4
FUNCTIONS
4.3 RAS Functions
4.3.2 Loopback function
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4.3.2
Loopback function
This function isolates a disconnected cable or faulty station from the network, so that data
link can be continued among normally operating stations.
(1) Cable disconnection
Data link is continued even if a cable is disconnected.
POINT
Although the CC-Link IE controller network uses 2 core cables, loopbback occurs
even if a disconnection or an error is detected on one side. (Transmissions using
one side only are not performed.)
(2) Station failure
Data link is continued except for a faulty station.
If two or more stations go down, a station located between the faulty stations cannot
perform data link.
However, when more than one station exist between the faulty stations, a normal
station is changed to a sub-control station and continues data link.
Figure 4.49 Cable disconnection
Figure 4.50 Station failure
Control station
No.1
Normal station
No.6
Normal station
No.5
Normal station
No.4
Normal station
No.2
Normal station
No.3
Disconnection
Control station
No.1
Loopback station
Normal station
No.6
Loopback station
Normal station
No.2
Normal station
No.5
Sub-control station
No.3
Loopback station
Normal station
No.4
Loopback station
Down
Down
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