Mitsubishi Electric MELSEC-Q00U(J)CPU User Manual page 288

(d) Operating procedure (when a CPU stop error has occurred)
The data is automatically backed up when a CPU stop error has occurred.
1.
To specify the upper limit value of the number of backup data, set the upper limit value setting.
(The setting method and operating procedure are the same as the backup by turning on SM1926.)
Page 283, Section 3.32.1 (2) (a))
2.
To retry the automatic backup, turn on bit10 of SD910 (Backup function setting). For the retry of
the automatic backup, refer to the following.
Page 284, Section 3.32.1 (3) (a)
3.
Turn on bit15 of SD910.
Remark
The automatic backup may not be able to be performed when a major error has occurred.
(4) Checking errors
Even when an error has occurred, a diagnostic error is not detected. In that case, the error code is stored in
SD916 (Cause of error occurred during backup). (
and Inspection))
(5) Precautions
The following describes precautions for the backup function.
(a) Removal/insertion of the SD memory card and power-off/reset of the CPU module
during the backup
Do not perform the following operations during the backup operation.
• Removal and insertion of the SD memory card
• Power-off or reset of the CPU module
If performed, the backup data in the SD memory card is left in an incomplete state, which is middle of the
backup processing. Do not use these data for a restoration. If these data are used, the restoration is completed
with an error.
(b) Suspending processing of the backup
The following operations can suspend the processing of the backup.
• To disable the SD memory card operation forcibly
• To enable removal and insertion of the SD memory card
If the backup processing is suspended, the backup data in the SD memory card is left in an incomplete state,
which is middle of the backup processing. Do not use these data for a restoration. If these data are used, the
restoration is completed with an error.
(c) Changing device data
Do not make the device data change during the execution of backup. Since the device data is backed up
separately into multiple scans, the data inconsistency is occurred if the device data is changed.
(d) Changing backup target data
Do not change the backup target data in the CPU module during backup. If the target data are changed, the
change is not reflected.
(e) Required time for backup
According to the data size or number of files stored in a CPU module, a backup may take time.
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QCPU User's Manual (Hardware Design, Maintenance