System Switching Time In Redundant System - Mitsubishi Electric Melsec Q Series User Manual

3
SPECIFICATIONS

3.5.3 System switching time in redundant system

This is the time taken from when the control system QJ71PB92V sends a system
switching request to the redundant CPU until control is started with another QJ71PB92V in
a new control system.
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- 65 3.5 Processing Time
3.5.3 System switching time in redundant system
System A
QJ71PB92V
Control system
System switching
request
New standby system
Figure 3.41 System Switching Time in Redundant System (When QJ71PB92V Requests System
(a) Redundant system switching time calculation formula
The system switching time in the redundant system can be obtained from either of
the following calculation formulas:
• When the systems are not switched due to a slave error, or when the system
switching condition (Un\G23648) is set to OR, the system switching time
(Tscu) is:
Tscu [ms] = TcpuA + Tsw + Tp + Scan
• When the system switching condition (Un\G23648) is set to AND, the system
switching time (Tsca) is:
Tsca [ms] = Tscu + Nand
System A System B
Redundant CPU Redundant CPU
Control system Standby system
System switching
TcpuA
request
System switching
New standby system New control system
Switching to Redundant CPU)
20
System B
QJ71PB92V
Standby system
Tsw
Tp
request
New control system
2
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