Mitsubishi QJ71LP21 Reference Manual page 22

1 OVERVIEW
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(4) Enhanced RAS functions (Refer to Section 3.2.2 "RAS functions")
(a) When a faulty station recovers and can resume normal operation, it
automatically returns to the network to resume the data communication
using the automatic return function.
(b) By using the loopback function (the optical loop system), it is possible to
continue data transmission among operational stations by disconnecting
faulty areas such as a part of the network where there is a cable
disconnection, a faulty station, etc.
(c) By using the station detach function (coaxial 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.
(d) The network module can continue the transient transmission even if an error
that stops the CPU module while the system is operating occurs.
(e) It is possible to check the time when a transient error occurred.
(f) By mounting 2 power supply modules on a remote I/O station, either of
them can be replaced without powering off the station. (Redundant power
supply on remote I/O station)
The redundant power supply base unit is required for mounting 2 power
supply modules.
(g) When an input module, an output module or an intelligent function module
mounted on a remote I/O station fails, the faulty module can be replaced
without stopping the system operation. (Online module change)
Online module change is available for Q series I/O modules and function
version D or later analog-to-digital and digital-to-analog converter modules,
temperature input modules and temperature control modules.
REMARK
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.
(5) Control of external connection to remote I/O stations (refer to
Section 7.12)
Setting a remote password for a remote I/O station restricts connections from the
outside via an Ethernet interface module or serial communication module.
(Remote password)
MELSEC-Q
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