Mitsubishi Electric MELSEC-Q00U(J)CPU User Manual page 257

*1 The data are backed up only when the file register in the standard RAM is used and the following parameter is set.
• CPU modules other than the High-speed Universal model QCPU and Universal model Process CPU: Check the
"Transfer to Standard ROM at Latch data backup operation" checkbox on the PLC file tab. (
Appendix 1.2.3)
• High-speed Universal model QCPU and Universal model Process CPU: Check the "Backup all files in the internal
of standard RAM" checkbox on the PLC system tab. (
*2 The data are backed up only when the Universal model QCPU whose serial number (first five digits) is "10042" or later is
used.
*3 The data are backed up regardless of the setting status of the module error collection function.
*4 The data are backed up regardless of the existence of files in the standard RAM if the "Backup all files in the internal of
standard RAM" checkbox is checked on the PLC system tab.
*5 Only the High-speed Universal model QCPU and Universal model Process CPU back up these data.
*6 A storage file is created only when the trace registration has been made. The data are not backed up in the following
cases.
• Trace settings are stored in a memory card.
• Trace settings are not written to the CPU module.
*7 These are sizes when the device assignment is default. Sizes differ depending on parameter settings.
(2) Execution using a contact
(a) Setting method
Check the "Execute by contact" checkbox and set a contact for the latch data backup operation in the PLC
system tab of the PLC parameter dialog box. (Devices X, M, or B can be selected.)
Check this checkbox
and set a contact.
(b) Execution method
Backup starts at the rise of a contact (off  on).
After the backup operation is completed, the BAT.LED of the CPU module flashes (green). The module is in the
standby status and is ready to be powered off.
(c) Precautions
• Backup data are the data when the contact is on (END processing). To run the CPU module again after the
backup operation, power on or reset the CPU module.
• Since the status of the contact is checked during execution of the END instruction, data are not backed up
even if the contact is turned on  off  on, or off  on off within one scan.
• In the following cases, data are not backed up unless the contact is turned off and then on.
• The device X is set as a contact, the backup operation is performed by turning off and then
on the contact, and the CPU module is powered off and then on or is reset without turning
off the contact.
• The device M or B is set as a contact and the backup operation is performed by turning off
and then on the contact.
CHAPTER 3 FUNCTIONS
Page 438, Appendix 1.2.2)
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