Mitsubishi Electric QJ71E71-100 User Manual page 217

(b) System switching request operation
The E71 monitors communications with the connected device for an error using the alive check function and
TCP ULP timer.
Connected device
Normal
communications
Control system (system A)
Tracking cable
A communication
error occurred.
Control system (system A)
Tracking cable
System switching request
Connected device
Normal
communications
Control system (system A)
Tracking cable
Standby system (system B)
Connected device
Standby system (system B)
Standby system (system B)
1.
During normal communications
The system A is operating as a control system, and the
system B as a standby system.
The connected device is communicating with the E71
mounted with the control system CPU module. (By
connecting the connected device to the E71 mounted
with the standby system CPU module in TCP/IP, an
error in the standby system CPU module can be
detected.)
2.
*1
At error detection
If a communication error has occurred between the
connected device and the E71, and the E71 mounted
with the control system CPU module detects an error, a
system switching request is issued to the control system
*2
CPU module.
3.
After system switching
The system A operates as a standby system, and the
system B as a control system.
The connected device changes the destination and
communicates with the E71 mounted with the control
system CPU module (system B).
CHAPTER 14 OTHER FUNCTIONS
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