Implementation of bandwidth allocation scheme in the cyclic-service fieldbus networks

This paper presents an implementation method of bandwidth allocation scheme on Profibus which is operated on the basis of cyclic-service discipline. In order to implement bandwidth allocation scheme on Profibus, this study supplements the following functions on the FDL (Fieldbus Datalink Layer) protocol: (i) separation of medium bandwidth into periodic and time-available intervals, (ii) synchronization of node timers over a local link. In order to examine the validity of bandwidth allocation scheme, this paper develops an experimental model of a network system. The results obtained from the experimental model show that the bandwidth allocation scheme satisfies the performance requirement of time-critical, periodic and time-available traffic.