Siemens SIMATIC S7-1200 Function Manual page 480

Instructions
9.4 PID basic functions
Save controller parameters SAVE_PAR
I f you classify the current controller parameters as utilizable, you can save these before a
manual change in structure parameters provided specifically for this in the instance DB of the
instruction TCONT_CP. If you optimize the controller, the saved parameters are overwritten
by the values that were valid prior to tuning.
PFAC_SP, GAIN, TI, TD, D_F, CONZ_ON and CONZONE are written to the structure
PAR_SAVE.
Reloading Saved Controller Parameters UNDO_PAR
The last controller parameter settings you saved can be activated for the controller again
using this function (in manual mode only).
Change between PI and PID parameters LOAD_PID (PID_ON)
Following tuning, the PI and PID parameters are stored in the PI_CON and PID_CON
structures. Depending on PID_ON, you can use LOAD_PID in manual mode to write the PI
or PID parameters to the effective controller parameters.
PID parameters PID_ON = TRUE
•
•
•
Note
The controller parameters are only written back to the controller with UNDO_PAR or
LOAD_PID, if the controller gain is not equal to 0:
With LOAD_PID, the parameters are only copied if the corresponding GAIN <> 0 is (either
the PI or PID parameters). This strategy takes into account the situation that no tuning has
yet been made or that PID parameters are missing. If PID_ON = TRUE and
PID.GAIN = FALSE, PID_ON is set to FALSE and the PI parameter is copied.
• D_F, PFAC_SP are preset by the the tuning. These can then be modified by the user.
LOAD_PID does not change these parameters.
• With LOAD_PID, the control zone is always recalculated
(CON_ZONE = 250/GAIN), even if CONZ_ON = FALSE.
See also
Operating principle of the pulse generator (Page 481)
Block diagram TCONT_CP (Page 484)
480
GAIN = PID_CON.GAIN
TI = PID_CON.TI
TD = PID_CON.TD
PI parameters PID_ON = FALSE
GAIN = PI_CON.GAIN
•
TI = PI_CON.TI
•
Function Manual, 03/2017, A5E35300227-AC
PID control