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CHAPTER 9 SD MEMORY CARD
For the specifications and part names of SD memory cards, refer to the following.
MELSEC-L CPU Module User's Manual (Hardware Design, Maintenance and Inspection)
9.1 Precautions for Using SD Memory Cards
This section describes the precautions for using SD memory cards.
(1) Power-off or reset of the CPU module while accessing the SD memory card
If the CPU module is powered off or reset while the data in the buffer is being stored to the SD memory card, the
file system of the SD memory card may corrupt. In this case, the CPU module diagnoses the SD memory card
(checks the file system and restores data) upon power-on or reset.
Note, however, that the file system may not be completely restored depending on the corruption.
The following processing time is required to diagnose the SD memory card (if 10000 files are stored in it).
*1*2
• L1MEM-2GBSD: approximately 5 seconds
• L1MEM-4GBSD: approximately 13 seconds
*1 The time for diagnosis is longer as the number of files in the SD memory card increases.
*2 When an external communication device is connected to the CPU module, if they are simultaneously activated, a
communication timeout may occur on the external communication device side.
(2) Time for saving data to an SD memory card before data logging stop or pause
Data logging is stopped or temporarily stopped after all the collected data are saved in the SD memory card. For
this reason, it takes time for the actual data logging operation to stop or pause after a stop or pause operation is
performed. (When a small value is set for "Number of records" or "File size" in "File switch timing", it takes longer
time.)
For operations associated with the above data saving to an SD memory card, refer to Page 72, Section 6.8
(11).
The operating status of the CPU module does not change during data saving to an SD memory card.
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