Siemens SIMATIC S7-1200 - Page 638

Technology instructions
10.2 PID control
S7-1200 Programmable controller
638 System Manual, V4.2, 09/2016, A5E02486680-AK
Operation modes
To change the mode of operation manually, the user needs to set the “Mode” in-out
parameter of the controller and activate it by setting “ModeActivate” from FALSE to TRUE
(rising edge triggered). You must reset “ModeActivate” before the next mode change; it does
not reset automatically.
Output parameter “State” shows the current operating mode and is set to the requested
“Mode” if possible. The “State” parameter cannot be changed directly; it is only changed
through the “Mode” parameter or automatic operating mode changes by the controller.
"Mode" /
"State"
Name
Description
0 Inactive The PID_Temp instruction:
• Deactivates the PID-algorithm and pulse width modulation
• Sets to "0" (FALSE) all controller outputs (OutputHeat, OutputCool, Out-
putHeat_PWM,OutputCool_PWM, OutputHeat_PER, OutputCool_PER), regardless of
configured output limits or offsets. You can reach this mode by setting “Mode” = 0,
“Reset” = TRUE, or by error.
1 Pretuning
(startup tun-
ing / SUT)
This mode determines the parameters during first start up of the controller.
Un
like the PID_Compact, for the PID_Temp, you must select if you require heating tuning,
cooling tuning, or both with the “Heat.EnableTuning” and “Cool.EnableTuning” parame-
ters.
You can activate "Pretuning" from Inactive, Automatic mode, or Manual mode.
If tuning is successful, PID_Temp switches to Automatic mode. If tuning is unsuccessful,
the switchover of the operating mode depends on “ActivateRecoverMode”.
2 Fine tuning
(tuning in run
/ TIR)
This mode determines the optimum parameterization of the PID controller at the setpoint.
Unlike the PID_Compact, for the PID_Temp, you must select if you require heating tuning
or cooling tuning with the “Heat.EnableTuning” and “Cool.EnableTuning” parameters.
You can activate "Finetuning" from Inactive, Automatic mode, or Manual mode.
If tuning is successful, PID_Temp switches to Automatic mode. If tuning is not successful,
the switchover of the operating mode depends on “ActivateRecoverMode”.
3 Automatic
mode
In Automatic mode (the standard PID control mode), the result of the PID-algorithm de-
termines the output values.
PID_Temp switches to Inactive if an error occurs and “ActivateRecoverMode” = FALSE. If
an error occurs and “ActivateRecoverMode” = TRUE, the switchover of the operating
mode depends on the error. Refer to PID_Temp instruction ErrorBit parameters
(Page 619) for further information.