Siemens SIMATIC S7-1200 Function Manual page 423

Tag
PIDSelfTune.TIR.Output-
OffsetCool
PIDSelfTune.TIR.WaitFor-
ControlIn
PIDSelfTune.TIR.ControlIn-
Ready
PIDSelfTune.TIR.Finish-
ControlIn
PIDCtrl.IOutputOld
PID control
Function Manual, 03/2017, A5E35300227-AC
Data type Default
REAL 0.0
BOOL FALSE
BOOL FALSE
BOOL FALSE
REAL 0.0
Description
Tuning offset cooling of the PID output value
TIR.OutputOffsetCool is added to the value that results
from PidOutputSum for the cooling branch.
To receive a positive offset at the outputs for cooling,
define a negative value for TIR.OutputOffsetCool.
The resulting values at the outputs for cooling are the
result of the configured output scaling (Struktur Con-
fig.Output.Coool).
This tuning offset can be used in controllers with activated
cooling output (Config.ActivateCooling = TRUE) for fine
tuning heating. If the outputs for heating are not active at
the setpoint that is to be tuned (PidOutputSum < 0.0), fine
tuning heating is not possible. In this case, define a nega-
tive tuning offset cooling which is less than the PID output
value (PidOutputSum) at the setpoint in the steady state
before you start tuning. This step increases the values at
the outputs for cooling and activates the outputs for heat-
ing (PidOutputSum > 0.0). Fine tuning heating is now
possible.
When fine tuning is complete, TIR.OutputOffsetCool is
reset to 0.0.
Major changes at TIR.OutputOffsetCool in one step can
result in temporary overshoots.
Config.Output.Cool.PidUpperLimit ≥ PIDSelfTune
.TIR.OutputOffsetCool ≥ Con-
fig.Output.Cool.PidLowerLimit
Waiting with fine tuning after reaching the setpoint
If TIR.WaitForControlIn = TRUE, fine tuning waits in be-
tween reaching the setpoint (TIR.State = 500 or 600) and
calculation of the standard deviation (TIR.State = 700 or
800) until a FALSE -> TRUE edge is given at
TIR.FinishControlIn.
TIR.WaitForControlIn can be used for simultaneous fine
tuning of several controllers in multi-zone applications to
synchronize tuning of the individual zones. It ensures that
all zones have reached their setpoints before the actual
tuning starts. The influence of thermal connections be-
tween the zones on tuning can be reduced in this way.
TIR.WaitForControlIn is only effective if fine tuning is
started from automatic mode with PIDSelfTune.TIR.RunIn
= FALSE.
If TIR.WaitForControlIn = TRUE, PID_Temp sets
TIR.ControlInReady = TRUE as soon as the setpoint has
been reached and waits with additional tuning steps until a
FALSE -> TRUE edge is given at TIR.FinishControlIn.
If TIR.ControlInReady = TRUE, a FALSE -> TRUE edge at
TIR.FinishControlIn stops the wait and fine tuning re-
sumes.
Integral action in last cycle
Instructions
9.3 PID_Temp
423