7-18 EB 6493 EN
Start-up and conguration at the device
7.3 Tuning the control parameters
The controller must be adapted to the dynamic behavior of the controlled system over the pa-
rameters KP, TN and TV to ensure that errors caused by disturbances can be eliminated or
largely suppressed. It is possible to tune these parameters either by performing the function
-CO- TUNE Start-up adaptation (see section7.3.3) or by manual tuning.
7.3.1 Empirical tuning method
The following empirical method can be used to tune control parameters. This method is mere-
ly intended as a guide and not a one-size-ts-all solution.
Proceed as follows for a PI controller
1. Switch to manual mode ( ).
2. In the CNTR menu, set the function -CO- C.PID = PICP.YP.
3. In the PAR menu, set the parameters KP = 0.1 and TN = 9999s.
4. In the operating level, set the set point W to the required value.
Î Press
to select W and use the cursor keys ( , ). to set the value.
5. In the operating level, change the manipulated variable Y so that the controlled variable
X has the same value as the set point W (error Xd = 0).
Î Press
to select Y and use the cursor keys ( , ) to set the value.
6. Switch to automatic mode (
).
7. In the PAR menu, step up the KP parameter until the controlled system shows a tendency
to oscillate.
Every time the KP increases, let the controlled system oscillate, e.g. by making small
changes to the set point.
8. In the PAR menu, reduce the KP parameter again until the controlled system stops oscillat-
ing.
9. In the PAR menu, step up the TN parameter until the controlled system shows a tendency
to oscillate. Every time the TN increases, let the controlled system oscillate, e.g. by mak-
ing small changes to the set point.
10. In the PAR menu, reduce the TN parameter again until the controlled system stops oscillat-
ing.
11. Change the set point slightly and check the transient behavior. If necessary, retune KP
and TN until the closed loop shows a satisfactory control behavior.
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