A deterministic communication protocol for distributed real-time systems

The authors describe an efficient communication protocol for transmitting time-constrained messages in a time-division multiple-access local area network. The proposed protocol differs from traditional protocols in this category in that it uses the bandwidth of the medium more effectively by explicitly passing the mastership between stations. In the present protocol, the drawback inherent to fixed-master protocols, viz., imposing a star topology in a multiple-access environment. is resolved, resulting in shorter response times. The proposed protocol provides for the fair passing of the mastership between stations, thus guaranteeing the same response times for all stations. The mastership-passing protocol has been implemented and extensively tested in a 2.5 Mb/s real-time network