new install (4.8) using the GW1000 extension - missing ET?

[John Hill]

Sorry - this is going to sound poorly informed... but here it goes.

I've been running weewx for years since the 3.x days.  Using the interceptor driver - first with the Ambient Weather devices, now with Ecowitt using a GW1000 as a gateway.

During that time I made numerous tweaks to the file system, changing skins, schemas, adding extensions, removing extensions, running through hubitat, then nodered, etc.  Of course, I'm not very good at documentation, so each change I made would eventually get pushed out of my brain in favor of the new project du jour.

I noticed a new gw1000 extension and thought maybe now would be a good time to wipe the slate and see what works out of the box.

Surprisingly, most everything does.  I do see some label and unit changes for radiation (used to be wmp2/radiation, now it's lux/luminosity).

But the most noticeable changes is I'm now missing ET.  Not sure how.  I don't remember having to do anything in my prior install to get it to calculate.

confirmed in sqlite that it's not in the archive:

sqlite> select dateTime,ET,radiation,UV from archive order by dateTime desc limit 4;

1656952200|||6.0

1656952140|||4.0

1656952080|||2.0

1656952020|||3.0

It's in my wview.py schema and in my skins.conf:

        [[[dayET]]]

            # Make sure the y-axis increment is at least 0.02 for the ET plot

            yscale = None, None, 0.02

            plot_type = bar

            [[[[ET]]]]

                aggregate_type = sum

                aggregate_interval = hour

                label = Evapotranspiration (hourly total)

have tried both prefer-hardware and software in my weewx.conf for ET calcualtion.

Hope it's obvious, but what am I missing?

[Tom Keffer]

In order to calculate ET, you'll need outside temperature, radiation, and humidity. From your query, you don't have radiation, and possibly the others. Make sure they are all there.

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[gjr80]

Ecowitt Gateway devices provide a measure of luminosity in lux rather than a measure of solar insolation in watts/square metre (as used by WeeWX in the radiation field). There is a simple linear approximation for radiation given a luminosity value in lux by dividing the luminosity value by 126.7. This is what Ecowitt Gateway devices use when posting to Ecowitt.net or WeatherUnderground etc. Within WeeWX it is not appropriate for the Ecowitt gateway driver to implement this approximation , rather it should be applied by adding a correction entry to the [StdCalibration] [[Corrections]] stanza in weewx.conf. More detail (including implementation of the radiation field approximation) is covered in the Ecowitt gateway device wiki page Understanding GW1000 radiation fields.

Once you have the radiation field being calculated you should should find that ET is also calculated provided you have the other pre-requisites outlined in Tom's post are available. 

Gary

[John Hill]

omg... it was right there in the wiki.  So sorry to bother you.  Plugged in the formula and it's working great.  Thanks!