Perform Common Process Loop Control Algorithms

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Perform Common Process Loop Control Algorithms Using the PIDE Instruction Introduction This white paper discusses how to use the features inherent in the Enhanced PIDE instruction in the RSLogix 5000 Function Block Diagram (FBD) editor to Perform Common Process loop Control Algorithms such as: adaptive gains cascade Control ratio Control multiloop selection split-range time-proportioning Although this paper focuses on the PIDE instruction, be aware that the FBD editor supports many other Process Control instructions. Other instructions provide capabilities such as flow totalization, ramp/soak temperature profiles, motor operated valve Control , and two- or three-state device Control for devices such as pumps and solenoid valves.

A velocity form PID algorithm provides a clear advantage for these types of control schemes. Since the previous output of the loop is available in the CVn-1 term, it is a simple matter of wiring the output actually sent to the final control element into the CVn-1 term of each loop. The two loops will therefore

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