The Development Of PROFIBUS-PA Communication Interface And The Research Of Key Technology

Intelligent fieldbus control system has brought tremendous changes for industrial automation technology. Fieldbus can realize the distributed digital control and field communications from field devices to the monitor of workshop level,which is called factory's automation and devices'intelligence. In the process control areas, PROFIBUS-PA is one number of PROFIBUS,and it has lots of advantages which can be used in an intrinsically safe area.Under a deep research of PROFIBUS-PA technology,we design a PA communication interface for the differential pressure transmitter,thus it can be used in the process control areas.Because the exploitation of PA products just started, this paper's design can fill the gaps of PROFIBUS-PA in the fields of product development in China,it also has a great improvment both in automatic control technology and fieldbus instruments .In this paper, we briefly introduce PROFIBUS communication protocol firstly,then we take a deep research on IEC61158 transmission technology,communication protocol of DPV1 and the protocol rules of ASIC chip DPC31 and modem chip SIM1-2 from Siemens.With a fullly understanding of PROFIBUS technology and its corresponding communication protocol, this paper design a scheme of PROFIBUS-PA interface for intelligent slaves. As to the hardware design,we adopt the method of MCU+DPC31+SIM1-2; as to the software design, at the basement of the the modular software design and program flow charts, we use V1SL in the DP/PA development kit as the driving program of DPC31,so users only need to operate its maco interface and change parameters of their own according to their actual needs.Thus we can change the datas between the master and the slaves using IO maco interface and realize the fuction of PA communication. Using this interface,differential pressure transmitter is used as a slave to access to PROFIBUS system through PROFIBUS-PA communication interface,so it achieve the intelligent control of field devices.In this paper, the slave interface module have following features: differential pressure transmitter can access to DP network through DP/PA coupler, this ensure the realization of DPV0 and DPV1 communication.Finally, according to the actual application conditions and the existing experimental environment, this paper build an experimental test platform for system testing of the interface module. The results show that the differential pressure transmitter with this interface can fulfill acyclic data communication with main station. The master class has a better reliability and versatility, which can be applied to all devices.