Mitsubishi Electric MELSEC Q Series Reference Manual page 30

(4) Enhanced RAS functions
(a) Continuation of communications at system down of the control station
Even if the control station goes down, a normal station (sub-control station) will take over the control to
continue data link. (
(b) Disconnection of a faulty cable and station
Any disconnected cable or faulty station can be isolated from the network, and data link can be continued
among normally operating stations. (
(c) When a disconnected station recovers from an error, the station is automatically
reconnected to the network
When a station disconnected from a network due to a data link error recovers from the error, the station is
automatically reconnected to the network and restarts data link. (
This automatic return does not affect data link.
Control station
No.1
Normal station
No.4
28
Page 124, Section 4.4.1)
Control station
No.1
Down
Normal station
No.4
Control station Normal station
No.1 No.2
Loopback station
Normal station
No.6
Normal station
Loopback station
No.5
Normal station
No.2
When recovered
from fault
Normal station
No.3
Down
Switching
Sub-control station
No.2
Normal station
No.3
Page 125, Section 4.4.2)
Sub-control station
No.3
Down
Loopback station
Down Normal station
No.4
Loopback station
Control station
No.1
Normal station
No.4
Page 127, Section 4.4.3)
Normal station
No.2
Normal station
No.3
Reconnected