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ETV 0853-3
12.04.2017
Page 31
Note on SRAM Behavior
Because the SRAM (remnant memory) is emulated via the microSD card, there are two
different mechanisms for saving SRAM data to the microSD card:
1. Cyclic writing when data is changed (default)
2. Writing only in the event of PowerFail with a backup time buffered through the
hardware (starting with version 01.02.195)
The advantage of cyclic writing is that in the event of a severe system crash, it's possible to
reference an image of the SRAM data that with the standard settings, is a maximum of 1
minute older than the last change. With extensive use, the amount and frequency of SRAM
data changes from the user program can have a massive effect on the microSD card
lifespan.
Detailed information regarding the SRAM behavior and the corresponding settings can be
found in the LASAL OS documentation, in the chapter “SRAM”.
In the LASAL CLASS project, seldom changed value settings in retentive servers as well
as RamEx and StringRam objects, can be converted to file storage. Should existing objects
be converted from SRAM to File, the loader version 02.02.140 or higher and the RamEx
and StringRam classes of the Tools library version 01.02.033 or higher must be used.
If the user program runs cyclic w
riting processes in files, the tool “Flash Media Lifetime
Calculation” included in LASAL CLASS can be used to determine the effects of the opera-
tions mentioned above on the flash media. This allows the lifespan of the media to be cal-
culated for different, configurable writing scenarios.
