Mitsubishi Electric MELSEC iQ-R Series User Manual page 164

■When the READY LED of the CPU module in one of the systems is flashing
Do not power off the other system.
The system may start up without checking the system consistency even when a mismatch exists between the two systems.
( Page 414 Execution timing)
■If the system configurations differ between the two systems (for example, the insertion status
of an SD memory card)
It may take time to start communications between the two systems. Check that the system configuration is the same between
the two systems following the procedure for starting up both systems simultaneously, and then start up the redundant system.
( Page 54 Starting up both systems simultaneously)
■When an SD memory card is used
• Do not power off the system, reset the CPU module, or remove the SD memory card during an access to the SD memory
card. A stop error may occur in both systems and the systems may not be started as a redundant system.
• If the system is powered off, the CPU module is reset, or the SD memory card is removed during an access to the SD
memory card, the data in the SD memory card may corrupt. In this case, diagnostics of the SD memory card (such as a file
system check or restoration processing) is performed when the CPU module is powered off and on or is reset.
• During diagnostics of the SD memory card, tracking communications are disabled. If diagnostics of the SD memory card on
the other system are not completed in the timeout period set in "Other system Start-up Timeout Setting", a stop error occurs
on the own system. In this case, a stop error occurs in the other system as well. As a result, a stop error occurs in both
systems and the systems cannot be started as a redundant system. Restart both systems.
• In a redundant system with redundant extension base unit, the control/standby system start-up setting is invalid. As a
result, if the own system is started up while the SD memory card diagnostics is being executed in the other system, the own
system may start up as a control system. Even when both systems are started up simultaneously, if the SD memory card
diagnostics is executed in the other system, the own system may start up first as the control system, as in the case of the
systems starting up one by one. In this case, when the SD memory card diagnostics of the other system finishes during
initialization of the own system, a stop error is detected in the other system.
If the SD memory card diagnostics of the other system takes time, only the own system can be started up.
( Page 165 When one system is started automatically even though a tracking communication error has
occurred)
11 BASIC CONCEPT OF REDUNDANT SYSTEM
162
11.6 System Determination