How long can I record data with the "HDLog to File FBox" (in csv format) using a 1 GB SD Card?

FAQ #101437

 

Memory available on a 1 GByte SD card
1 GB SD Card (PCD3.R600 with PCD7.R-SD1024) has 1’073’741’824 bytes
Note: It is not recommended to fill the SD card completely; in general we recommend only using 50% of the available memory in case data is written (and deleted) regularly.
Further on the maxumum amount of files per SBC file system is 900 in total, and every directory counts as 20 files (because the folder "WEBPAGES" and "CONFIG" always exists, the maximum amount of files which can be created on a SD card is around 850 (860 to be precise).

Memory requirement of log files
The memory requirement of files created by the "HDLog to File" FBox (log in csv format) is calculated as follows:
Possible records = 50% of memory capacity (in bytes) / required characters per record (in bytes)

Examples

• Writing 30 values to an SD card
  In case 30 values are to be recorded:
  Each value has an average number of six characters (exp. 123,4).
  Each HD Log File FBox requires 30 characters for the date and timestamp.
  So 30 record sets, subdivided into 3 FBoxes requires about 270 bytes per record (rounded about 300 bytes per record, including date and time stamps).
  1 GB SD Card (PCD3.R600 with PCD7.R-SD1024) = 1’073’741’824 bytes
  This results in about 3,500,000 entries. Due to the fact that you should not fill the SD card over 50% there remain effective 1'700'000 entries.
  At a recording interval of 5 minutes the SD card has space for about 16 years, given one file per month is generated (--> 16 years * 12 files/year * 3 FBoxes = 576 files)
  
  

  Remark regarding this example
  In case one file is generated per week, after around 5.5 years it won't be possible creating more files because of the maxumum number of files per file system has been reached (5.5 years * 52 files/year * 3 FBoxes = 858).

  
  
• Writing 3 values to a PCD7.R550 memory card
  In case 3 values are to be recorded:
  Each value has an average number of six characters (exp. 123,4).
  Each HD Log File FBox requires 30 characters for the date and timestamp.
  So 3 record sets can be recorded with one FBox and requires 48 bytes per record (rounded about 50 bytes per record, including date and time stamps).
  1 PCD7.R550 module = 4'000'000 bytes
  This results in about 80'000 entries. Due to the fact that you should not fill the SD card over 50% there remain effective 40'000 entries.
  At a recording interval of 1 minute the memory module has space for about 1 month (28 days)