Efficiency issues of polling protocols for Fieldbus networks

This paper considers polling protocols for industrial local area networks. Such networks are employed in process control and manufacturing. They operate in the presence of hard real-time constraints. The authors present two protocols for these networks and discuss implementation issues related to their efficiency and jitter. The efficiency indicates how best the available network bandwidth can be utilized and the jitter indicates the uncertainty in the execution of the protocol. Two possible implementation methods, namely sequential and superposed, are discussed. The paper also presents implementation results.