Mitsubishi Electric MELSEC Q Series Reference Manual page 141

(2) Data link continuation
If an error occurs in the control system CPU or CC-Link IE Controller Network module, the control and standby
systems will be switched each other and the former standby system takes over the system control and continues
data link.
Control
station No.3
Control
system
Communication
error
Control
station No.3
Standby
system
Communication
error
Remark
There are the following two kinds of system switching.
● Switching by the system
• When a fault occurs in the control system
• Switching request from a network module
● Switching by the user
• System switching operation from a programming tool
• System switching instruction
For details, refer to the following.
QnPRHCPU User's Manual (Redundant System)
Normal
station No.4
CC-Link IE Controller Network
Disconnected Standby
station No.1 system
Tracking cable
Communication error
occurred on control system.
Normal
station No.4
CC-Link IE Controller Network
Control
Disconnected
system
station No.1
System switched
Tracking cable
Normal
station No.2
Normal station on new control
Normal
system continues data link.
station No.2
CHAPTER 4 FUNCTIONS
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