic object identifies the object module, explicit message processing module,polling I / Opacket processing module. Through hardware and software implementation, completed databetween different networks for reliable communication.3、According to DeviceNet and Modbus slave testing and other aspects of technical andfunctional requirements,the test program conducted in-depth analysis and argument,to build aDeviceNet Slave experimental test platform,to connect devices with a Modbus interface toexperimental tests.Detailed analysis of the experimental results, the paper confirmed thecorrectness of the proposed design solutions to achieve a Modbus device and DeviceNetfieldbus communications.