| Fieldbus has been used in the field of modern industrial control widely becauseof its open, operability, real-time characteristics. Using fieldbus is an important wayfor the informatization of enterprises. Due to the historical reason and the differenceof the application area, there are a varity of Fieldbus standards which coexist in thearea of the insudtrial. The fieldbuses with different protocol can not communicatewith each other. The diversity of the Fieldbus standard increases the difficulty offieldbus technology upgrade based on the original devices and hinders the informationexchange between different fieldbuses. This situation is not conductive to thedevelopment of enterprise informatization. For these reasons, the research ofinterconnection between fieldbuses with different standard is very urgent and haspractical significance.PROFIBUS-DP, CAN bus, Ethernet and RS232 were used as the research objectsin this dissertation. The protocol conversion method based on protocol frameconversion has been proposed by analyzing their protocols and communicaton models.Based on this method, a multi-protocol fieldbus conversion gateway has beendesigned. The other fieldbus devices were connected to the PROFIBUS-DP as slavesthrough the conversion gateway. Therefore, the development of the protocolconversion gateway was based on the PRFIBUS-DP slave.First, the dissertation introduced the technological features of these fieldbuses,and focued on the research and analysis of the working way and protocol framestructure of the PROFIBUS-DP, CAN, Ethernet and RS232. Then, the hardware of theconversion gateway was designed according to the functions of the gateway. In orderto simplify the design of the hardware and improve the performance of the gateway,the ARM9-based processor was adopted. At same time, protocol chips were used todesign the fieldbus communication interfaces. Last, protocol conversion software wasdesigned based on the protocol frame design and the research of protocol conversionpreviously. The dissertation elaborated the design objective and framework of thesoftware. The features of Linux and the device driver developing under Linux wereintroduced. The dissertation analysised the implementation of the protocol conversionand the scheduling and communication of tasks related. Under the circumstance of Laboratory, virtual devices were used to simulate theapplication of the multi-protocol conversion gateway. The results showed that theCAN device and RS232 device can communicate with PROFIBUS-DP mater statationnormally. The PROFIBUS-DP mater statation can send data to the Ethernet. |
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