SD Card regularly having corrupted files

[MAL]

I have multiple v700s that are storing trend data.  Over time (months to a year) the files are corrupting.  I have seen them corrupt in multiple locations on the SD but generally in the trend data.  I have a max of 250 trends that are stored.  When it reaches 250 files it resets to 1.  Is there a limit to the number of files the PLC can manage or is it most likely the re-writes?  I am not sure what the actual limits of the PLC are.  From experience there are odd little facts that are not covered in the manuals.

[Ausman]

Hi Mal,

Trends and other File types do have limits, and these are listed in Help under SD Cards.  Scroll down a bit to Folders and File Types.

Trends are listed as a total of 320 .utr spread across subfolders. Generally the rule seems to be for the number in a folder to be 64.

Please note other topics in the forum where corruption has occured and limits seem to be able to be exceeded.  For what it's worth, I've been trying a quality Toshiba SD in a system that routinely corrupted things, and for a year or so now it has been fine, so I an inclined to believe that "although all cards are created equal, some are better than others!"  But it does appear that the PLC only really likes working with 64 in a folder.  However, some of my experiences are more than that in sub-folders, but they don't show properly if more than 64.

cheers, Aus

[Flex727]

20 minutes ago, Ausman said:

For what it's worth, I've been trying a quality Toshiba SD in a system that routinely corrupted things, and for a year or so now it has been fine, so I an inclined to believe that "although all cards are created equal, some are better than others!"

SD card quality is a big problem today. Many of the Chinese knock-offs are horrible and will corrupt quickly and easily. I stick with name brands now, no matter the cost.

[Fernando Castro]

I had one or two corrupted SD cards per month among my 180 PLCs.

SanDisk 16 Gb from Amazon, and I don't even wrote to often, It was used more like a read only memory for managing recipes.

Also the 64 file limit is kind of mysterious, you can store more than 64 but won't be written  into the SD card, if you have 64, then record another 10 files, the most 10 recent files will appear on the SD card only if you delete other 10 or more files in the SD Card, where are those other files stores, who nows 🤷‍♂️, what is the actual limit in that phantom storage its also a mystery.

[kratmel]

From help...

Having analyzed the research outlined in this post

https://stackoverflow.com/questions/2651907/is-there-a-limit-for-the-number-of-files-in-a-directory-on-an-sd-card

I concluded that the limitation in the number of files in the folder occurs due to the maximum length of the file name reserved in the PLC. That is, since the PLC is not a PC, it is probably impossible to implement a full mode of interaction with the SD card. Therefore, in advance, the developers limited the number of files so as not to exceed the capabilities of the file system when writing the appropriate file names.

[Flex727]

11 hours ago, kratmel said:

I concluded that the limitation in the number of files in the folder occurs due to the maximum length of the file name reserved in the PLC. That is, since the PLC is not a PC, it is probably impossible to implement a full mode of interaction with the SD card. Therefore, in advance, the developers limited the number of files so as not to exceed the capabilities of the file system when writing the appropriate file names.

This really makes a ton of sense. Thanks for the great research and analysis.

[MAL]

Thank you all!  I was considering the 320 files total in any folder.  Not per directory.  I will try this out.  We haven't had any issues with the read or writes. just eventual corruption.  if it can't handle that many then it would make sense that corruption can occur.