Communication schedule optimization of cascade control using foundation fieldbus

This paper presents a technique to optimize the communication schedules generated for synchronization of Foundation Fieldbus H1 devices in cascade control loop. A level-to-flow cascade control operated by the Harmonas-DEO host system is examined as an illustrative case study. Major objectives of the optimization are not only to minimize the latency of the control loop but also to maximize the availability of the network bandwidth. The proposed technique can be applied for H1 segment macrocycle schedules performing the control functions in both of the host controller and the field devices. Three examples for optimizing communication schedules generated from different control block assignments are described. The validation of the optimization methods can be determined by using two metrics: control loop latency improvement and publication gap availability improvement. Experimental results confirm that the proposed technique works effectively to operate the studied H1 segment for cascade control without any problems.