The Communication of Control and Maintenance Data over a Single Digital Automation Network, using Intelligent Sensors and Distributed Processing

摘要

Digital communications networks based upon the fieldbus concept are now the norm for factory-widernautomation systems. Such systems are employed extensively in industry for the real time control of plant,rnyet the hierarchical communications protocols at the heart of many of these systems permit them to bernused for much more than this. In principle, it is quite possible that all control, monitoring and informationrnfunctions be performed using a single network. The advantages of such integration are many fold, fromrnhardware economics through reliability of operation to the exploitation of control information forrnmaintenance purposes. This paper reports work presently being performed with WorldFIP and Alstom torndevelop a demonstrator integrated network system which combines the functions of real time plantrncontrol, machinery condition monitoring and management information services within a single networkrnsystem.rnOf fundamental importance to the functioning of an integrated network system is the fact that real timerncontrol must not be disrupted by the operations of the condition monitoring or management informationrnservices. This functionality can be guaranteed by the appropriate use of the established fieldbus messagernhierarchy. Furthermore, this protocol readily permits the communication of non-time-critical conditionrnmonitoring and management information data in the portion of the bandwidth which may be unused byrncontrol data at any instance in time. To function effectively, the data exchange required for the conditionrnmonitoring function must be minimised, and for this reason it is necessary to employ a distributedrnprocessing approach, with intelligent condition monitoring sensors, which function on request from arncentral condition monitoring controller.rnThis paper commences with an overview of fieldbus systems and the way in which they are currentlyrnapplied. The use of both machinery condition monitoring and control data is then discussed and arnmethodology by which the integration of these functions can be achieved is presented. The paper thenrnexplores the functioning of intelligent sensors within this context, and their operation with a centralisedrnmonitoring controller. Finally the paper summarises the capability of a developed demonstrator systemrnand shows a range of operational results.