Mitsubishi Electric Melsec QJ71LP21 Reference Manual page 30

1 OVERVIEW
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(f) By using the station detach function (coaxial bus system and twisted bus
system), even when some of the connected stations are down due to power
off, etc., the normal communication can be continued among other
operational stations.
(g) When an error occurs in a normal network due to disconnection, etc. the
data link can be continued by switching to link data refresh on the standby
network if two network modules, a regular module and a standby module,
are installed for each programmable controller CPU (High Performance
model QCPU and Process CPU)
(h) The network module can continue the transient transmission even if an
error that stops the CPU module while the system is operating occurs.
(i) It is possible to check the time when a transient error occurred.
REMARKS
The following faults make the RAS functions valid.
 Break in cable
 Power-off of slave station
 Network setting error
 Fault detectable by self-diagnostics of CPU module
If the network module has become faulty, the RAS functions may not be activated
depending on the fault.
MELSEC-Q
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