smkt2ssrfgas switching

[Alessandro Volpi]

Dear Salva,

I think it is worth while to spend some words to summarize the sometimes
weird features of the UWATEC hw/sw, related to tanks and gas handling.

Let us start with the naming conventions. The Galileo Trimix sw names the
first tanks (or gases) from T1 to T9.  Tank # 10 is labeled as T0 ; this is
not in principle correct, since any regular sorting procedure would put T0
in the first place, T1 in the second and T9 in the tenth place. Luckily
this potential bug generator is not very effective, since nobody actually
relies in a 10 cylinder dive configuration.

Older sw for Galileo and SmartTec supports only 3 tanks, labeled T1, T2 and
TD. The oxygen volume fraction of T2 ( travel mix) must be equal or higher
than that of T1 (bottom mix) . The oxygen volume fraction of TD
(decompression mix) must be equal or higher the that of T2.

As already said in one of my latest posts the SmarTtec and Galileo programs
do not allow to enter the O2 concentration of T2 if the same parameter has
not been set for TD.

The diver is allowed to switch off tanks T2 or TD before the dive. If TD is
switched off T2 is also automatically switched off. The option of switching
off one or two tanks is useful when said tanks are NOT BEING USED during a
dive. The values of O2 molar fraction and the pairing data for the pressure
transmitter are not erased when a tank is simply switched off.

If a dive is carried out without switching off one or two tanks the sw
assumes that all tanks with a defined O2 fraction and all tanks paired with
the DC are being actually used.

Please note that the tank volume is not defined before the dive. The
Remaining Bottom Time calculation is executed by simple monitoring of the
tank pressure decrease with time.

The tank type and volume definition is manually done  when the data are
downloaded by means of the SmartTrak program. Only when the tank capacity
is defined,  SmartTrak is able to calculate the SAC.

The calculation of the SAC can be executed even when a tank is not equipped
with a pressure transmitter. In this case the Start and End pressure must
be manually entered.

The MOST ANNOYING "feature" of the SmartTrack software is that IT IS NOT
POSSIBLE to MANUALLY enter Start and End pressure when a tank is equipped
with a NON working transmitter ...

The smkt2ssrf program assumes that a tank has not been used during a dive
if the START PRESSURE IS NOT DEFINED. This implies that even the MAIN TANK
description is set to "unknown" when a paired  transmitter is not actually
mounted on the tank or when such transmitter has NOT BEEN WORKING from the
beginning to the end of the dive, so that the Start pressure CANNOT BE
MANUALLY ENTERED.

I agree on the statement that a way MUST BE FOUND for making smtk2ssrf to
ignore the tanks not BEING USED during a dive in spite of fact that their
transmitter has been paired or their O2 fraction of the gas has been
defined:  most divers are too LAZY to switch off non used tanks before the
dive ...

The issue is NOT SO IMPORTANT, but I would suggest that you consider the
possibility of using a different criterion to select the tanks WHICH ARE
ACTUALLY BEEN USED. Such a criterion could be to look for the presence of
the tank DESCRIPTION or the definition of tank VOLUME,  instead of checking
the existence of the START PRESSURE value. It is very unlikely that a
SmartTrak user  is going to waste time with the manual input of data for
tanks which HAVE NOT BEEN ACTUALLY USED. On the other hand the tank type
and/or the tank volume CAN ALWAYS BE MANUALLY INSERTED, even when a
pressure transmitter is paired but not working.

I do not know how much work is required for implementing such program
modification. If this implies a significant effort there are surely more
important things to be done first ...

Very best regards.

Alessandro

On Wed, Mar 8, 2017 at 10:43 PM, Salvador Cuñat <salvador.cunat at gmail.com>
wrote:

> Good night Alessandro.
>
> On Tue, Mar 07, 2017 at 09:51:53PM +0000, Alessandro Volpi wrote:
> >
> > GalileoTrimix tank names range from T1 to T0 ( it should be T10 ... ).
> >
> > Standard UWATEC computer are supporting only 3 tanks, denominated T1 T2
> and
> > TD; TD means Decompression Tank.
> >
> And so did older smarttrak version, jut supported three tanks,
>
> > The problem is that the user is not allowed to define T2 unless TD has
> been
> > defined; for example if you dive with a 15 liter tank with air and a
> small
> > 3 liter tank filled with Nitrox 35, you are forced to call this tank TD
> and
> > not T2.
> >
> Hmmmm, didn't know this "feature", it explains a lot of things.
>
> > Dives #418 and # 419 in my logbook were carried out according to the
> > example.
> >
> I've noticed the duplicity in these dives.
> It's origin is a mix. I'm pretty sure that libdivecomputer reports two
> tanks (say 0 and 1) and just complains about different number of
> tank and mixes (2 tanks, 3 mixes). After parsing the raw data with
> libdc, we have tank_0 and tank_1 (TD for Galileo) with correct initial
> and end pressures and mixes, and a third tank tank_2 with just a mix.
> One of the "features" included in smtk2ssrf is to look into de
> database if we have a tank with a 0 initial pressure, to ensure we
> collect data manually added by the user, so smtk2ssrf reads the TD
> data again and puts it in tank_3 (notice that tank_3 has the type set,
> while tank_2 doesn't in the final .xml file).
>
> > I am sending this message to your attention, since i guess that the gas
> > switch event handling is carried out by smtk2ssrf .. perhaps I am wrong
> >
> Gas switch events are reported by libdivecomputer, directly from the DC
> raw data stored in smrttrak.
>
> I was working on this last sunday, then went quite busy with real
> live. Probably it'll be fixed this weekend, simply removing duplicated
> tanks. This way we can get rid of all (actually, most) unused tanks (up to
> 10)
> and reduce a bit the size of the resulting .xml file.
>
> Regards.
>
> Salva.
>
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