...and it looks like the weewx-mqtt extension already has the ability to do
just that - specify unit overrides. Taking a look at the weewx-mqtt code
has this comment:
[StdRestful]
[[MQTT]]
...
unit_system = METRIC # default to metric
[[[inputs]]]
[[[[outTemp]]]]
name = inside_temperature # use a label other than outTemp
format = %.2f # two decimal places of precision
units = degree_F # convert outTemp to F, others
in C
[[[[windSpeed]]]]
units = knot # convert the wind speed to knots
So, Colin, you could try altering the mqtt settings in your weewx.conf to
this example below. This example worked for me. I had 0.3 inches of rain
today, after adding the below and a weewx restart it changed it from
dayRain_in to dayRain_mm and was showing 7.62 which converts correctly.
Everything else stayed as it was.
[StdRestful]
[[MQTT]]
...
unit_system = METRIC # default to metric
[[[inputs]]]
[[[[dayRain]]]]
name = dayRain_mm
units = mm
And based on your comment on GitHub
<https://github.com/poblabs/weewx-belchertown/issues/23#issuecomment-440458755>,
I think this is what you want.
METRIC wind (km/h) - default by the unit_system = metric
METRICWX rain (mm) - overridden by the input above
On Tuesday, November 20, 2018 at 10:05:27 PM UTC-5, Pat wrote:
>
> Thinking about this further, I said:
>
> So would the answer be to have weewx-mqtt transmit in METRICWX and then
>> specify in the skin options group_wind = km_per_hour? Or would that
>> cause some miscalculations of wind data?
>
>
> This would be invalid because the base skin would probably do the
> conversion, but the MQTT published message would have wind in m/s since the
> weewx-mqtt is setup for METRICWX (in this example). So no matter what I
> would display that observation as the published m/s but with a label of
> km/h on the page.
>
> I think I keep going back to the idea of having the weewx-mqtt
> <https://github.com/weewx/weewx/wiki/mqtt> send specific observations in
> the unit the user wants. Similar to a skin's [[[Units]]] [[[[Groups]]]]
> setup.
>
>
> On Tuesday, November 20, 2018 at 9:57:20 PM UTC-5, Pat wrote:
>>
>> The Belchertown skin extension allows users to specify which group units
>> they want (much like the standard skin). I think this Issue on my GitHub
>> repo
>> <https://github.com/poblabs/weewx-belchertown/issues/23#issuecomment-440477408>
>> (which
>> Colin started) tries to a) get my own head wrapped around this and b)
>> suggest that the weewx-mqtt extension have the ability to also send
>> specific observations in the unit they want. Similar to a skin setup.
>>
>> The MQTT extension can specify which units to transmit values in - but
>> it's an all or nothing conversion (US, METRIC, METRICWX). However based on
>> the table in the GitHub link (also attached here), I think what's trying to
>> be determined is if a hybrid scenario can exist somehow? Is that up to the
>> skin or up to the MQTT extension's transmit values?
>>
>> So would the answer be to have weewx-mqtt transmit in METRICWX and then
>> specify in the skin options group_wind = km_per_hour? Or would that
>> cause some miscalculations of wind data?
>>
>> An additional layer on top of all of this is that my skin just displays
>> what's present in MQTT. So if MQTT is sending dayRain_cm, I display that
>> even if the user wants dayRain_mm. So I think it would make sense for the
>> mqtt extension to be able to have granular ability on altering certain
>> observations. Otherwise the live-updated data coming from MQTT would have
>> to do in-situ conversions within the JavaScript functions (outside of weewx
>> conversion utilities) - which is another layer of complexity I'd like to
>> avoid if possible.
>>
>> Lastly, if I'm not mistaken I think Colin's database is in US units based
>> on previous conversations we've had.
>>
>> On Tuesday, November 20, 2018 at 8:23:05 PM UTC-5, gjr80 wrote:
>>>
>>> Colin,
>>>
>>> US, METRIC or METRICWX merely defines the units used in the weeWX
>>> database, it really should have no bearing on the presentation of data. For
>>> example, in the weeWX Standard skin (and for that matter other skins that
>>> simply use the weeWX report system for generating reports) the weeWX tag
>>> system and config settings in skin.conf/weewx.conf determine what
>>> presentation units are used. The user can freely (and simply) change these
>>> settings to display whatever units he/she requires in the resulting
>>> reports. Of course once you step outside extensions that only use the weeWX
>>> reporting system things become a little more complex, chnaces are you
>>> cannot rely solely on the weeWX tag system. In my view it really behoves
>>> those that produce extensions to weeWX to provide a means of selecting the
>>> units displayed by their extension, this may be as simple as the tags and
>>> skin/weewx config as previously mentioned, or for more complex extensions
>>> that say use MQTT or some other external app/system then some other
>>> mechanism is required. I am not fully across Pat's Belchertown extension
>>> but given it is still relatively young and being actively developed I would
>>> hope Pat would include some sort of user selectable settings/config options
>>> that allow you to display in whatever units you wish irrespective of the
>>> underlying database units.
>>>
>>> In getting back to your original question I suspect there is not too
>>> much that can be done by you to change things unless the Belchertown
>>> extension has some as yet unknown config settings to do what you want. Pat
>>> or other Belchertown users are the best placed to help with this. I also
>>> suspect there is little you can do directly to weeWX. If it was me I would
>>> be using US customary units in my database unless you have good reason not
>>> to (* see note) and I would be approaching Pat for a means to allow the
>>> user to alter the Belcherton presentation units.
>>>
>>> Note: FWIW I am in Australia and prefer to be able to view metric data
>>> on the odd occasion I want to look at my raw database data so I run METRIC
>>> (when I first started using weeWX there was only US or METRIC, METRICWX
>>> came later), I just have to keep reminding myself that rain is in cm. I
>>> also do all my development work using a US units database and since I
>>> mostly develop for my requirements that way I am forced to make sure I have
>>> a mechanism to display metric units.
>>>
>>> Gary
>>>
>>> On Wednesday, 21 November 2018 10:06:16 UTC+10, Colin Larsen wrote:
>>>>
>>>> Hi all
>>>>
>>>> I'm putting this out on the Weewx forum as I'm not sure if there is a
>>>> simple answer within Weewx for this problem.
>>>>
>>>> Down in NZ it is common to report rain in mm and wind speed in kp/hr
>>>>
>>>> In publishing MQTT data for Pats Belchertown skin this is causing an
>>>> issue whereby if I set MQTT to publish Metric I get wind speed and gust in
>>>> kp/h ..... but rain is reported in CM. Pats skin looks at the group units
>>>> which I have set to mm for rain and publishes the data, which is CM as he
>>>> sees the MQTT data is Metric and I get 0.14 mm of rain instead of the
>>>> 1.4mm
>>>> it should be. Same for rain rate of course.
>>>>
>>>> I can fix the rain by using Metricwx which publishes rain in mm - but
>>>> then wind is in m/s so that reports wrong as the group units are kph.
>>>>
>>>> Can anyone suggest a solution within Weewx to the conundrum?
>>>>
>>>> Many thanks
>>>> Colin
>>>>
>>>
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