Mitsubishi MELSEC-A Series Reference Manual page 98

5. SPECIFICATIONS
(4) Data link when both the forward and reverse loops are faulty
When a fault occurs to the cables of forward and reverse loops and the cable
connecting connector, the link loops back toward the master station in front of faulty
station, and data link is maintained by the normally operating. (Faulty stations are all
disconnected.)
When the faulty part is returned to normal, the data link in the forward loop is
recovered. Whether the station will remain disconnected or return to the data link
depending on the setting of the automatic return function. (Refer to Section 5.3.3.)
Fig 5.6 Data link when forward/reverse loop is faulty
(When one master station and eight slave stations are used)
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