Mitsubishi Electric MELSEC iQ-R Series User Manual page 56

■System switching due to moderate error or major error
When either a moderate or major error occurs in the remote head module of the control system, the remote head module of
the standby system switches to the control system. The remote head module of the control system where the moderate or
major error has occurred switches to the standby system.
However, depending on the content of the major error, the remote head module of the control system may not switch to the
standby system.
(1)
(4)
(2) (3)
(1) Master station
(2) Control system  New standby system
(3) Standby system  New control system
(4) System switching (A moderate or major error has occurred in the control system.)
■System switching due to data link error
When the data link of the remote head module of the control system continues to be in an error state (D LINK LED is either off
or flashes) for the system switching monitoring time set in the master station or longer, the remote head module of the standby
system switches to the control system. The remote head module of the control system where the data link error has occurred
switches to the standby system.
(1)
(4)
(2) (3)
(1) Master station
(2) Control system  New standby system
(3) Standby system  New control system
(4) System switching (The data link continues to be in an error state for the system switching monitoring time or longer.)
System switching does not occur if a data link error occurs due to any of following at power-on.
• No Ethernet cable is connected to the remote head module of the control system.
• An Ethernet cable connected to the remote head module of the control system is disconnected.
■System switching operation from the engineering tool
For how to operate engineering tools, refer to the following.
 GX Works3 Operating Manual
The system switching operation using the engineering tool can be performed only from the remote head module of the control
system.
Also, to perform system switching operation using the engineering tool, 'System switching by a user' (SM1646) must be kept
on (permitting manual switching) beforehand.
1 FUNCTIONS
54
1.8 Redundant Function