Uwatec Smart Z data download takes 1.5 hours for only 4 dives

Dirk Hohndel dirk at hohndel.org
Mon Dec 23 13:25:11 UTC 2013

On Mon, 2013-12-23 at 22:21 +0100, Jef Driesen wrote:
> Unfortunately that's a limitation of how subsurface implements the "download 
> only new dives" feature. Subsurface starts downloading dives, and aborts the 
> download once a previously downloaded dive is recognized. But the Uwatec 
> protocol forces you to always download ALL dives at once, unless you tell it not 
> to do that. This works by sending a device timestamp to the device during 
> handshaking, and then the device will only return those dives that are more 
> recent than the timestamp (e.g. only the new dives). This is available in 
> libdivecomputer through the fingerprint feature, but subsurface doesn't use it.
> @Dirk: This is one of those cases where a custom "download only new dives" 
> implementation will always be less efficient than libdivecomputer's built-in 
> fingerprint based implementation.

Linus - I don't remember why we did not use the fingerprint based
implementation... can you remind me?

> > Another small issue I encountered: the dive download dialogue window does not
> > remember the irda0 port setting, but returns to /dev/ttyS31.
> Doesn't matter, because the device node isn't used. IrDA communication uses 
> sockets, which don't need a device node at all.

We really need to add code that recognizes the dive computers that don't
need a device node and then simply gray that field out.

Anyone interested in working on that? It shouldn't be all that hard -
work with Jef to figure out which DCs don't need a device node,
recognize them in the downloading Widget and if the user selects one of
them disable the input field...


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