I have taken my SD card, locked it and then placed it in my reader.
I have the downloaded all readings for the past 675 days into Sleepyhead and Encore Basic.
Both Sleepyhead and EncoreBasic function and report as I would expect!
Meanwhile, whilst doing this, I have placed another unlocked freshly formatted SD card into my CPAP machine.
The CPAP machine gave the notice of activity.
I have then safely ejected the first SD card, unlocked it and placed it in the CPAP machine.
I have taken the second SD card, locked it and then placed it in my reader.
I have the downloaded all readings into Encore Basic.
Now here is the interesting observation.
ONLY 154 DAYS DATA is reported, not the 675 days expected! I have tried this three times with the same result!
EncoreBasic functions and reports as I would expect, prompting a question. Does my machine have the capacity to only store 154 days of data, and merely adds each new day to the end of the "queue".
Has anybody else observed this?