Interfacing parallel computers to fiber-optic communication links for plant automation

The increasing use of intelligent systems for distributed process control requires computer networks with high real-time capabilities. To meet this demand, high-speed networks have been developed and implemented. FDDI (Fiber Distributed Data Interface), a high speed data network based on an optical fiber technique offers valuable real-time characteristics. The aim of this paper is to evaluate adequate FDDI network parameters to assure the transmission of control data under worst-case conditions. One important feature, that a network for real-time data transfer has to assure, is a deterministic medium access. The evaluation of adequate network parameters requires a deep comprehension of the network behavior under different load conditions. The analysis of such complex distributed systems requires a model that supports the investigation of the logical and dynamical system behavior as well as an analytical evaluation. In this paper an analytical performance analysis and a stochastic Petri net model is used to evaluate the real-time capabilities of an FDDI-based plant automation concept. The performance analysis investigates the possibility of using FDDI as a backbone network and as a plant network. Finally the obtained performance results are summarized and conclusions are presented