When I have reach the 2 MB limit of my device, there are two options for me: erase the memory and begin fresh, or use "overwrite when full".
For BT747, I know the latter option would force full downloads instead of incremental (smart) ones. But how could I append the new data to my existing log file (.bin)? It seems by the warning message when downloading, that after erasing the memory the log file would be overwritten. What in the case of of overwriting?
Ideally, I could keep one big log. Else, I suppose I have to cycle every month except when a trip spans two months.
Chances are that at the time of erasure of your logger's memory, the logger was in 'Log Overwrite' mode. This information is stored in the header of the log. If that is the case, then BT747 does not know how much information is in the log exactly. The value returned by the logger reflects only the current memory write position. If the memory is being overwritten, this is not indicated by the logger. Therefore, BT747 downloads the entire log to make sure that no data gets lost.