Chapter 10 Online Module Change; Precautions On Online Module Change - Mitsubishi Electric MELSEC-Q series User Manual

CHAPTER 10
This chapter describes the online module change procedure. In this manual, the procedure is explained using GX
Works2
When performing an online module change, carefully read the following.
• QCPU User's Manual (Hardware Design, Maintenance and Inspection)
10.1

Precautions on Online Module Change

This section lists precautions on an online module change.
• Always perform an online module change in the correct procedure (
to do so can cause a malfunction or failure.
• Perform an online module change after making sure that the system outside the programmable controller will
not malfunction.
• Provide means such as switches for powering off each of the external power supply and external devices
connected to the module to be replaced online. Failure to do so may cause an electric shock and
malfunction of operating modules.
• After the module has failed, the buffer memory data may not be saved properly. Prerecord the data to be
saved.
• It is recommended to perform an online module change in the actual system in advance to ensure that it
would not affect the other modules. For the operational verification, check the following:
• Means of cutting off the connection to external devices and its configuration are correct.
• Switching on/off does not bring any undesirable effect.
• After the first use of the product, do not mount/remove the module to/from the base unit, and the terminal
block to/from the module more than 50 times (IEC 61131-2 compliant) respectively. Exceeding the limit may
cause malfunction.
Dedicated instructions cannot be executed during an online module change. Save and restore the offset/gain setting values
in the user range using a dedicated instruction in another system.
Precautions for using other systems are as follows:
• To change a module mounted on the remote I/O station online, save and restore the offset/gain setting values in
the user range using a dedicated instruction, in another system mounted on the main base unit.
• The offset/gain setting values cannot be saved and restored using a dedicated instruction in another system
mounted on the remote I/O station.
If no other systems are available, restore the values by writing them to the buffer memory.
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ONLINE MODULE CHANGE
Page 183, Section 10.4). A failure