Mitsubishi Electric MELSEC iQ-R Series - Page 543

35 MAINTENANCE AND INSPECTION OF A REDUNDANT SYSTEM
35.1 Module Replacement in a Redundant System
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*1 When the power supply module is redundant, only one of the two power supply modules can be replaced.
*2 A module can be replaced by turning on SM1646 (System switching by a user) to execute system switching and powering off the main
base unit in the standby system after system switching.
*3 A module supporting the online module change function can be replaced by online module change. ( MELSEC iQ-R Online Module
Change Manual)
*4 When replacing a module not supporting the online module change function, the module can be replaced by turning on SM1646
(System switching by a user) to execute system switching and powering off the main base unit in the standby system after system
switching.
• When a module is replaced after powering off the standby system, a continuation error occurs in the CPU
module of the control system. After replacing a module, clear the continuation error that has occurred in the
CPU module of the control system.
• When replacing the CPU module, if functions added or changed by the upgrade are used, replace it with a
CPU module with a firmware version that supports those functions. ( Page 747 Added and Enhanced
Functions)
■Replacement/addition of a base unit and extension cable
The following table lists base units and extension cables, and whether they can be replaced/added.
Replacement target Availability Reference
Main base unit Main base unit of the standby
system
Can be replaced by powering off the main base unit of the
standby system.
Page 546 Replacing the main
base unit
Main base unit of the control
system
Can be replaced by turning on SM1646 (System switching by a
user) to execute system switching and powering off the main
base unit in the standby system after system switching.
Extension base unit The extension base unit cannot be turned off and replaced
while the system is operating.

Extension cable Between the main base unit of
the standby system and the
extension base unit
Can be replaced by powering off the main base unit of the
standby system.
Page 547 Replacing the
extension cable between the main
base unit and extension base unit
Between the main base unit of
the control system and the
extension base unit
Can be replaced by turning on SM1646 (System switching by a
user) to execute system switching and powering off the main
base unit in the standby system after system switching.
Between extension base units Only the inactive extension cable can be replaced. If the
extension cable on the active side is disconnected, system
switching occurs, and the cable cannot be replaced.
Page 547 Replacing the
extension cable between
extension base units