When Starting Up One System First - Mitsubishi Electric MELSEC iQ-R-R00CPU User Manual

■When the READY LED of the CPU module in one of the systems is flashing
Do not power off the CPU module in the other system.
The system may start up without checking the system consistency even when the conditions between the both systems do
not match. ( Page 476 Execution timing)
■When the configuration between the both systems do not match
When the configuration (such as insertion of an SD memory card) between the both systems do not match, it may take time to
start communications between the both systems. Check that the both system configurations match in the process of starting
up both systems at a time, and then start up a redundant system. ( Page 422 Starting up both systems at a time)
■Using an SD memory card
Do not power off or reset the CPU module, or remove an SD memory card during an access to the SD memory card. A stop
error may occur on both systems and the systems may not be started as a redundant system.
If the CPU module is powered off or reset or an SD memory card is removed during an access to the SD memory card, the
data in the SD memory card may be corrupted. In this case, diagnostics of the SD memory card (such as a file system check
or restore 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. If diagnostics of the SD memory card takes time on the other system, a stop error occurs on the other
system as well. In this case, a stop error occurs on both systems and the systems cannot be started as a redundant system.
Reset and restore both systems.
Even though diagnostics of the SD memory card takes time on the other system, only the own system can be
started. ( Page 413 When one system is started automatically even though a tracking communication
error has occurred)

When starting up one system first

One of the system A and system B can be started up first.
How to start one system first
Perform one of the following operations to the CPU module that is waiting for the start-up of the other system. The system of
the CPU module will be started as the control system.
■Online operation
Perform the following operation on the engineering tool.
[Online]  [Redundant PLC Operation]  [Redundant Operation]
Select "Forced Start of Control System while Waiting for Other System to Start" and click the [Execute] button.
■Switch operation
Set the RUN/STOP/RESET switch of the CPU module to the RUN, STOP, and then the RUN position again.
Set "Control System Start-up Setting (Switch Operation)" to "Enable" in the CPU parameter in advance. ( Page 485
Redundant System Operation Setting)
■Operation with the input (X)
Turn on the input (X) set with the parameters.
Set "Control System Start-up Setting (Input (X))" to "Enable" in the CPU parameter in advance. ( Page 485 Redundant
System Operation Setting)
26.7 Determination of Control System/Standby System
26 BASIC CONCEPT
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