Mitsubishi Electric Q80BD-J71GP21-SX User Manual page 222

APPENDICES
(4) Automatic switching of communication path
App
- 5 Appendix 1 Precautions for Accessing Redundant CPU System
When a communication error occurs during access to the Redundant CPU connected
via MELSECNET/H, the communication path is automatically switched to continue
access to the control system.
Hereinafter, this automatic switching of the communication path is referred to as path
switching.
The following describes the path switching conditions, checking method of path
switching occurrence, and access examples of path switching.
(a) Path switching conditions
When access is being processed under the following conditions, access to the
Redundant CPU is continued by path switching even though a communication
error occurs.
Operation mode
Redundant CPU
specification
Note, however, that if a tracking error
communication, access to the control system is not continued by path switching
even if tracking is recovered after that.
*1: Includes the status in which either Redundant CPU is powered OFF or reset.
Conditions for continued access
Backup mode, Separate mode
Control system, Standby system, System A, System B
*1
had already occurred at a start of