Siemens SIMATIC S7-1200 Function Manual page 358

Instructions
9.2 PID_3Step
Tag
CycleTime.Value
CtrlParamsBackUp.SetByUser BOOL
CtrlParamsBackUp.Gain
CtrlParamsBackUp.Ti
CtrlParamsBackUp.Td
CtrlParamsBackUp.TdFiltRatio REAL
CtrlParamsBack-
Up.PWeighting
CtrlParamsBack-
Up.DWeighting
CtrlParamsBackUp.Cycle
CtrlParamsBack-
Up.InputDeadBand
PIDSelfTune.SUT.Calculate-
SUTParams
PIDSelfTune.SUT.TuneRule-
SUT
PIDSelfTune.SUT.State
PIDSelfTune.TIR.RunIn
358
Data type Default Description
REAL 0.1 PID_3Step sampling time in seconds
CycleTime.Value is determined automatically and is usually equiv-
alent to the cycle time of the calling OB.
FALSE Saved value of Retain.CtrlParams.SetByUser.
You can reload values from the CtrlParamsBackUp structure with
Config.LoadBackUp = TRUE.
REAL 1.0 Saved proportional gain
REAL 20.0 Saved integral action time
REAL 0.0 Saved derivative action time
0.0 Saved derivative delay coefficient
REAL 0.0 Saved proportional action weighting
REAL 0.0 Saved derivative action weighting
REAL 1.0 Saved sampling time of PID algorithm
REAL 0.0 Saved dead zone width of the control deviation
BOOL FALSE The properties of the controlled system are saved during tuning. If
CalculateSUTParams = TRUE, the PID parameters are recalculat-
ed on the basis of these properties. The PID parameters are calcu-
lated using the method set in TuneRuleSUT. CalculateSUTParams
is set to FALSE following calculation.
INT 1 Methods used to calculate parameters during pretuning:
•
•
•
•
•
•
INT 0 The SUT.State tag indicates the current phase of pretuning:
BOOL FALSE
•
•
TuneRuleSUT = 0: PID fast I
TuneRuleSUT = 1: PID slow I
TuneRuleSUT = 2: Chien, Hrones and Reswick PID
TuneRuleSUT = 3: Chien, Hrones, Reswick PI
TuneRuleSUT = 4: PID fast II
TuneRuleSUT = 5: PID slow II
RunIn = FALSE
Pretuning is started when fine tuning is started from inactive or
manual mode.
If fine tuning is started from automatic mode, the system uses
the existing PID parameters to control to the setpoint.
Only then will fine tuning start. If pretuning is not possible,
PID_3Step switches to "Inactive" mode.
RunIn = TRUE
The pretuning is skipped. PID_3Step attempts to reach the set-
point with the minimum or maximum output value. This can
produce increased overshoot. Only then will fine tuning start.
RunIn is set to FALSE after fine tuning.
Function Manual, 03/2017, A5E35300227-AC
PID control