Mitsubishi Electric QJ71E71-100 User Manual page 348

(5) System switching time of a redundant system
The following shows the system switching time required when the E71 mounted with the control system CPU
module in a redundant system issues a system switching request to the control system CPU module at
communication error or disconnection detection. The system switching time is the time from when a
communication error or disconnection is detected until the control system CPU module is switched to the standby
system CPU module.
(a) When a communication error is detected
• For alive check errors
Tnc = Tsi + Ti × Tr + St + Tsw
• Tnc
• Tsi
• Ti
• Tr
• St
• Tsw
The following shows the timing for system switching operation if an alive check error occurs.
QJ71E71-100
Station No.1
QJ71E71-100 (station No.1)
Scan time of the system A CPU
Scan time of the system B CPU
QJ71E71-100 (station No.2)
*1 For details on CPU system switching time, refer to the following.
QnPRHCPU User's Manual (Redundant System)
346
: System switching time
: Destination existence confirmation starting interval timer value
: Timer value of the alive check
: Destination existence confirmation resending time
: One scan time
:
CPU system switching time
A communication
error occurred.
Control system (system A)
Tracking cable
System switching
request
Communications have not been performed with
the connected device for a fixed period.
Operating as a control system
Tsi
System A Control system
System B Standby system
Operating as a standby system
*1
Connected device
Standby system (system B)
(Tr = 3)
Operating as
a standby system
Ti Ti Ti
Issuing a system
switching request
Standby system
Tsw
Tnc
QJ71E71-100
Station No.2
Control system
Operating as
a control system