File Handling Precautions - Mitsubishi QCPU (Q Mode) User Manual

6 HIGH PERFORMANCE MODEL QCPU FILES

6.9.2 File handling precautions

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(1) Power OFF (or reset) during program operation
(a) If power is switched OFF during a file operation which will not cause a file
shift, the memory data will not be lost.
(b) If files and data in the memory of the High Performance model QCPU is
backed up using the battery (Q6BAT), the program memory data will not be
lost when the power is switched OFF during the following file operations
which cause a file shift.
• File size change
• PLC memory arrangement
• New file creation
• Writing a program file during the RUN status
• Writing a program in excess of memory allocated for 'Write during RUN'
• Reading a file with the PLOAD instruction
Files stored in the memory card will not be lost unless the memory card is
removed from the High Performance model QCPU while the power is OFF.
POINT
If the above operations are done, the half-processed data will be stored in the High
Performance model QCPU internal memory, and will be restored when power is
switched ON again. A battery backup is required in order to save internal memory
data for this reason.
(2) Simultaneous access of a single file from multiple GX Developers
The High Performance model QCPU permits access to a single file from a single
GX Developer. When access to the same file is made from multiple GX
Developers, the file is accessible only when the current processing is completed
by the GX Developer prior to the next processing.
REMARK
For details on the PLOAD instruction, refer to the QCPU (Q Mode)/QnACPU
Programming Manual (Common Instructions).
MELSEC-Q
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