System Determination; When Both Systems Are Started Up - Mitsubishi Electric MELSEC iQ-R Series User Manual

11.6

System Determination

This section describes how the control or standby system is determined.

When both systems are started up

The control or standby system is determined as described below.
Determination method
The control or standby system is determined when both systems are started up by powering on or resetting the system and
tracking communications between the two systems are established.
■When both systems are simultaneously started up
The system A will be "control system" and the system B will be "standby system".
"Simultaneously" here means when one system is started up within three seconds of the other.
■When the system A or the system B is started up first
• In a redundant system without extension base units, the started system will enter the state that waits for the other system to
start in three seconds. ( Page 163 State that waits for the other system to start)
• In a redundant system with redundant extension base unit, when the systems are powered on or reset one by one, the
system that is started up first will be the control system and the other system will be the standby system. Settings for the
state that waits for the other system to start in the CPU parameter (Control/Standby System Start-up Setting) become
invalid.
Check method
Check the LED status of the redundant function module to check which system is the control system.
System
Control system
Standby system
Users can also check which system is the control system using the engineering tool. ( GX Works3
Operating Manual)
• System monitor
• Monitor status bar
Precautions
■If the system A/B setting has not been set or the same system A/B setting has been set
A stop error occurs. To determine the control and standby systems, properly set the system A/B setting for both systems.
■If both systems are restarted when a stop error has occurred in the standby system (system
A)
A stop error may occur in both systems.
If the stop error cause of the system A is a program error, a stop error occurs in 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 also occurs in the
system B if a file mismatch is detected in the system consistency check after the restart. As a result, a stop error occurs in
both systems.
In this case, eliminate the cause of the error that has occurred in the system A, and restart both systems.
LED status of the redundant function module
11 BASIC CONCEPT OF REDUNDANT SYSTEM
11.6 System Determination
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