Distributed data communication networks for real-time process control

The paper deals with the performance analysis of network access protocols for distributed data communication and control systems (DDCCS) in chemical and processing plants. The selection of an appropriate daia highway protocol is an important step in the DDCCS network design for large-scale processes because the real-time feedback control loops are subject to time-varying delays resulting from data latencies and possible mis-synchronism between system components. SAE token ring, SAE linear token bus, and MIL-STD-1553B protocols have been analyzed in view of the DDCCS network design requirements. The results of closed loop control system simulations are presented to demonstrate how data latency generated by the network access protocols could degrade th rlvnamic ne.rfnrmance of the controlled process.