The Research Of Belt Conveyor Control System Based On PLC Network Communications

As the integrated product of computer technology, communication technology, instrument technology, and control technology, Fieldbus is one of the focuses of the current technical development in automatic field. PROFIBUS, as one of the international specifications of fieldbus, is provided with advantage of internationalization, opening, high agility and high reliability, has been used extensively in automatization of processing, automatization of machining and automatization of building.In this paper the protocols, properties and advantages of PROFIBUS fieldbus are researched. The paper mainly introduces the property, the function and the communication model of PROFIBUS-DP. On the basis of research on standard of PROFIBUS, one kind of Master-Slaver structure control system based on PROFIBUS-DP with SIEMENS S7-300 series PLC is researched and designed.Based on the analysis on large power belt conveyor, and according to the specific requirements of belt conveyor, this paper indicates that the frequency converter could be used to realize soft-start procedure and speed adjustment of belt conveyor. The paper focuses on two problems of adopting frequency converter for belt conveyor: Firstly, speed regulation includes soft-start problem. Based on analysis on dynamic mathematical models of belt conveyor, the paper studies the best soft-start method and presents a perfect soft start curve;Secondly, the paper studies reason what causes unbalance of power, and develops the method how to adjust balance of power by frequency converter...