Mitsubishi Electric MELSEC Q Series Reference Manual page 268

(3) When system switching is requested from the CC-Link IE Controller Network
module (own station)
Th = 150 + Td + Tc + Tsw + (SS × 2) [ms]
Th: Cyclic data retention time
Td: Data link monitoring time
Tc: System switching monitoring time
Tsw: System switching time of Redundant CPU
SS: Sequence scan time of Redundant CPU
*1 Set it by "Network Range Assignment" of the control station. (
*2 For details, refer to the following.
QnPRHCPU User's Manual (Redundant System)
Control station
Station No.1
OFF
SB0049
1
System A CPU
scan time
Data sent from
station No.1 to 0)
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 station
0)
from station
No.1 or 2
266
*1
*1
Communication
error occurred
Communication error station
Data link
monitoring time
2 3
1)
Cyclic transmission delay time
Cyclic data retention time
*2
*2
Page 183, Section 6.3)
ON
Issue of system
switching request
System switching
monitoring time
4
Standby system
1)
Control system
System switching time
5
4)
Cyclic transmission delay time
4)
6
5)
5)