IDEC MICROSmart FC6A Series Ladder Programming Manual page 415

Process variable (PV) ≥ set point (SP) + AT bias setting value
When the AT bias setting is set to 20°C, fluctuations will start when the process variable (PV) reaches a temperature 20°C higher
than the set point (SP).
Temperature
SP+20
4
SP
■To execute auto tuning (AT)
To execute auto tuning, turn on the auto tuning execution flag (S3+6) when the PIDA instruction input is on. The values for P, I,
and D will be automatically calculated. While auto tuning is executing, 1 is stored in the operation status (S1+2).
When auto tuning ends, the auto tuning execution flag (S3+6) turns off automatically, 2 is stored in the operation status (S1+2),
and the auto tuning completed output (S3+7) turns on.
■To cancel auto tuning (AT) execution
To cancel auto tuning while it is executing, turn off the auto tuning execution flag (S3+6). When the auto tuning execution flag
(S3+6) is turned off, auto tuning stops, 2 is stored in the operation status (S1+2), and the auto tuning completed output (S3+7)
turns on.
If auto tuning is canceled without completing, the values for P, I, and D are restored to the values before auto tuning was
executed.
AT
1 2
FC6A S MICROS
ERIES MART
1. Measuring PID constants
2. Calculate PID constants
3. Control with the PID constants set with AT
4. AT bias setting value (20)
AT: When the AT execution bit is turned on
Time
3
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ADDER ROGRAMMING ANUAL
19: PID C
ONTROL
FC9Y-B1726
I
NSTRUCTION
19-25