Determining Control System And Standby System - Mitsubishi Electric MELSEC iQ-R Series User Manual

Determining control system and standby system

The control system and standby system of the remote head modules are determined either in order of system power supply
startup or remote head module reset clear.
Single line
This section describes the system determination for when the remote head module is redundant with single line and
redundant slave station.
After the system starts, the CTRL LED of the remote head module of the control system and the SBY LED of the remote head
module of the standby system turn on.
■When the system starts by turning the power on
Remote head No.1 will be the control system and remote head No.2 will be the standby system.
• When remote head No.2 is the control system and the power is turned off and on, remote head No.1
switches to the control system and remote head No.2 switches to the standby system.
• When only remote head No.1 is mounted or remote head No.2 has failed, remote head No.1 will be the
control system.
• When only remote head No.2 is mounted or remote head No.1 has failed, the system does not start. To start
the system, remote head No.1 must be replaced, or remote head No.2 must be mounted in the CPU slot.
■When the system starts by resetting the remote head module of the control system
Only the remote head module of the control system is reset, and system switching occurs.
After reset clear, the reset remote head module will be the standby system.
• When only remote head No.1 is mounted or remote head No.2 has failed, the entire system is reset.
• When remote head No.2 is reset and remote head No.1 has failed, the entire system is reset. However,
after reset clear, the system does not start. To start the system, remote head No.1 must be replaced, or
remote head No.2 must be mounted in the CPU slot.
■When the system starts by resetting the remote head module of the standby system
Only the remote head module of the standby system is reset.
After reset clear, the reset remote head module will be the standby system.
■When the system starts by simultaneously resetting the remote head modules of both
systems or by performing remote reset operation
The entire system is reset.
After reset clear, remote head No.1 will be the control system, and remote head No.2 will be the standby system.
Remote reset operation can be performed only on the remote head module of the control system.
■When the system starts after the remote head module of the standby system is replaced
The replaced remote head module will be the standby system.
The remote head module of the control system will remain as the control system.
Replacement of the remote head module can be performed only on the remote head module of the standby
system.
For the replacement procedure, refer to the following.
Page 100 For the standby system in a redundant system configuration
1 FUNCTIONS
48
1.8 Redundant Function