Write in a CSV file located in a SDCARD each second

[MAIDEL]

Hello,

I have an application working on a TP700 Comfort panel (developped with WinCC Advanced on TIA Portal V11). In this application I am writing values from 5 variables each x second (have to be variable) in a CSV file in a SD Card, and I asked myself "if I write a lot in the SD Card like this, I may have a problem because the SD Card has a maximum write cycle number". I thought about the log modul of WInCC adavanced but I don't understand why we don't have this problem with this modul (if what I think about the maximum write cycle number is true problem with my application)

Second thing, if the WinCC modul is really the soultion, I will have two problem:
- make the logging cycle variable (in the WinCC modul you have to specify 1 second or 2 second, ... and it will not be variable)
- before writing my values I am writing a header (date, customer name, project name, ...) and the modul doesn't allow me to insert any data before the log

Thanks for helping me and sorry for my poor english (you guessed ... I'm French

)

 

[JesperMP]

It could be an issue with writing to a flash drive every second 24/7.
Here is a PDF describing that it should be possible to write to flash drives for millions of times if 'wear levelling' is used.
http://cfgearblog.blogspot.dk/2011/03/how-long-does-flash-drive-last_22.html
But millions of writes will only be enough for a few months.
I believe that industrial grade flash cards use wear levelling, but comercial grade maybe not.

Anyway, I find it inconvenient to use a flash card for logging data.
How to get the data out of the card ? You have to remove the card at frequent intervals, and you will have to wait for that for the data to be available.
I think a much better solution would be to log to a network drive, and that will also remove the potential problem with the number of write cycles on the flash card.

 

[MAIDEL]

Hi,

Thank you for your answer.
I am using this kind of Card "SD Card is 6AV6671-1CB00-0AX2SIMATIC (HMI MMC 128 MO)"

Unfortunally, I have to use a SD Card because our machine will be outside (in a oil and gas site) and has to be a standalone machine. But I would like t ounderstand something:
why the Log module in WInCC is reliable for this task, is the log module does not write the value in the CSV file each second? or maybe the log module write the value in the RAM and then write on the SD Card to avoid to write each second? if you have any document which explain this I will be very happy to read and have it for the future.

Thank you.