A Simulation Study on the Performance Analysis of the Data Link Layer of IEC/ISA Fieldbus

Fieldbus provides real-time data communication among field devices in the process control and fac tory automation systems. IEC and ISA recently approved the fieldbus standard for use in indus trial control systems. The data link layer of IEC/ ISA fieldbus provides token-passing and schedul ing services for data transmission. This paper ana lyzes the performance characteristics of the IEC/ ISA fieldbus, especially the capabilities of the real- time data transmission and priority mechanism. In this study, a discrete-event simulation model of the data link layer of IEC/ISA fieldbus is developed. Using the simulation model, this study identifies the network parameters that influence the perfor mance of the data link layer, and investigates the delay performance with respect to the change of the network parameters. Based on the simulation analy sis, this study draws essential conclusions that should be considered in the network system design and operation of IEC/ISA fieldbus.