Mitsubishi Electric MELSEC Q Series Reference Manual page 267

(2) When a stop error occurs in the control system CPU, System switching
instruction is executed, system switching is executed from the programming
tool, or system switching is requested from another network module
Th = Tsw + SS [ms]
Th: Cyclic data retention time
Tsw: System switching time of Redundant CPU
SS: Sequence scan time of Redundant CPU
*1 For details, refer to the following.
QnPRHCPU User's Manual (Redundant System)
Execution of system
switching instruction
1
System A
CPU scan time
Data sent from
0)
station No.1 to
another station
Control system
System A
System B Standby system
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
2
1)
Standby system
Control system
System switching time
Cyclic transmission
Cyclic transmission delay time
delay time
1)
Cyclic data retention time
CHAPTER 7 PROCESSING TIME
4
3
2) 3)
3)
2)
7
5
4)
4)
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