26
Chapter 6 TUNING
• Use auto-tuning.
For details on how to use auto-tuning, see “
6-4 Auto-tuning
.”
• Reset the PID values, and resume self-tuning.
Set parameter item
C
t
R
l
(control method) to “2”.
Reset the PID values to the factory settings (
P
= 5.0,
I
= 120,
d
= 30).
Set
C
t
R
l
to “1”, and resume self-tuning.
Handling Precautions
●
In the Case of Interference Control Targets
Control targets may be located to the left or right (above or below), and re-
sponse may slow down as a result of mutual tuning being adversely affected by
respective changes in temperature.
If this happens, either use control by fixed PID values (
C
t
R
l
= 2), or set
parameter item (
S
b
) to “0”.
●
In the Case of Control Targets Where Disturbance Is Generated Intermittently
Tuning results are sometimes adversely influenced when tuning control targets
where intermittent temperature drops occur (e.g. during sealing on packaging
machines).
If this happens, either use control by fixed PID values (
C
t
R
l
= 2), or set
parameter item (
S
b
) to “0”.
6-4
Auto-tuning
Use the auto-tuning function in the following instances:
• To automatically calculate PID constants by control by fixed PID value (
C
t
R
l
= 2)
• When startup is slow in self-tuning control
• When response startup is slow in self-tuning control
The auto-tuning function can be used in either of self-tuning control (
C
t
R
l
= 1) or
control by fixed PID values (
C
t
R
l
= 2).
●
Procedure
Hold the
PARA
key down for at least 3 seconds in the RUN mode and with the SP
value set to enter the parameter setup mode.
Press the
PARA
key with
C
t
R
l
set to “1” or “2”.
A
t
(auto-tuning) is displayed. Set “1”.
If “1” is already set, set to “0” then back to “1”.
Auto-tuning can also be stopped by using the external switch input function. To forcibly
cancel auto-tuning midway, either set
A
t
to “0”, or set the controller to the READY
mode.
Auto-tuning indication
The lower right LED after the 1st digit in the lower
display blinks when the auto-tuning function is ON.
The LED goes out when tuning ends.
2
5
0
1
2
0
RDY
PV
SP
LED
1
2
3
1
2
3
