Design and analysis of packet-switched networks for control systems

This paper presents a methodology for analyzing and designing a packet-switched computer network for application to complex control systems. The focus is on generating the high-level control network that interconnects input-output controllers with devices for monitoring and analysis and with high-level controllers such as supervisory PLCs. Part of the development given in this paper can also be applied to the device-level network (Fieldbus) that interconnects input-output controllers with sensors, actuators, and other devices in the system being controlled. A procedure is given for generating a network design with a hierarchical hub topology having full redundancy. Then in terms of a graph model of the network, an algorithm is presented for computing the information flow rates in the network design, which can then be used for capacity planning and estimating the delay times through the network.