Study on field control locations for Foundation Fieldbus-based cascade control loop

This paper focuses on implementing cascade control in the field using Foundation Fieldbus technology. The key consideration is the assignment of master and slave PID block locations in Fieldbus devices for minimizing network traffic without negative impact on an ability to control the process. A plant model using multi-vendor Fieldbus devices for level-to-flow cascade control is described as an illustrative case study. This paper examines calculated macrocycle timing schedules produced by the DeltaV system for six possible field control locations of the PID blocks. Experimental results obtained from the preferred field control location with minimum number of scheduled data transmissions over the network are also included.