The Research And Design Of Embedded Multi-network Protocol Converter

As a new generation of control system,fieldbus has advantages of higher stability and better real-time,widely used in the industrial field, but it has multiple standards at the same time. In this way, the communication between multiple bus will give users a great deal of inconvenience, and communication rate of the fieldbus generally is ower. Ethernet meets high-speed stability requirements of the industrial control network, Its application fundamentals is very broad. When used in the underlying device,it still exist such as real-time and security problems. The research priority of the industrial areas is to realize enterprise management and control system integration, and the most effective measure is to promote the Ethernet into the industrial field bus with complementary advantages of the technology.The thesis design a multi-protocol converter on the basis of the research and analysis of industrial Etherne and field bus,.It intergrated a variety of fieldbus in a system to exchange protocol data with Ethernet separately, solving the connection between the equipment layer and the information layer of the industrial network.The design use the field bus include CAN and PROFIBUS_DP bus, serial interface RS232bus. The thesis discussed the design scheme and the realization method of the converter in detail from the perspective of hardware and software.After reasearched protocol structure and the communication access method of the CAN and PROFIBUS_DP bus, the thesis is centred on ARM7processor LPC2378,setting CAN interface, PROFIBUS_DP interface, RS232interface and Ethernet interface buffers in its RAM, the main controller controlling the interface data buffer exchange data, realize each interface data and Ethernet data conversion.Considering the versatility and compatibility of the design for the hardware platform, the hardware is modular in design, a total of5modules including Master control module,ethernet module, CAN module, PROFIBUS_DP module and serial module. The host controller uses high-performance processor chip LPC2378, it integrating a10MbPs/100MbPs Ethernet controller, two CAN2.0specification CAN controller, and four universal serial interface. Physical layer (PHY) chip of Ethernet module used DM9161A;CAN isolated transceivers used the CTM8251AT; the PROFIBUS_DP module used VPC3+C protocol chip which package complete DP slave protocol;the serial module used the MAX3232chip as serial level conversion.Software design is based on the developed hardware platform.Firstly, transplant real-time operating system μC/OS-II to processor LPC2378,to make the system be multi-task scheduling.Secondly, transplant ZLG/IP protocol stack to the μC/OS-II, to achieve network functions. At last,write the device driver for each interface module and design the architecture of protocol conversion process.