Performance Evaluation Of Profibus Based On Discrete Time Queue

FCS (Fieldbus control system) is a new generation of control system. It represents a developing direction that digital devices, network devices, control functions, device management, which are used in local machines. FCS is going to be the mainstream of automatic technology in the future due to its advanced character, practicability, reliability and openness. FCS makes the information of computer control system be all over the world: include equipment, workshop, plant, factory, enterprise and the market. The auto-control system changes to distributing structure step by step.The PROFIBUS is a well-known and widely used fieldbus. The analysis of the PROFIBUS performance is helpful for the system design and system optimization. In order to analyze and evaluate the performance of PROFIBUS, the following points are studied:Firstly, after the detailed introduction of PROFIBUS protocol, the process of token-passing and MAC (media access control) are deeply analyzed. A universal polling model is built for Token-Passing in PROFIBUS based on queue theory, and some performance standard of PROFIBUS is given.Secondly, in order to analyze PROFIBUS, two queuing models are built base on continuous time and discrete time queue theory with vacation. Two discrete time queuing models, DMAP/M/1 and DMAP/D/1, are studied. In different message mode, the model is different. The method of model building and the performance analyzing of PROFIBUS is given in this paper. The performance aspects are studied theoretically, such as: delay of messages, network utilization and message finish rate. Simulation results are given in each chapter in order to understand the queuing model facilely.