Precautions For Replacement Procedures - Mitsubishi Electric MELSEC iQ-R Series Manual

3.3

Precautions for Replacement Procedures

• Before online module change, make sure that the systems outside the programmable controllers are free from malfunction.
• The precautions for mounting and removing a module are the same as the ones for mounting and removing a module on
and from a base unit. ( MELSEC iQ-R Module Configuration Manual)
• For the precautions for operation and wiring of a module to be replaced, refer to the user's manual of each module.
• Changing a module directly during module access causes the module access to be interrupted. For example, performing
online module change while the FROM instruction is in execution causes incomplete data retrieval. After the online module
change is completed, execute the instruction again.
• With a module verification error occurring in direct change, one more verification error in another module is not recorded in
the error history.
• When logging is in progress on a module access device, performing online module change on the logging target module
yields a logged value of -1 during the module change. After the online module change is completed, the correct values are
logged again.
• If the systems are switched while the remote head module is being changed online, the change continues on the new
control system after the system switching. However, an error occurs on the new standby system. Reset it after the online
module change.
3 REPLACEMENT PROCEDURE
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3.3 Precautions for Replacement Procedures