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Alarm 2 Failure Transfer is activated as the controller enters failure mode. Thereafter the
alarm 2 will transfer to the ON or OFF state preset by A2FT.Alarm 2 Failure Transfer is activated
as the controller enters failure mode.
Exception: If Loop Break (LB) alarm or sensor Break (SENB) alarm is configured for
A2FN, the alarm 2 will be switched to ON state independent of the setting of A2FT. If Dwell Timer
(TIMR) is configured for A2FN, the alarm 2 will not perform failure transfer.
4.3.1.1.4.8 Bumpless Transfer
The bumpless transfer function is available for output 1 and output 2 (provided that OUT2
is configured as COOL).
Bumpless Transfer is enabled by selecting BPLS for O1FT and/or O2FT and activated as one
of the following cases occurs.
Power starts (within 2.5 seconds).
The controller enters the failure mode.
The controller enters the manual mode.
The controller enters the calibration mode.
As the bumpless transfer is activated, the controller will transfer to open-loop control and
uses the previous averaging value of MV1 and MV2 to continue control.
Without Bumpless Transfer
Since the hardware and software need time to be initialized, the control is abnormal as the
power is recovered and results in a large disturbance to the process. During the sensor breaks, the
process loses power.
Figure 4-31.Without Bumpless Transfer
Without Bumpless Transfer
After bumpless transfer is configured with the correct control variables applied, the
disturbance is small when the power is recovered. During the sensor breaks, the controller
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