Design And Research Of The Communication Interface Of The Intelligent Controller Based On Profibus

Profibus-DP is the bus technology absolutely leading market share, which is used in equipment grade control system and dispersed mode of I/O communication. Presently, internal application and research on Profibus-DP gives priority to foreign complete equipments, but with the less communication interface developed independently. In order to promote the intelligent process of the instruments field in our country, it is especially important to develop Profibus-DP communication interface for instruments and electric apparatuses. According to the application and development of the field bus, in this paper an intelligent communication module based on Profibus-DP is proposed.The content of this paper mainly includes the following aspects:Firstly, after introducing the survey and history of field bus technology, the development and potential application of Profibus-DP intelligent slave are discussed; the limitations of Profibus-DP technology study and application in our country and the research significance of the proposed technology are pointed out.Secondly, the basic theory of Profibus-DP Field bus is studied,after comparing with several realization of the Profibus-DP`s programs, the proposal which based on the module of ASIC chips and MCU to develop the communication interface of Profibus-DP slave station are given.Thirdly, the hardware circuit, which is based on SPC3 chip, including the memory distribution circuit, ASIC interface circuit, MCU interface circuit and RS485 interface circuit is researched and designed, especially, accoreding to the feature of industrial application, the general RS485 connection is improved to enhance the system stability and anti-interference ability. The state machine of the slave station and the structure of the buffer zone in Profibus-DP are analysed,then the software's design ideas is figured, and the system main program files , the interrupt module , the electronic device data files of the software module and implementation is also given.Fourthly, The CP5611, as a master combining with the module of slave interface , the minimum system in the module of signal master and signal slave based on field bus of Profibus-DP is formed , the communication function test of the designed slave interface module has completed ,the result of this test is given and analyzed.The final test result indicates that the intelligence module realizes the process of communication based on Profibus-DP, the general intelligence instruments and the attributed I/O equipments which accord with the standard Profibus protocol can run well in this module. The system is stable and reliable and achieves the design goal.