6. OPERATIONS OF THE BASIC FUNCTIONS
6-8 IMR02C15-E4
6.2 Autotuning (AT)
The Autotuning (AT) function automatically measures, computes and sets the optimum PID values.
îš„ Caution for using the Autotuning (AT)
• When a temperature change (UP and/or Down) is 1 °C or less per minute during Autotuning (AT),
Autotuning (AT) may not be finished normally. In that case, adjust the PID values manually. Manual
setting of PID values may also be necessary if the set value is around the ambient temperature or is
close to the maximum temperature achieved by the load.
• If the manipulated output value may be limited by the Output limiter setting, the optimum PID
values may not be calculated by Autotuning (AT).
îš„ Requirements for Autotuning (AT) start
Start the Autotuning (AT) when all following conditions are satisfied:
To start Autotuning (AT), go to Parameter setting mode.
PID control
Operation state
RUN
Parameter setting
Output limiter high ≥ 0.1 %, Output limiter low ≤ 99.9 %
[Heat/Cool control type: Output limiter high (heat-side) ≥ 0.1 %,
Output limiter high (cool-side) ≥ 0.1 %]
Input value state The Measured value (PV) is not underscale or over-scale.
îš„ Requirements for Autotuning (AT) cancellation
If the Autotuning (AT) is canceled according to any of the following conditions, the controller
immediately changes to PID control. The PID values will be the same as before Autotuning (AT) was
activated.
When the PID/AT transfer is changed to the PID control.
When the RUN/STOP mode is changed to the STOP mode.
Operation state
When the Auto/Manual mode is changed to the Manual mode.
Parameter changing
When the PV bias or the PV digital filter is changed.
Parameter changing
When the Output limiter value is changed.
Input value state When the Measured value (PV) goes to underscale or over-scale.
AT execution time When the Autotuning (AT) does not end in 9 hours after Autotuning (AT) started.
Power failure
When the power failure of more than 20 ms occurs.
(10 ms or more for RB100 with 24V AC/DC power supply.)
Instrument error When the instrument is in the FAIL state.
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