The Phases Of Controller Tuning - Siemens SIMATIC Manual

Controller Tuning in FB 58 "TCONT_CP"
3.4

The Phases of Controller Tuning

During tuning, several phases are run through in the block algorithm. The PHASE
parameter indicates which phase the block is currently in.
You start the tuning as follows (see Section 3.6, Page 3-8):
•
Setting TUN_ON = TRUE prepares the controller for tuning. The controller
changes from Phase 0 to 1.
•
After waiting some time in phase 1, either set a setpoint step change at the
SP_INT parameter or set TUN_ST = TRUE. The controller outputs a
manipulated variable changed by the value TUN_DLMN and begins to search
for the point of inflection.
PHASE
0
1
2
3 (1 cycle)
4 (1 cycle)
5 (1 cycle)
7
The schematic below illustrates the phases of tuning as a result of a setpoint step
change from the ambient temperature to the operating point:
PHASE PHASE = 1
= 0
Temp.
LMN
TUN_DLMN
Point of inflection
Cold process
state
3-4
Description
No tuning; automatic or manual mode
Ready to start tuning; check parameters, wait for excitation, measure the
sampling times
Actual tuning: Wait to detect point of inflection at a constant controller output
value. Entry of the sampling time in the instance DB.
Calculation of the process parameters. The controller parameters valid prior
to tuning are saved.
Controller design
Bring the controller to the new manipulated variable
Check the process type
PHASE = 3, 4, 5 PHASE =7
(each one cycle)
PHASE
= 2
TUN_ON: Reset by Block
PHASE = 0
SP
PV
LMN
PID Temperature Control
A5E00125039-02
Warm process
state
(Operating point)
t
t