The Technical Research And The Development For The Communication Interface Of PROFIBUS

The fieldbus has become an hot spot of the development of automatic technique because its many strong points for example, its adoption will make the structure of control system become simple, make the erecting expenses of control system decrease, make the system maintenance become easy, and make the user can choose different brand field devices produced by different manufactures to realize the integrated system. PROFIBUS has already become one of the openly international standards and been used widely in the whole world, which not only provides the new market opportunity, but puts forward serious challenges to the domestic field devices and instruments. To enter the international market and be conveniently connected to the standard PROFIBUS net, domestic fieldbus products must have PROFIBUS communication interface, therefore, it is urgent to develop the PROFIBUS interface for the domestic fieldbus equipments in the automatic field.The PROFIBUS includes the PROFIBUS-DP, PROFIBUS-PA and PROFIBUS-FMS. PROFIBUS-DP is a kind of optimized communication connection with high speed and cheap expenses, and it is used to realize the communication of the automatic control system to the distributed I/O equipments.This paper analyzes the PROFIBUS in theory and emphasizes the protocol and message structure of the PROFIBUS-DP, based on which this paper puts forward two development proposals for the PROFIBUS-DP intelligent slave station's communication interface. One is to develop the interface with the SPC3, the other is with the software that realizes the protocol of the data-link layer.This paper mainly describes the hardware composition and software program for the first development. That is the development for the PROFIBUS-DP intelligent slave station's communication interface with the SPC3 produced by SIEMENS. The key time sections of the PROFIBUS-DP protocol are implemented by a protocol chip named SPC3, and other sections are executed by the 80C32.Finally, this paper discusses the second development for the PROFIBUS-DP intelligent slave station's communication interface, with which the PROFIBUS-DP protocols aren't implemented by the chip SPC3, but by the software. The communication with the master station can be realized through the interface UART of the microprocessor.