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SC100/200 Series Users Manual EM-6337-B Rev.15
11.2. BACKUP SETTING
11.2.1. AUTO / MANUAL SWITCHING
Manual Switching
Manual switching to the backup mode is always available by the front control button operations. Refer to the later sections
for the procedure.
Auto Switching
Control module and Backup module continuously monitors each other’s status. When an abnormality is detected at the con-
trol module (including when the Mv 2 output loop is open), the backup module automatically takes control of the Mv output.
AUTO SWITCHING CONDITION DETAIL
Mv 2 error
When the backup module detects a deviation greater than ±20% between the Mv 2 output and
its feedback signal at the control module.
Communication error
When the backup module fails to communicate with the control module for longer than 3
seconds.
CAUTION !
The Controller goes to the backup mode also when the power supply to the control module is lost. It is possible that the
Mv 2 output has been already declining before switched, and the backup module starts tracking the output at a slightly
lower level than the original output state.
11.2.2. BACKUP OUTPUT MODE (TRACK BACK / PRESET VALUE)
Track Back
The backup module provides the most updated normal output (when both the communication and the feedback signal de-
tected as normal) at the moment of switching.
Preset Value
The backup module provides a preset value output at the moment of switching.
A rate-of-change limit can be applied in transition to suppress a sudden change. The ramp output is overtook by manual
control if it is interrupted before the Mv 2 output reaches the preset value.
t
MV2
Error occurrs in
Control Module
Error Output
Switched to
Backup Module
Recovering the last
stored normal value
Backup module stores
the last normal value
t
MV2
Preset Value
Error occurrs in
Control Module
Switched to
Backup Module
Error Output
Tracking in preset ramp
rate until the MV2 reaches
the preset value
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