Networked control systems-plant interfacing issues

The paper looks at the problems associated with designing LANs that incorporate direct (`passive node´) interfacing to controlling elements. Two general schemes based on the token-bus principle suitable for use in such fast real-time applications are described. Their performances are evaluated (using simulation studies) in terms of system responsiveness and fault tolerance within the context of distributed real-time systems. It is finally highlighted that no single scheme provides a global networking solution for distributed control applications. As a result, in the design of high speed real-time LANs, the organisation of passive nodes is largely dictated by the nature of specific application requirements