The testing of Group3 controllers - the CNA and DNA - have a built-in PID algorithm, that allows them to perform local closed loop control. A controller, combined with a Group3 analog Hall probe forms a compact, inexpensive way to implement closed loop magnet control. The computer only needs to send the desired field value - the controller will drive the power supply to steadily maintain that field setting. The magnet and power supply becomes a simple "set and forget" system, relieving the control computer and the communications network of any ongoing control or supervision.

Two controller modules are offered - the CNA is part of the Group3 Control system, and communicates via fiber optic cables to a Group3 card in the computer. The DNA communicates on a DeviceNet network, the standard for industrial control.

For more information please visit http://en.wikipedia.org/wiki/PID_controller

Block Diagram of a PID Controller

(Source http://en.wikipedia.org/wiki/Image:Pid-
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