Development of performance model for calculation of communication delay in Profibus token passing protocol

In many automated systems such as manufacturing systems and process plants, a fieldbus is a very important component for the exchange of various and sometimes crucial information. Some of the information has a tendency to rapidly lose its value as time elapses after its creation. Such information or data is called real-time data that includes sensor values and control commands. In order to deliver these data in time, the fieldbus network should be tailored to have short delay with respect to the individual time limit of various data. Fine-tuning the network for a given traffic requires knowledge on the relationship between protocol parameters such as timer values and performance measure such as network delay. This paper presents a mathematical performance model to calculate communication delays of the Profibus FMS network when the timer value and the traffic characteristics are given. The results of this model are compared to those from experiments to assess the model's validity. (C) 2003 Elsevier Science B.V. All rights reserved.