Mitsubishi Electric MELSEC Q Series Reference Manual page 510

(2) When no system switching occurs in Redundant CPUs even though the cable
of the CC-Link IE Controller Network module is disconnected
The following flowchart shows the procedures to be taken when no system switching occurs in Redundant CPUs
even if the cable of the CC-Link IE Controller Network module is disconnected.
No system switching occurs in Redundant
CPUs even though the CC-Link IE controller
network module cable is disconnected.
Is the POWER LED on the
standby system power supply
module on?
Has a stop error occurred
in the standby system CPU?
Has an error occurred
in the standby system
CC-Link IE controller
network module?
Data-link-error-induced
system switching disable flag
(SB0017)
Is the tracking cable
disconnected?
Refer to the troubleshooting in the following manual.
QnPRHCPU User's Manual
(Redundant System)
508
On
No
No
OFF (Enable)
No
End
Supply power.
Review the system configuration so that the total
current does not exceed the rated output current
of the power supply module.
QCPU User's Manual
(Hardware Design, Maintenance and
Off
Inspection)
The power supply module hardware may be faulty.
Please consult your local Mitsubishi
representative.
Check the error details and take corrective actions.
Yes
QCPU User's Manual
(Hardware Design, Maintenance
and Inspection)
Yes
Check the error details and take corrective actions.
Page 511, Section 10.2
ON Even if a data link error is detected, no system
(Disable) switching request will be issued to the control
system CPU.
Set the Data-link-error-induced system switching
disable flag (SB0017) to OFF.
Yes
Connect the tracking cable properly.