Instructions
9.2 PID_3Step
PID control
328 Function Manual, 03/2017, A5E35300227-AC
Retain.TransitTime REAL 30.0 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.
Retain.CtrlParams.SetByUser BOOL FALSE 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
Retain.CtrlParams.Gain REAL 1.0 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.
Retain.CtrlParams.Ti REAL 20.0
• Ti > 0.0: Active integration time in seconds
• Ti = 0.0: Integral action is deactivated
Retain.CtrlParams.Td REAL 0.0
• Td > 0.0: Active derivative action time in seconds
• Td = 0.0: Derivative action is deactivated
Td is retentive.
Retain.CtrlParams.TdFiltRatio REAL 0.2 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
dominant time constant.
• > 1.0: The greater the coefficient, the longer the effect of
the derivative action is delayed.
TdFiltRatio is retentive.
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