Omron CJ - PROGRAMMING MANUAL 12-2009 - Power Interruptions While Accessing File Memory

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Using File Memory Section 5-3
5-3-3 Power Interruptions while Accessing File Memory
If a power interruption occurs while the CPU is accessing file memory (the
Memory Card or EM file memory) the contents of the Memory Card may not
be accurate. The file being updated may not be overwritten correctly and, in
some cases, the Memory Card itself may be damaged.
The affected file will be deleted automatically by the system the next time that
power is turned ON. The corresponding File Deletion Notification Flag
(A39507 for the Memory Card, A39506 for EM file memory) will be turned ON.
The flag will be turned OFF the next time that the power is turned OFF.
When a file is deleted, a deletion log file (DEL_FILE.IOM) will be created in
the root directory of the Memory Card or EM file memory. The deletion log file
can be read with CX-Programmer or FREAD(700) to check the following infor-
mation: The date that the file was deleted, the type of file memory (media) that
existed, the subdirectory, file name, and extension. When necessary, recreate
or recopy the deleted file.
The following diagram shows the structure of the deletion log file.
Year Month Day Extension Media
Deleted file's subdirectory
and file name (73 bytes)
Media type (2 bytes)
0000: Memory Card
0001: EM file memor
y
Deleted file's
extension
(4 bytes)
Date of file deletion
(6 bytes)
File size: 86 bytes