Users Guide Instruction Manual

IB-23C650
POSITION PROPORTIONING CONTROL
POSITIONING PROPORTIONING CONTROL
DESCRIPTION
Positioning proportioning control permits PID control to be used in applications
where the control element is an on/off positioning device such as a motorized
valve. The controller output is provided by two SPDT relays. One relay
actuates opening of the valve, and the other closing of the valve. Positioning
proportioning control requires the option board to receive the valve position
feedback.
The calculated output generated by the control algorithm goes to a valve
motor driver as shown in Figure 31. The driver operates the output relays and
receives stem position feedback via input 2. An increase in calculated output
opens the valve by actuating the opening relay, and decreasing the output
closes the valve by actuating the closing relay. The position feedback gives
the controller a measure of valve stem position so that valve position in
percent full stem travel corresponds to percent calculated output.
Figure 31. Output Driver Stage of Position Proportioning Controller
Slidewire, mA, mV,
or Volt Input
(Valve Stem
Position Feedback)
Valve
Calibration
S-1107-266
Valve Motor
Driver
Output
Calculated
Output
• Valve
Deadband
Relay Output
(Open)
Relay Output
(Close)
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