Missing pO2 samples from CCR download [was: 4.7.8: a couple of questions]

Anton Lundin glance at acc.umu.se
Thu May 3 09:52:42 PDT 2018


On 03 May, 2018 - Davide DB wrote:

> On Thu, 3 May 2018 at 13:15, Anton Lundin <glance at acc.umu.se> wrote:
> 
> > On 03 May, 2018 - Davide DB wrote:
> >
> > > On Wed, 2 May 2018 at 11:04, Anton Lundin <glance at acc.umu.se> wrote:
> > >
> > > >
> > > > Try to download them into a fresh logbook with the current desktop
> > > > version, to see what's happens then.
> > > >
> > >
> > > I've just downloaded my dives on a fresh Win10 4.7.8 installation.
> > > As usual after few dives my Petrel quits with "error sending packet
> > error".
> > > I saved some of them anyway and PO2 values are missing.
> > > This is how the petrel controller is recognized. File is attached.
> > >
> > > <divecomputer model='Shearwater Petrel 2' deviceid='1a2d46b1'
> > > diveid='2e7067fb' dctype='CCR'>
> > >
> > > There's no mention of O2 sensor.
> > >
> > > These are all different pertel descriptions of the very same dive
> > computer
> > > I found in my original logbook
> > >
> > > <divecomputer model='Shearwater Petrel 2' deviceid='1a2d46b1'
> > > diveid='3db7eb77' dctype='CCR' no_o2sensors='1'>
> > > <divecomputer model='Shearwater Petrel 2' deviceid='1a2d46b1'
> > > diveid='52d4ba3e' dctype='CCR' no_o2sensors='3'>
> > > <divecomputer model='Shearwater Petrel' deviceid='1a2d46b1'
> > > diveid='a6e05a10' dctype='CCR'>
> > > <divecomputer model='Shearwater Petrel 2' deviceid='1a2d46b1'
> > > diveid='3db24900' dctype='CCR'>
> > >
> > > Were pO2 samples download removed?
> >
> > This is probably because we can't find any calibration values in your
> > computer. Did you get a warning:
> > "Disabled all O2 sensors due to a default calibration value." ?
> >
> > I think the code should fall back to the sensor average po2 when we
> > won't get calibration values for the sensors, but we're not doing that
> > right now.
> >
> 
> Anton,
> 
> I'm not crazy enough to dive a rebreather without a proper calibration.
> Everything is ok on my unit. Cells are new and get calibrated before every
> dive.

Shure. The computer is probably properly calibrated, but the
calibration values found in the memory of the computer are the default
ones. Without those we can't convert the mV values to po2 values.

The cal values might be there somewhere, but we don't know where.

We can't emit the raw mV values, because neither libdivecomputer nor
subsurface supports mV values.
 
> I tried to download again from Shearwater desktop and everything is there:
> pO2 and mV samples. I've never updated my Petrel since we found that
> Subsurface pO2 values were completely wrong so I guess it should be some
> bug arose lately.
> It's sad nobody else (ccr users) replied to my feedback request when I
> noted the pO2 discrepancy. I cannot believe I'm the only one on this list
> using a ccr unit whit a divecan shearwater controller.
>  When I realized pO2 were missing I thought it was something related to the
> mobile download but it's not.
> 
> I would do a full Subsurface download but I drained another battery but I
> do not have a new one around ATM.

We should at least emit the per sample average, when we can't emit the
individual sensor values.

Best would be if we could emit both the "true" average po2 and the
individual sensor values. Unfortunately the interface doesn't support
that distinction.


//Anton


-- 
Anton Lundin	+46702-161604


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