Research Of Interface Technology And Communication Protocol Based On Industrial Field-bus And Ethernet

As a leadership of the communication technology in industrial automation domain, Field-bus technology has already been widely used, particularly at the lowest level of the industry control network, namely device level. However, multiplicity and incompatibly of Field-bus standard has hindered its further development, also causes that system and information integration is facing many difficulties.Industrial Ethernet - the application of Ethernet in automatic fields is a solution to the problem above. Industrial Ethernet has already synthesized in information management level, process monitoring level of the enterprise automation systems. It has been successfully implemented that the integration between high level information network and low level control network. After resolving some crucial problems of application, such as real-time communication, credibility of data and so on, Industrial Ethernet can be also applied widely at the lowest level, device level.It is a goal and tendency of control network development that finally realization of the comprehensive seamless information connection and integration from device level to management level. Therefore, the research and exploration of interconnection and deeper fusion between Field-bus and Ethernet has the very strong practical significance and the application value.Both research and discussion are presented in this paper for this topic: Interface technology research, Communication protocol discussion - the improvement of a real-time protocol based on Ethernet.For Interface technology research, it is showed in this paper mainly that the design and implementation of the interface unit between Profibus DP and Ethernet. The hardware structure has been adopted in the interface unit, which includes the singlechip MCU- ATmega128 as a core, supplements SPC3– intelligent communication chip for Profibus DP slave applications and LAN91C111– 10/100Mbps Ethernet controller. Profibus DP slave station interface is composed of ATmega128 and SPC3, and SPC3 has integrated Profibus DP protocol; Ethernet interface is made up by ATmega128 and LAN91C111. It includes the simplified TCP/IP protocol stack; Main function of converting two protocols is completely carried on by ATmega128. Through some tests, it confirmed that interface unit has implemented the basic function of data receiving and sending and conversion of two different protocols. Otherwise, some tests and analysis have been done to show the real-time performance and distance of available communication. It is provided that the interface unit implementation is a reliable and inexpensive solution to the implementation of high level fusion in industrial automation systems.Communication protocol discussion is focused on the possibility of applying Ethernet at the lowest level, device level. It is introduced in this paper that a method to improve the real-time protocol based on Ethernet, referring to Profibus DP field-bus protocol. It has been improved that the original protocol, based upon the...