Performance issues in low-cost communications for distributed transducer systems used for monitoring and control

Abstract

Transducers with in-built microprocessors will gain in popularity over the next few years. As they do so, they will become a familiar component in the large and complex control systems in process and manufacturing environments. This paper discusses the use of Local Area Networks' (LANs), digital communication techniques in a system that can provide an efficient and flexible interconnect for a number of transducers involved in monitoring and control. Justification of the use of a bus type system, as opposed to other LAN topologies, is based on it providing a minimal interconnect distance and greatest interconnect flexibility. Simulations have been performed to determine the loading/delay characteristics of two types of bus protocol when implemented on single chip microprocessors. These delays are then used in the simulation of a control loop to determine their effect on the output error of a simple first order process. The investigation of these responses will eventually lead to system design criteria for loading/control response objectives.