Mitsubishi Electric MELSEC iQ-R Series User Manual page 60

Check method of information on system switching
This section describes how to check information on system switching when systems are switched.
When automatic system switching or manual system switching is performed, information on the system switching event can
be checked in the following ways.
Check method
Special register (SD)
CTRL LED and SBY LED of the remote head module
Event history
■Special register
The result of system switching and detailed information on system switching can be checked using the special register.
• Whether systems have been switched can be checked by checking 'System switching cause (when the systems are
successfully switched)' (SD1649). When system switching occurs, the system switching cause is stored in 'System
switching cause (when the systems are successfully switched)' (SD1649) of the control system and standby system each.
• When systems fail to be switched even though the system switching cause has occurred, the cause of failure in system
switching is stored in 'Cause of system switching failure' (SD1644).
The following table lists the special register related to system switching and whether to set or not each register in the remote
head module of new control system and new standby system each.
: Set, : Not set
SD number
SD1643
SD1644
SD1648
SD1649
SD1681
For details on the special register (SD), refer to the following.
Page 148 List of Special Register (SD) Areas
■CTRL LED and SBY LED of the remote head module
The following table lists the LED indication when system switching is completed successfully by a system switching cause.
Item When system switched from the control system to the
standby system
On  Off
CTRL LED
Off  On
SBY LED
The following table lists the LED indication when system switching is not completed successfully by a cause of system
switching failure
Item Control system
CTRL LED On or flashes
SBY LED Off
*1 This LED flashes when system switching is disabled in the standby system.
■Event history
Information on the system switching cause, the result of system switching, and the transition state of the systems (control
system and standby system) can be checked in the event history of the engineering tool.
The following items are stored in the event histories of both systems when systems are switched.
• When systems are switched due to automatic system switching: "System switching (system)" (event code: 00F00)
• When systems are switched due to manual system switching: "System switching (user)" (event code: 2B000)
For details on the event history, refer to the following.
Page 129 Event List
1 FUNCTIONS
58
1.8 Redundant Function
Name
System switching cause
Cause of system switching failure
Cause of the other system monitoring error
System switching cause (when the systems are
successfully switched)
Latest self-diagnostic error code (the other
system)
*1
Information
Result of system switching and detailed information on system switching
Result of system switching
Result and cause of system switching, transition state of the systems
Whether to set or not at the time of system switching
New control system





When system switched from the standby system to the
control system
Off  On (When system switching is enabled in standby system)
Off  Flashing (When system switching is disabled in standby system)
On  Off
Standby system
Off
On
New standby system




