DISTRIBUTED SYSTEMS EMPLOYING MODERN COMMUNICATION STANDARDS IN ACCESS CONTROL AND SCADA

The paper explores the concept of distributed processing within both access control and supervisory control and data acquistion (SCADA) systems. The emergence of industry standards in the context of inter-process communications in systems employing distributed processing is also discussed. Particular attention is given to the subject of the proposed FIELDBUS standard and some of its implementation trade-offs. The definition of a suitable application protocol is discussed together with the interface requirements of such a system. A rationale is proposed to allow the difficulties presented by a proliferation of standards to be addressed by intending suppliers of these types of systems. Examples are given of some commercially available systems which utilise this technology in their implementation. In particular a security access control system and a distributed instrumentation system are discussed and the use of a FIELDBUS within these products is evaluated.