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5.6.4 Auto-Tuning
Automatic tuning measures the controlled section’s temperature characteristics and thermal response rate and
then determines the required PID time constants.
(If the
[C-MD]
control type is PID, it is displayed.)
This operation will stop automatically if an
[OPEN]
error occurs during auto-tuning.
To stop auto-tuning, change the setting to OFF.
(In this case, the P, I, D values before auto-tuning are retained.)
5.6.4.1 Auto-Tuning ON/OFF
[PAR2 → AT]
Auto Tuning automatically stores the PID time constants when completed. These PID time constants can then be
modified according to their usage environment. Default setting: OFF.
When auto-tuning is in progress, the
AT
indicator on the controller’s front flashes every 1 second. When auto-
tuning is completed, the
AT
indicator will automatically turn off, and the auto-tuning parameter will return to the
OFF
position.
Note: When auto tuning is in progress, and the [DI-K] digital input button function is set to RUN / STOP [STOP] or auto-tuning
RUN / STOP [AT] and the digital input terminal [DI-1] function switches RUN / STOP [STOP] or AUTO / MANUAL control
selection [MAN], auto-tuning stops automatically when the affected DI is entered, or a sensor disconnection error occurs.
(Resets the PID used before auto-tuning).
Setting
Description
OFF
Auto-tuning is off or finished
ON
Auto-tuning is in progress
Note: Auto-tuning will continue even if the temperature value exceeds or falls within the input range. When auto-tuning
is in progress, the parameters can only be referenced but not modified. Auto-tuning is not available for manual control.
5.6.5 Auto-Tuning Mode Settings
[PAR3 → AtT]
Auto tuning is available in [TUN1] mode (based on SV) or [TUN2] mode (based on 70% of SV), depending on the default
value used. Default setting: TUN1.
Auto-tuning period
Tun 1 mode
Tun 2 mode
Time (t)
SV
SV
70% of SV
Time (t)
Auto-tuning period
Setting
Description
TUN1
Automatically tunes and derives the PID time constant based on the Set Value
(SV)
.
TUN2
Automatically tunes and derives the PID time constant based on 70% of the Set Value
(SV)
.
Note: In cooling control mode, [TUN2] mode calculates 70% based on 0. If SV = –100, it occurs at [TUN2] –70.