Function For Returning To Control Station In A Redundant System - Mitsubishi Electric Melsec QJ71LP21 Reference Manual

7 APPLICATION FUNCTIONS

7.10.6 Function for returning to control station in a redundant system

1) When the control station falls into a communication error,
another normal station will become a sub control station.
Control system
Standby system
(system A)
Control
station
Redundant
(station
CPU
No. 1)
A communication
error occurs.
Normal
Q25H station
CPU (station
No. 4)
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This section describes unavailability of the function for returning to control station
status when a redundant system has been acting as a control station.
In the redundant system, when the redundant CPU is in the standby system at the time
of return to the system, the previous control station is returned as a normal station
even if "Return as control station" is set for the return setting for the station.
Standby system
Control system
(system B)
Redundant
CPU
Q25H
Sub control
CPU
2) System switching does not occur even if station No. 1 returns to the
system, and system A remains as the standby system and returns as
a normal station (it does not return as a control station).
Standby system
(system A)
Normal
station Redundant
CPU
(station
No. 2)
Normal
station
Q25H
CPU
station
(station
No. 3)
MELSEC-Q
Control system
(system B)
Normal
station Redundant
(station
No. 1)
Normal
station
(station
No. 4)
Normal
station
(station
CPU
No. 2)
Sub control
Q25H
station
CPU
(station
No. 3)
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