Fieldbus Protocol Analysis And Network Model

Fieldbus is the lowest level industrial network in the communication hierarchy of factory automation and distributed process control systems. Data generated from field devices are divided into three categories: time-critical, periodic and time-available data.This paper is focus on the bandwidth allocation scheme of Fieldbus networks. Firstly, acyclic bandwidth allocation algorithm provided by Fieldbus draft Standard is modeled, simulated. Moreover, the goal, metric, and methodology of simulation is established. The performance evaluation show that both of the algorithm have their own limitation. Based on the evaluation, a novel acyclic bandwidth allocation algorithm is proposed, modeled, simulated. Through the same evaluation method, the conclusion demonstrate that the performance of the novel algorithm is prior to the old ones. Sencondly, this paper presents an analytic model of bandwidth allocation applicable to fieldbus networks. The bandwidth allocation scheme not only satisfies the real-time transmission requirements of both time-critical and periodic data, but also fully utilizes the bandwidth resources of the fielbus network.Based on the Windows system and on the platform of C++ Builder, we study emphatically on the key technology of how to realize the Fieldbus data-link Protocol. And we find the corresponding solution. Also, we realize that surpport serveral different Fieldbus protocol in our system. With this, we carry out the whole software successfully to meet the end user's demands.The breakthrough of the Internet stimulate much work in the area of fieldbus/Internet connections. As far as the actual implementation of the interconnection is concerned, more widely used approach is that of a gateway. The gateway is the central access point to the fieldbus - typically in a client/server communication style - and alse represents the fieldbus data in a rather abstract way. The paper deals exclusively with these high-level aspects of accessing a fieldbus gateway from an IP-based LAN. The goal is to investigate and compare various protocols that can be used on the LAN side of the gateway. These information will be the guideline for the development direction of our project.