Trane Tracer MP501 Installation, Operation And Maintenance Manual page 42

PID Control
Changing the Sampling Frequency
The major cause of actuator cycling is time lags in the system.
Note: If a 10% change in PID output requires two minutes to affect the process variable, it does no
The integral contribution will build up before any significant change in error can be measured. A
sampling frequency of 30 to 60 seconds would work much better in this situation. In other words,
to fix a cycling system, slow down the loop! Refer to the section,
Changing the Gains
Be careful when changing PID gains.
Note: Never change gains unless the effects can be measured.
Use a doubling/halving technique when increasing or decreasing gains. If the PID gains are set to
4, 1, and 0 respectively, and you are going to reduce them, try 2, 0.5, and 0. If the system now
undershoots, try gains of 3, 0.75, and 0 respectively. Refer to the section,
Gain," p.
42
good to have the sampling frequency set to two seconds.
32.
"Sampling Frequency," p.
"Throttling Range and
CNT-SVX08F-EN
34.