Integralresetmode V2 Tag - Siemens SIMATIC S7-1200 Function Manual

Instructions
9.1 PID_Compact
9.1.4.12

IntegralResetMode V2 tag

The IntegralResetMode tag determines how the integral action PIDCtrl.IntegralSum is pre-
assigned:
● When switching from "Inactive" operating mode to "Automatic mode"
● With edge TRUE -> FALSE at parameter Reset and parameter Mode = 3
This setting only works for one cycle and is only effective if the integral action is activated
(Retain.CtrlParams.Ti > 0.0 tag).
IntegralReset- Description
Mode
0 Smooth
The value of PIDCtrl.IntegralSum is pre-assigned so that the switchover is bumpless, which means
"Automatic mode" starts with the output value = 0.0 (parameter Output) and there is no jump of the
output value regardless of the control deviation (setpoint – actual value).
1 Delete
We recommend setting the weighting of the proportional action (Retain.CtrlParams.PWeighting) to 1.0 if
this option is used.
The value of PIDCtrl.IntegralSum is deleted. Any control deviation will cause a jump change of the out-
put value. The direction of the output value jump depends on the configured weighting of the propor-
tional action (Retain.CtrlParams.PWeighting tag) and the control deviation:
Proportional action weighting = 1.0:
•
Output value jump and control deviation have identical signs.
Example: If the actual value value is smaller than the setpoint (positive control deviation), the output
value jumps to a positive value.
Proportional action weighting < 1.0:
•
For large control deviations, the output value jump and control deviation have identical signs.
Example: If the actual value is much smaller than the setpoint (positive control deviation), the output
value jumps to a positive value.
For small control deviations, the output value jump and control deviation have different signs.
Example: If the actual value value is just below the setpoint (positive control deviation), the output
value jumps to a negative value. This is usually not desirable, because it results in a temporary in-
crease in the control deviation.
The smaller the configured weighting of the proportional action, the greater the control deviation
must be to receive an output value jump with identical sign.
We recommend setting the weighting of the proportional action (Retain.CtrlParams.PWeighting) to 1.0
when this option is used. Otherwise, you may experience the undesirable behavior described for small
control deviations. Alternatively, you can also use IntegralResetMode = 4. This option guarantees iden-
tical signs of the output value jump and control deviation independent of the configured weighting of the
proportional action and the control deviation.
2 Hold
The value of PIDCtrl.IntegralSum is not changed. You can define a new value using the user program.
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Function Manual, 03/2017, A5E35300227-AC
PID control