Mitsubishi Electric MELSEC iQ-R-R00CPU User Manual page 620

■Special relay
The following table shows the special relay for system switching and the storage status of the CPU modules in the control
system and standby system.
: Stored, : Not stored
SM Name
number
SM1637 System switching detection (standby system to control system)
SM1643 ON for only one scan after system switching (standby system to control system)
SM1644 ON for only one scan after system switching (control system to standby system)
SM1645 System switching request from a network module
SM1646 System switching by a user
■Special register
The following table shows the special register for system switching and the storage status of the CPU modules in the control
system and standby system.
: Stored, : Not stored
SD Name
number
SD1642 BACKUP/SEPARATE LED flashing cause
SD1643 System switching cause
SD1644 Cause of system switching failure
SD1645 System switching request status from a network module of own system
SD1646 System switching request status from a network module of the other system
SD1648 Cause of the other system monitoring error
SD1649 System switching cause (when the systems are successfully switched)
SD1650 System switching instruction ID number
*1 When the system switching has not been normally completed, a value is stored in this special register area of the control system.
CTRL LED and SBY LED of the redundant function module
System switching results can be checked with the CTRL LED and SBY LED on the front of the redundant function module.
Switching from the standby system to the control system
37 FUNCTIONS
618
37.1 System Switching
*1
Switching from the control system to the standby system
Storage status at system switching
New control system New standby system
CPU module CPU module
 
 
 
 
 
Storage status at system switching
New control system New standby system
CPU module CPU module
 
 
 
 
 
 
 
 