| Computer network (local area network and telnet) as the basis of information technology is one of the most active technological factors at present. Local area network (LAN for short) appeared in the later 1970's which became popular in the 1980's and developed even faster in the 1990's. Nowadays, LAN Tech has been widely used in each field of industry, including the industrial control engineering. Today the companies, as well as the major manufacturers, are actively applying the Ethernet technology to the industrial field. Accordingly, industrial Ethernet is brought forward which is based on commercial Ethernet in technology. Furthermore, it can meet the requirements of industrial field.In the process of tackling the key problem of the industrial Ethernet technology, APC of Zhejiang University, Advanced Process Control, has undertaken lots of works and drafted out an industrial Ethernet standard called EPA for short. This standard's intellectual property rights belong to our nation which is used in the industrial measurement and control system. The committee of EPA has done great effort in order to make the EPA standard become a popular industrial Ethernet communication standard in the world.As a sub-project of EPA, this project focuses on the physical layer of EPA communication standard. Based on the model of the physical layer of 10M Ethernet, this project is a research of the communication mechanism and the cascade principle, in order to prolong the communication distance of EPA. Wiring principle "5-4-3" is widely used in Ethernet because of its practicability and reliability. According to the requirement of the requirement of Standard 802.3, this paper provides an elaborate explanation of the derivative process of the 5-4-3 wiring principle and points out some misunderstanding on it. Then an accurate calculation of wiring is put forward. Finally, by calculation the limit of 5-4-3 principle is breached which is in accordance with the Standard 802.3. More specifically, the cascade series of network wiring is extent to five and the distance of transmission is prolonged to 600m.A signal processor has also been developed for the 10M Ethernet based on the result of the upper research, hoping to shorten the transmission delay and the Interframe gap shrinkage further. Firstly, the paper researched the Ethernet, especially the concept of signal transmission based on lOBaseT. A feasible program was proposed when he got a better understanding of the development task. The whole development is based on the most popular hardware design technology named FPGA and an idea of module designing is introduced. The author had developed the Encode/Decode mechanism of Manchester Code as well as the mechanism for CyclicRedundancy Check (CRC) independently. The hardware circuit can be used into the EPA appropriative chip to improve the communication of PHY; moreover, the processor has been successfully applied for a patent.At present, the signal processor for the 10M Ethernet has been primarily debugged and the signal transmission of the 10M Ethernet has been tested. The result indicates that the processor basically meets the demand of Ethernet, and the error rate is below 0.1%. The mechanism of Manchester Code and the mechanism for CRC have gotten a preliminary application.At the same time, the author also made some research on PoE (Power on Ethernet). This technology can transmit power through the signal cable to the termination of network. The auther made some research on Standard 802.3af, and made clear how PoE works. And the auther developed the Hub with PoE Tech, which is now being protected by patent. Furthermore, based on such application, the data processor can add PoE function in the near future. This will be the next direction of development. |
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