Mares Nemo via IRIS (RS232)

[Jef Driesen]

On 06-01-15 10:30, Stefano Mersi wrote:
>     I have a Mares Nemo and an IRIS RS232 interface. If anyone is
> interested in helping the debug here, I thank them in advance. More
> detailed info follow.
>
>     I have tried to download all the dives from my Mares Nemo via the
> IRIS interface (the old one, which connects through RS232).
>     It apparently did not work using subsurface, so I rolled back to the
> debug tools in libdivecomputer, following the instructions to obtain all
> the needed info. The download with the 'universal' test went smoothly
> from 0% to 100%, but I get periodic warnings: "[6.324485] WARNING: Only
> the first packet has a correct checksum. [in mares_nemo.c:257
> (mares_nemo_device_dump)]" every ~ 100 packets).
>     If anyone is interested in looking into this, I attach all the debug
> info.

With the nemo protocol, each data packet is send twice. You seem to receive many 
data packets with an incorrect checksum, which is a sign of data corruption 
during the transmission (bad/wet contacts?). But as long as at least one of 
those two parts is good, the download can proceed.

Not sure why the download fails in subsurface, but I suspect you had bad luck 
and received a packet where both parts were corrupt. Next time, enable the 
"libdivecomputer logfile" checkbox and send the generated logfile when the 
download fails. Without the logfile I can only guess what went wrong.

Jef