Mitsubishi Electric MELSEC iQ-R Series User Manual page 166

Operation when the control or standby system has not been determined yet
In a redundant system without extension base units, the operation of the CPU module is the same as that in the state that
waits for the other system to start (refresh operations to be performed while the CPU module is in the state that waits for the
other system to start). ( Page 163 Operation of the CPU module in the state that waits for the other system to start)
The following tables list the refresh operations in a redundant system with redundant extension base unit.
■Refresh for the modules mounted on the main base unit
Type
I/O refresh
Network module link refresh
Intelligent function module refresh
■Refresh for the modules mounted on an extension base unit
Type
I/O refresh
Network module link refresh
Intelligent function module refresh
Precautions
• To start up the system that is waiting for the other system to start as the control system, check that the other system is not
operating as the control system.
• When tracking communications are established by connecting tracking cables and powering on or resetting the other
system, the CPU module that has been waiting for the other system to start enters the RUN state and starts executing
programs. For this reason, check that program execution by the CPU module does not cause any problems before
connecting tracking cables and starting up the other system.
• If a stop error has occurred in the other system when tracking communications are established between the two systems, a
stop error occurs in the CPU module that has been waiting for the other system to start as well. In this case, take action
against the error of the other system, and power off and on or reset both systems.
• When tracking communications cannot be established due to power-off of the other system or a problem with tracking
cables, the CPU module enters the state that waits for the other system to start. Check that the other system is powered on
and there is no problem with tracking cables. ( Page 537 When the L ERR LED turns on)
• Do not power off or reset the CPU module, or remove an SD memory card during an access to the SD memory card. (
Page 162 When an SD memory card is used)
• To start up the systems one by one in a redundant system with redundant extension base unit, complete the start-up
process of one system first. Then, start up the other system. ( Page 57 Starting up the systems one by one) During
start-up of a system, the system cannot perform tracking communications. For this reason, a stop error may occur in the
CPU module of the system that is started up later. In this case, restart the system having the CPU module in which a stop
error has occurred. (When automatic recovery is set, the system can be automatically restarted.) ( Page 430 Automatic
recovery of the CPU module of the standby system)
11 BASIC CONCEPT OF REDUNDANT SYSTEM
164
11.6 System Determination
Operation
Only the input refresh is performed. The output refresh is not performed.
Between the network module and the CPU module, SB/SW is refreshed but other link devices
are not.
Data is refreshed between the intelligent function module and the CPU module.
Operation
Neither the input nor output refresh is performed.
Data is not refreshed between the network module and the CPU module.
Data is not refreshed between the intelligent function module and the CPU module.