Process control instructions
951
Part III FP Instructions
Auto-tuning bias value
If a bias value has been set, auto-tuning will be performed with a temporary set point value SP’.
In reverse operation, SP' is the difference of the set point value SP and the auto-tuning bias value. The
auto-tuning bias value can be used to control excessive temperature rise during auto-tuning.
In forward operation, SP' is the sum of the set point value SP and the auto-tuning bias value.
(SP’)
(SP’)
Set value
(SP)
Temperature
Auto-tuning bias value
Auto-tuning in
reverse operation
Auto-tuning in
forward operation
Temperature
Set value
(SP)
Auto-tuning bias value
During auto-tuning
During auto-tuning
PID control
PID control
Time
Time
KP, TI and TD calculation
KP, TI and TD calculation
NOTE
Auto-tuning is peformed with SP’ even if the measured process value is close to the set point
value SP when auto-tuning starts.