Mitsubishi Electric MELSEC Q Series Reference Manual page 244

(e) When a transmission passes through a redundant system
Station No.3
Station No.1 Station
No.1
Control system
1.
Set a control system station as a relay station.
2.
If a system switching has occurred, change the relay station setting to a new control system
station.
Use the RTWRITE instruction to change routing parameters.
For details on the RTWRITE instruction, refer to the following.
Programming Manual (Common Instructions) for the CPU module used.
Program example of the RTWRITE instruction
Ex.
Passing through station No.2 of network No.2
Passing through station No.1 of network No.2
242
Routing parameter 1.
Relay
Target
Network No.
Network No.
1 2
Network No.2
Station No.2 Station
Standby system No.2
Network No.1
Station
No.3
Station No.3
Relay
Station No.
1
Station No.1
Standby system
Communication
error
Changed by RTWRITE
instruction.
Routing parameter 2.
Relay
Target
Network No. Network No.
1 2
Network No.2
Station Station No.2
No.1
Control system
Network No.1
Station
No.3
Relay station network No.2
Relay station No.2
Setting a dummy
Target network No.1
Relay station network No.2
Relay station No.1
Setting a dummy
Target network No.1
Relay
Station No.
1 2
Station
No.2