Mitsubishi MELSEC-A Series Reference Manual page 99

5. SPECIFICATIONS
(5) Data link when a power failure occurs to local station or remote I/O station
If the data link is disabled due to power failure at a local station or a remote I/O
station, the link loops back toward the master station, and the data link is maintained
by the normally operating stations. (The station where the power failure occurred is
disconnected from the data link.)
When the power supply to the disconnected station is turned on, the data link in the
forward loop recovers. Whether the station will remain disconnected or return to the
data link is depending on the setting of the automatic return function. (Refer to
Section 5.3.3.)
Fig 5.7 Local station or remote I/O station power failure data link
(When one master station and eight slave stations are used)
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