Siemens SIMATIC S7-1200 Function Manual page 328

Instructions
9.2 PID_3Step
Tag
Retain.TransitTime
Retain.CtrlParams.SetByUser
Retain.CtrlParams.Gain
Retain.CtrlParams.Ti
Retain.CtrlParams.Td
Retain.CtrlParams.TdFiltRatio
328
Data type Default
REAL 30.0
BOOL FALSE
REAL 1.0
REAL 20.0
REAL 0.0
REAL 0.2
Description
Motor transition time in seconds
Time in seconds the actuating drive requires to move the
valve from the closed to the opened state.
TransitTime is retentive.
If SetByUser = FALSE, the PID parameters are determined
automatically and PID_3Step operates with a dead zone at
the output value. The dead band width is calculated during
tuning on the basis of the standard deviation of the output
value and saved in Retain.CtrlParams.OutputDeadBand.
If SetByUser = TRUE, the PID parameters are entered
manually and PID_3 Step operates without a dead zone at
the output value. Retain.CtrlParams.OutputDeadBand = 0.0
SetByUser is retentive.
Active proportional gain
To invert the control logic, use the Config.InvertControl tag.
Negative values at Gain also invert the control logic. We
recommend you use only InvertControl to set the control
logic. The control logic is also inverted if InvertControl =
TRUE and Gain < 0.0.
Gain is retentive.
Ti > 0.0: Active integration time in seconds
•
Ti = 0.0: Integral action is deactivated
•
Ti is retentive.
Td > 0.0: Active derivative action time in seconds
•
Td = 0.0: Derivative action is deactivated
•
Td is retentive.
Active derivative delay coefficient
The derivative delay coefficient delays the effect of the de-
rivative action.
Derivative delay = derivative action time × derivative delay
coefficient
0.0: Derivative action is effective for one cycle only and
•
therefore almost not effective.
0.5: This value has proved useful in practice for con-
•
trolled systems with one dominant time constant.
> 1.0: The greater the coefficient, the longer the effect of
•
the derivative action is delayed.
TdFiltRatio is retentive.
Function Manual, 03/2017, A5E35300227-AC
PID control