| As one of the open fieldbus communication technology, DeviceNet has been used more and more widely in the industrial field. RS-485 is serial communication technology in traditional industrial control. RS-485 serial interface is on lots of field instruments. But they could not communicate as slave on DeviceNet. By using the DeviceNet fieldbus, eliminating these instruments were not reasonable. For resolving this problem, a protocol conversion module is designed in the paper which made instruments with RS-485 interface communicating to DeviceNet fieldbus. The main content is introduced as following.At the beginning of this paper the condition of the fieldbus development is introduced, as well as the research content and the signification. Then serial communication technology including of common serial interface standard and application is illustrated in details. And DeviceNet protocol is also introduced.Including of single chip microcomputer minimal system, power source circuit, serial interface circuit, DeviceNet fieldbus circuit and memory unit, with the core of single chip microcomputer AT89S52 hardware is designed and introduced in details. Under the Delphi programming circumstances, configuration software of the protocol conversion module based on MSComm is designed. By parameters configuration, communication is carried out under different net condition. The hardware function of the module is carried out with software which is designed by using C program language. And communication requisition under poll data trigger mode inside the module is achieved.Experimental test is carried out by building the test platform and using RS-485 industrial instrument. The test results are analyzed, which shows that the correctness of the design scheme is verified. The communication between traditional RS-485 industrial instrument and DeviceNet fieldbus is carried out. The research provides good thought for connection of different fieldbus as well as fieldbus and low level industrial instrument. |
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