System Switching Request To The Control System Cpu - Mitsubishi Electric Q Series Reference Manual

7 APPLICATION FUNCTIONS

7.10.5 System switching request to the control system CPU

System switching
request
Control system
(system A)
Control
station
(station
Redundant
No. 1)
CPU
A communication
error occurs.
Tracking cable
Normal
Q25H station
CPU (station
No. 4)
Station No. 1
Monitoring time
SB0049 OFF
System switching
monitoring time
(SW0018)
System A
System B
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The network module in the control system of the redundant system automatically
issues a system switching request to the control system CPU when the data link status
of the network module remains faulty (the D. LINK LED goes off) over the system
switching monitoring time (the time set at SW0018).
Standby system
(system B)
Normal
Redundant station
(station
CPU
No. 2)
Normal
Q25H station
CPU (station
No. 3)
(1) Process for issuing a system switching request
1) An error occurs in the network module mounted to the control system CPU.
2) After the monitoring time has elapsed, the D. LINK LED goes off (the host
station data link status (SB0049) is ON).
3) After the time set for the switching monitoring time setting (SW0018) has
elapsed, a system switching request is issued to the control system CPU.
4) Upon receipt of the system switching request from the network module, the
control system CPU switches the systems.
5) After system switching has been completed, the network module mounted to
the new control system CPU continues a data link.
A communication
error occurs.
Control
Communication error station
station
Monitoring time
Control system
Standby system
Standby system
(system A)
Redundant
CPU
Q25H
CPU
ON
A system switching
request is issued.
System switching
monitoring time
Standby system
Control system
MELSEC-Q
Control system
(system B)
Control
Redundant
station
CPU
(station
No. 1)
Tracking cable
Normal
station
Q25H
(station CPU
No. 4)
Normal
station
(station
No. 2)
Sub control
station
(station
No. 3)
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