Mitsubishi Electric L02SCPU User's Manual And Reference page 331

(7) Clearing the file register
If the Latch (2) is set in the Device tab of the PLC parameter dialog box, the data in the file register are not
cleared even if the CPU module is powered off or reset. (Data cannot be cleared by performing a latch clear
*1
operation. )
For how to clear the data, refer to the "Latch data clear" section. ( Page 89, Section 3.4 (4))
*1 The latch range of the file register can be set in the Device tab of the PLC Parameter dialog box. ( Page 328,
Section 5.7 (6) (b))
(8) Deleting a file register file
Open the "Online Data Operation" dialog box.
[Online]  [Delete PLC Data...]
(9) Precautions
(a) If the file register number not registered is used
If a file register file is not registered and writing to or reading from the file register is performed, "OPERATION
ERROR" (error code: 4101) occurs.
(b) If writing to or reading from the file register is performed exceeding the registered
size of points
"OPERATION ERROR" (error code: 4101) occurs.
(c) File register size check
When writing to or reading from the file register, check the file register size so that data can be written or read
within the size (points) set for the CPU module. Check the file register size at step 0 in the program if any file
register is used.
Transfer
command
The file register size can be checked in SD647.
Before executing a file register block switching instruction (RSET), ensure that 1K points or more of space are
secured after the switching.
(File register size) > [32K points  (Switching block No.) + 1K points]
Block switching command
4K points specified
CHAPTER 5 DEVICES
Final file register
range check
Alarm processing
Writing to the file
register
Final file register
range check
Alarm processing
Switching to block 1
5
329