The SD Card logging limits are 20 000 lines multiplied by 50 files. The maximum record count is 1million seconds - only 11 days.
But in one line could be written several parameters (in fact 32 as tested). So if the first parameter is second 1, the next second 2 and up to second 32. Collect 32 second's  data and then write the one log line. You even got the 3 days in reserve.
This solution may be is not wery practical (only one parameter saved) but ilustrates very vell the limits of SD Card logging.

The same technique could be used to overcame the 500ms recording delay - so a litle faster data could be saved.

Aivars

The SD Card logging limits are 20 000 lines multiplied by 50 files. The maximum record count is 1million seconds - only 11 days.
But in one line could be written several parameters (in fact 32 as tested). So if the first parameter is second 1, the next second 2 and up to second 32. Collect 32 second's  data and then write the one log line. You even got the 3 days in reserve.
This solution may be is not wery practical (only one parameter saved) but ilustrates very vell the limits of SD Card logging.

The same technique could be used to overcame the 500ms recording delay - so a litle faster data could be saved.

 Is this a recommendation for LOGO?!  Please write more details.

BR,

Noodles

Not exactly recomendations (more - how to go beyond limits).

Siemens information:

"Data Log" from LOGO! System Manual states:

-20 000 lines per file

-50 files maximum

-500ms between log (that's Siemens recomendation) may be faster SD Cards have smaller write time?

-32 parameters per line (just tested by myself)

For reference "Data Log" chapter -2 pages, user forum about r/w to SD card 200 -entries!

ixo65

I still don't understand what you're trying to tell us.

From section Tips and Tricks. It's possible that you do everything according to the manual and because of that you don't understand. Same story as retaining an analog value - according to manual, it can only be done with a counter and it is not the most convenient way either.

WWEE

 

ixo65

I still don't understand what you're trying to tell us.

From section Tips and Tricks. It's possible that you do everything according to the manual and because of that you don't understand. Same story as retaining an analog value - according to manual, it can only be done with a counter and it is not the most convenient way either.

The original poster showed a idea how with some kind of buffering (shift register?) you can write data for a longer period of time to the SD card without sacrifiying granularity.

Imagine that it is necessary to record the data of only one analog input for two months at one second intervals (some kind of datalogger). In the standard way, you can save only last 11 days of data this way (Datalog function is some kind of ring buffer).

 Exactly. The project aim is accumulator charge/discharge current and may be voltage monitoring for a long period. The SD Card could be replaced, but not too frequently. The maximum record count and intervals are calculated. I read manuals and lot of user entries. In may application the 500ms period is ok (analog input rate for LOGO itself is 300ms). With the same idea I could record digital inputs with 10ms intervals (storing them at 500ms). Interesting the 500ms limit - is it LOGO delay or SD Card timing (cards also could differ).