Mitsubishi Electric MELSEC Q Series Reference Manual page 265

(b) When a redundant system is the control station and "System switching time of
Redundant CPU (Tsw) > Control station switching time (Csw)" is met
Th = Tsw + SS × 2 [ms]
Th: Cyclic data retention time
Tsw: System switching time of Redundant CPU
Csw: Control station switching time = 20 + Constant link scan set value (
SS: Sequence scan time of Redundant CPU
*1 For details, refer to the following.
QnPRHCPU User's Manual (Redundant System)
Station No.1 Control station
System A 1
CPU scan time
Data sent from
0)
station No.1 to
another station
Control system
System A
System B Standby system
Normal station
Station No.2
System B
CPU scan time
Data sent from
station No.2 to
another station
Data received
at another
0)
station from
station No.1 or 2
*1
*1
Communication error station
Power
down
1)
Standby system
System switching time
Sub-control station
Control station switching time
Cyclic transmission delay time
1)
Cyclic data retention time
CHAPTER 7 PROCESSING TIME
Page 201, Section 6.3.6 (1))
Control system
3
4
2
1)
2) 3)
Cyclic transmission delay time
2)
7
5
4)
3)
4)
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