Mitsubishi Electric MELSEC Q Series Reference Manual page 149

4 SETTING AND PROCEDURE BEFORE OPERATION
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(b) Setting the mode when performing the forward loop/reverse loop test on the
redundant system
When conducting the forward loop/reverse loop test on the redundant
system, set the operation mode of the redundant CPU to the backup mode
in advance.
When it the power supplies of both the systems cannot be powered on/off,
perform the forward loop/reverse loop test in the separate mode.
The table below lists the mode settings when conducting the forward
loop/reverse loop test on the redundant system.
Test target station
Non-test target station
The figure below shows the settings when the forward loop test is executed
on the system A (station No. 1) of the redundant system (in the backup
mode).
Remote I/O station
Power
QJ72
supply
LP25
module
Station
No. 3
Control system
(system A)
Power
Redundant
supply
CPU
module
Set the mode of the system A (station No. 0)
to "forward loop test."
Target station
In the backup
mode
Redundant
system In the separate
mode
In the backup
mode
Redundant
system
In the separate
mode
Remote I/O station
Remote I/O station
Power
QJ72
supply
LP25
module
Station
No. 2
Standby system
(system B)
Power
Station Redundant
supply
No. 0 CPU
module
Set the mode of the system B (station No. 1)
to "offline."
MELSEC-Q
Set-up
Set the mode to "Forward
loop test" or "Reverse
loop test".
Set the mode to "Offline".
Set the mode to "Online".
Set the mode to "Online".
Station
No. 1
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