Instruction manual

45
[How to cancel auto-tuning]
Available only during AT Perform
[AT is performing]
Press the Key while holding down the
key.
The unit enters the PID parameter setting mode,
+ and AT Perform/Cancel item is indicated.
[PID parameter setting mode]
AT Perform/Cancel selection
Press the key.
Press the Key.
Auto-tuning is cancelled, and the controller
reverts to the Program control run mode.
[Program control run mode]
8. Control and Alarm action
8.1 P, I, D, ARW action
(1) Proportional band (P)
Proportional action is the action which the control output (OUT) varies in proportion to
the deviation between the SV (desired value) and the PV (processing temperature).
If the proportional band is narrowed, even if the output changes by a slight variation
of the processing temperature, better control results can be obtained as the offset
decreases.
However, if the proportional band is narrowed too much, even slight disturbances
may cause variation in the processing temperature, control action changes to
ON/OFF control and the so-called hunting phenomenon occurs.
Therefore, when the processing temperature comes to the balanced position near
the SV and a constant temperature is maintained, the most suitable value is selected
by gradually narrowing the proportional band while observing the control results.
(2) Integral time (I)
Integral action is used to eliminate offset. When the integral time is shortened, the
returning speed to the SV (desired value) is accelerated. However, the cycle of
oscillation is also accelerated and the control becomes unstable.
PTN PV
Actual temp.
STEP SV
Step SV
PTN PV
STEP SV
PTN PV
STEP SV
PTN PV
Actual temp.
STEP SV
Step SV