Siemens SIMATIC S7-1200 Function Manual page 327

Tag
PIDSelfTune.TIR.RunIn
PIDSelfTune.TIR.Calculate-
Params
PIDSelfTune.TIR.TuneRule
PIDSelfTune.TIR.State
PID control
Function Manual, 03/2017, A5E35300227-AC
Data type Default
BOOL FALSE
BOOL FALSE
INT 0
INT 0
Description
With the RunIn tag, you can specify that fine tuning can also
be performed without pretuning.
RunIn = FALSE
•
Pretuning is started when fine tuning is started from in-
active or manual mode.
If fine tuning is started from automatic mode, the system
uses the existing PID parameters to control to the set-
point.
Only then will fine tuning start. If pretuning is not possi-
ble, PID_3Step switches to the mode from which tuning
was started.
RunIn = TRUE
•
The pretuning is skipped. PID_3Step attempts to reach
the setpoint with the minimum or maximum output value.
This can produce increased overshoot. Only then will fi-
ne tuning start.
RunIn is set to FALSE after fine tuning.
The properties of the controlled system are saved during
tuning. If CalculateParams = TRUE, the PID parameters are
recalculated on the basis of these properties. The PID pa-
rameters are calculated using the method set in TuneRule.
CalculateParams is set to FALSE following calculation.
Methods used to calculate parameters during fine tuning:
TIR.TuneRule = 0: PID automatic
•
TIR.TuneRule = 1: PID fast
•
TIR.TuneRule = 2: PID slow
•
TIR.TuneRule = 3: Ziegler-Nichols PID
•
TIR.TuneRule = 4: Ziegler-Nichols PI
•
TIR.TuneRule = 5: Ziegler-Nichols P
•
The TIR.State tag indicates the current phase of fine tuning:
State = -100 Fine tuning is not possible. Pretuning will
•
be performed first.
State = 0: Initialize fine tuning
•
State = 200: Calculate the standard deviation
•
State = 300: Attempt to reach the setpoint with the max-
•
imum or minimum output value
State = 400: Attempt to reach the setpoint with existing
•
PID parameters (if pretuning was successful)
State = 500: Determine oscillation and calculate parame-
•
ters
State = 9900: Fine tuning successful
•
State = 1: Fine tuning not successful
•
Instructions
9.2 PID_3Step
327