Omron CJ2 CPU UNIT SOFTWARE User Manual page 258

7 File Operations
Accessing the Memory Card
• Never turn OFF the power supply to the CPU Unit when the BUSY indicator is lit (i.e., indicator show-
ing that the Memory Card is being accessed). The Memory Card may become unusable if this is
done.
• Never remove the Memory Card from the CPU Unit when the BUSY indicator is lit. Press the Memory
Card power OFF button and wait for the BUSY indicator to go out before removing the Memory Card.
The Memory Card may become unusable if this is not done.
• A few seconds will be required for the CPU Unit to recognize the Memory Card after it is inserted.
When accessing a Memory Card immediately after turning ON the power supply or inserting the
Memory Card, program an NC condition for the Memory Card Recognized Flag (A343.15) as an input
condition, as shown below.
Execution
A343.15
condition
Memory
Card
Detected
Flag
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 (A395.06 for the Memory Card, A395.07 for EM file mem-
ory) 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 (DELETE.TMP) will be created in the root directory of the
Memory Card or EM file memory. The deletion log file can be read with a binary editor to check the fol-
lowing information: 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
Date of file
deletion
(6 bytes)
7-6
A343.13
FREAD
File Memory
C
Operation
Flag
S1
S2
D
File size: 86 bytes
Extension
Media
Deleted file's
extension
(4 bytes)
Media type (2 bytes)
0000 hex: Memory Card
0001 hex: EM file memory
00
Deleted file's
subdirectory and file
name (73 bytes)
CJ2 CPU Unit Software User's Manual