Mitsubishi Electric Melsec QJ71LP21 Reference Manual page 378

7 APPLICATION FUNCTIONS
Station No. 1 Control station
System A CPU
scan time
Data sent from
station No. 1 to
other station
System A
Control system
Standby system
System B
Station No. 2
Normal station
System B
CPU scan time
Data sent from station
No. 2 to other station
Other station's data
received from
station No. 1 or 2
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(1) Cyclic data retention time for control system power supply module
malfunction, power supply off, control system CPU malfunction, or
resetting
Use the following expression to calculate the cyclic data retention time in the
case of control system power supply module malfunction, power supply off,
control system CPU malfunction, or resetting.
(a) When the redundant system has a control station
1) Redundant CPU system switching time (Tsw) < Control station shift time
(Csw)
[Cyclic data retention time (T
T Csw+SS [ms]
H=
Csw : Control station shift time [ms]
SS : Redundant CPU scan time [ms]
Communication error station
Power
supply down
1
0) 1)
Standby system
System switching time
Cyclic transmission
delay time
0)
)]
H
Control system
Control station shift time
2 3
1)
Cyclic data retention time
Sub control station
4 5
3) 4)
Cyclic transmission delay time
3) 4)
MELSEC-Q
6
5) 6)
5)
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