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MELSEC-Q
1 OVERVIEW
(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 (in 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 (in the 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, which stops the CPU module, occurs during system operation.
(e) The time of transient error occurrence can be checked.
(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 executable for the Q series I/O modules and
modules of function version C and later, such as analog-to-digital converter
modules, digital-to-analog converter modules, channel isolated
thermocouple input modules, and temperature control modules.
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.
(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 access from the
outside via an Ethernet interface module or serial communication module.
(Remote password)