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MANUAL PID TUNING
Some applications will require manual PID tuning. First time PID control user's should review the PID
Fundamentals described in Appendix A. Also review Auto Tune Optimization above to gain an
understanding of the effect that Gain and Reset have on the PID controller.
1.
Configure the module for the type of Temperature Sensor (V5017). Then program the PID
Control Period (V5020) and the Temperature SetPoint (V5001). See page 2.20 for a description
of PID Control Period.
2.
If heating control action is required then turn off bit 1 in the Mode Word (V5000). This will cause
the output to increase when the temperature is below the SetPoint. Turn on bit 1 for cooling
control. In this case, the output will increase when the temperature is above the SetPoint.
3.
Set the Reset (V5007) and Rate (V5010) to zero to disable all integral and derivative action. Set
the Gain (V5006) to 0200 (20.0). Set the PID Control Period (V5020) to 20 (2.0 seconds).
4.
Make the temperature stabilize near the most commonly used SetPoint (two methods for doing
this are described on page 4.1). Place the temperature controller in PID Control mode by turning
on bit 4 in the Mode Word.
5.
Prepare to plot the temperature as it varies with time (in seconds).
6.
Generate an upset in the loop and adjust the Gain (V5006) until the temperature cycles with a
constant amplitude (a/b = 1). If the amplitude increases (a/b < 1) following the upset then the
Gain must be reduced. If the amplitude decreases (a/b > 1) following the upset then the Gain
should be increased.
An upset can be generated by changing the SetPoint. After the temperature begins to move
towards the new SetPoint, return the SetPoint to the previous value.
7.
The gain which produces oscillations with a constant amplitude is called the ultimate gain, Ku.
The period of these oscillations is called the ultimate period, Pu.
SetPoint
TIME (seconds)
a
b
LOOP TUNING
Pu
4.5
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