Determination Of Control System/Standby System; When Starting Up Both Systems Simultaneously - Mitsubishi Electric MELSEC iQ-R-R00CPU User Manual

26.7

Determination of Control System/Standby System

This section describes how to determine which system is the control system and the other is the standby system.

When starting up both systems simultaneously

The following describes the method of determining the system types of when both systems are started up simultaneously.
How to determine the system types
A control system or standby system is determined when both the systems are powered off and on or the CPU module is reset
and then ready for tracking communications.
■When both systems are started up simultaneously
When both systems are started up simultaneously, the system A operates as the control system and the system B as the
standby system.
"Simultaneously" here means that one CPU module is started up within three seconds after the other CPU module is started.
■When one of the system A and system B is started up first
When one of the systems is started up first, the system will wait for the start-up of the other system in three seconds. (
Page 412 The system waiting for the start-up of the other system)
When communications for both systems are established, system A operates as the control system and system B as the
system B.
Check method
Check the LED of each redundant function module to check the status of the control system/standby system.
System status
Control system
Standby system
Users can check the status of the control system/standby system with the engineering tool. ( GX Works3
Operating Manual)
• System monitor
• Monitor status bar
Precautions
■If the system A/B settings have not been set for both systems or the same system setting has
been set for both systems
If the system A/B settings have not been set for both systems or the same system setting has been set for both systems, a
stop error occurs. To determine the control system and standby system, properly set the system A/B settings for both
systems.
■If both systems are restarted when a stop error has occurred on the standby system (system
A)
If both systems are restarted simultaneously in a system where the system A operates as the standby system due to a stop
error and the system B normally operates as the control system, a stop error may occur on both systems.
If the stop error cause of the system A is a program error, a stop error occurs on the system A again after the systems are
restarted. Even if the system B normally operates as the control system before the restart, a stop error occurs on the system
B if a mismatch between files is detected in the system consistency check after the restart. As a result, a stop error occurs on
both systems.
In this case, eliminate the cause of the error that has occurred on the system A and reset and restore both systems.
26 BASIC CONCEPT
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26.7 Determination of Control System/Standby System
LED of the redundant function module