Honeywell VCR DCP200 User Manual

DCP200 Profile Controller & Recorder - Product Manual

Page 74

Manual Tuning

51-52-25-150, Issue 1 – April 2009

This technique balances the need to reach setpoint quickly, with the wish to limit setpoint
overshoot at start-up or during process changes. It determines values for the Primary 
Proportional Band and the Integral and Derivative time constants that allow the PID control
algorithm to give acceptable results in most applications that use a single control device.

1. Check that the Setpoint Upper Limit and Setpoint Lower Limit are set to safe levels for 

your process. Adjust if required.

2. Set the Setpoint to the normal operating value for the process (or to a lower value if 

overshoots beyond this value might cause damage).

3. Select On-Off control (i.e. set the Primary Proportional Band to zero).

4. Switch on the process. The process variable will oscillate about the setpoint. Record the 

Peak-to-Peak variation (P) of the first cycle (i.e. the difference between the highest value 
of the first overshoot and the lowest value of the first undershoot), and the time period of 
the oscillation (T) in minutes. See the example diagram below - Manually Tuning PID.

5. Calculate the PID control parameters using the formula below. P.Pb is the Primary 

Proportional Band, Int.T is the Integral Time Constant, and Der.T is the Derivative Time 
Constant. The Input Span is the difference between Scale Range Lower Limit and Scale 
Range Upper Limit:

Figure 47.

Manually Tuning PID