Design And Implementation Of Profibus-Based Master Station Of DCS

In this paper, an automatic control system based on PROFIBUS fieldbus technology has been put forward as the original system's slow communication, non-redundant communication networks, slow dual controller switching speed, weak reliability, stability and so on issues. Current system have many advantages: high communication rate, the good reliability of the underlying communications, dual redundant communication networks, a fast dual switch, good stability, strong real-time performance, and its openness, then it greatly improve the performance of the original system in all aspects. Above all, the system will have significant commercial value.First in this paper, some content relevant with PROFIBUS bus protocol is introduced: PROFIBUS-DP protocol analysis and the principle of master and slave communication. Then the master station's overall design is described in three parts: the general hardware scheme of the system, the overall module structure and the software design solution of PROFIBUS master station. Later the PROFIBUS master's detailed software design is presented in three specific modules: Communication equipment and Host computer interface design, PROFIBUS master's communication software design and PROFIBUS master's fault-tolerant design.In the following section, the configuration, access mechniasm, handshake and data interface of DPM (Dual Port Memory) are focused on to introduce the implement interface of the Communication equipment and Host computer. Then the detailed implementation of the PROFIBUS master's communication software is introduced: application task's implement of rcX (realTime communication System for netX) operating system, Master and Slave station and PROFIBUS bus parameter configuration, Master and Slave communication process and Single Master and Multi-Slave communication process, diagnosis, alarm functionality and so on. At the end of the section, the three specific implementation module: dual redundancy PROFIBUS network interface, dual redundant master station and dual redundant heartbeat line are constituted of PROFIBUS master's fault-tolerant module. In the final chapter, testing work from the perspective of software on the hardware of the master station, and testing PROFIBUS master's software functionality based on the design and implementation in the former two chapters has been done. And the test results show good integrity, accuracy and stability of system functionality. Many aspects of the current system has been greatly improved than the original system, such as communication speed, dual master switching speed, dual redundancy network and reliability, stability and real-time performance.The current developed system will have broad market prospects.