Sorry Tom, I didn't notice how quick your insight was! ;-)
However *(if I may!*), I think that for a better understanding, there would
be (*perhaps?*) another correction to make here:
https://github.com/weewx/weewx/blob/master/ src/weewx/wxxtypes.py#L586
Indeed, you indicate in comments a "rain" field and a "dayRain" field. I
quote *"for calculating observation type 'rain' from a daily total, such as
'dayRain'"* -> OK, thank's for the ifo
But below, dayRain "transforms" into "totalRain":
[StdWXCalculate]
[[Calculations]]
...
rain = prefer_hardware
...
[[Delta]]
[[[rain]]]
input = totalRain
It's certainly not a big problem, but for a neophyte like me, it raises
unnecessary questions when reading the manual... ;-)
Finally, I would like to take this opportunity to ask you if it would not
be possible to provide a new class for a counter that never resets to zero
(DELTA2 for example), which would simply calculate the delta between two
packetsloops (delta2 = measurement2 - measurement1) and if the result is
negative, then delta2 = measurement2 (obviously the counter has been reset).
That would be very cool... ;-)
A (good) idea for development... no ?
Thank you Tom
Le dimanche 28 janvier 2024 à 18:40:37 UTC+1, Tom Keffer a écrit :
> Oh, it was the first thing I did after realizing my omission! Commit
> 9455fa1
> <https://github.com/weewx/weewx/commit/9455fa17169463c3174f3517bdc652c4f2dd5036>
> .
>
> On Sun, Jan 28, 2024 at 7:30 AM Remy Lavabre <remy.l...@gmail.com> wrote:
>
>> thanks Tom,
>>
>> I had thought about putting rain = prefer_software but as this type of
>> rain configuration is not documented in the Weewx documentation (or at
>> least I didn't find it!) I didn't take the initiative. .. stupid I am ! :-(
>>
>> little suggestion Tom, perhaps it would be good to document this point in
>> the [[Delta]] rain class?
>> Well, not everyone is ignorant like me!! :-))
>> Many thanks to you for your help Tom
>>
>> Le dimanche 28 janvier 2024 à 00:21:43 UTC+1, Tom Keffer a écrit :
>>
>>> My apologies. I forgot one important detail. The "[Delta]" section tells
>>> WeeWX how to calculate rain, but you also have to include "rain" under
>>> [StdWXCalculations] / [[Calculations]] in order to get it to do the actual
>>> calculation. It looks like
>>>
>>> [StdWXCalculate]
>>> [[Calculations]]
>>> ...
>>> rain = prefer_hardware
>>>
>>> ...
>>> [[Delta]]
>>> [[[rain]]]
>>> input = dayRain
>>>
>>> On Sat, Jan 27, 2024 at 9:17 AM Remy Lavabre <remy.l...@gmail.com>
>>> wrote:
>>>
>>>> Hello Tom,
>>>>
>>>> I followed your instructions:
>>>>
>>>> 1/“rain” field present in the database
>>>> 2/ “dayRain” field not present in the database
>>>> 3/ My driver returns “dayRain” values and not “rain” values in the
>>>> packetsloop
>>>> 4/ [[Delta]] [[ [rain]]] input = dayRain added in weewx.conf (under
>>>> [StdWXCalculate]).
>>>>
>>>> I did some tests : my driver returns 0.0 for dayRain but unfortunately
>>>> the "rain" field in my database always remains NULL, even after several
>>>> recordings in weewx.conf.
>>>> Shouldn't "rain" field go to 0.0?
>>>>
>>>> THANKS
>>>>
>>>> Le vendredi 26 janvier 2024 à 22:48:03 UTC+1, Tom Keffer a écrit :
>>>>
>>>>> If an observation type never gets reset to zero, you have two choices.
>>>>> 1. Save the value. If you want to know daily use, take the difference
>>>>> of the value.
>>>>> 2. Save the difference. That is, the change in the value over an
>>>>> archive period. If you want to know daily use, you would sum all the
>>>>> small
>>>>> deltas. This is like rain
>>>>>
>>>>> See the discussion *Accumulated vs delta energy
>>>>> <https://github.com/tkeffer/weewx-brultech?tab=readme-ov-file#accumulated-vs-delta-energy>*
>>>>> in
>>>>> the README of the Brultech driver for the pros and cons of the two
>>>>> approaches.
>>>>>
>>>>> It is not necessary to save "dayRain". WeeWX mostly uses "rain".
>>>>> Besides, as you note, it can always be calculated.
>>>>>
>>>>>
>>>>>
>>>>> On Fri, Jan 26, 2024 at 7:06 AM Remy Lavabre <remy.l...@gmail.com>
>>>>> wrote:
>>>>>
>>>>>> And one more question....
>>>>>> Is it absolutely necessary to create a "dayRain" field in addition to
>>>>>> the "rain" field in the weewx.sdb database?
>>>>>> If the database only contains the [rain] field but the Weewx driver
>>>>>> returns a "dayRain" field (cumulative rain over 24 hours since midnight)
>>>>>> with a real value in each packetloop, the class [[Delta]] [[ [rain]]]
>>>>>> input
>>>>>> = dayRain will it work??
>>>>>> (the accumulation of rain since midnight is useless to me in a
>>>>>> database field since it is easily calculated)
>>>>>> Sorry for all the questions...and thanks again! ;-)
>>>>>>
>>>>>> Le vendredi 26 janvier 2024 à 15:46:04 UTC+1, Remy Lavabre a écrit :
>>>>>>
>>>>>>> Hello Tom and thank you for your response.
>>>>>>>
>>>>>>> [StdWXCalculate]
>>>>>>> [[Calculations]]
>>>>>>> ...
>>>>>>> [[Delta]]
>>>>>>> [[[rain]]]
>>>>>>> input = dayRain
>>>>>>>
>>>>>>> This will calculate the rain difference between two records in weewx
>>>>>>> sql based on the principle that the counter is reset to zero at
>>>>>>> midnight ->
>>>>>>> PERFECT FOR THE RAIN 24H !
>>>>>>>
>>>>>>> Small additional question: if we wish to constantly calculate the
>>>>>>> difference between two records values of a meter which *never*
>>>>>>> resets to zero (such as an electricity or water meter), how should we
>>>>>>> proceed?
>>>>>>>
>>>>>>> THANKS
>>>>>>>
>>>>>>> Le jeudi 18 janvier 2024 à 14:05:10 UTC+1, Tom Keffer a écrit :
>>>>>>>
>>>>>>>> Unfortunately (for you), WeeWX mostly uses observation type "rain",
>>>>>>>> the amount of rain that fell since the last loop packet (what you are
>>>>>>>> calling "instantaneous rain").
>>>>>>>>
>>>>>>>> You should assign the rain since midnight to type "dayRain".
>>>>>>>>
>>>>>>>> Then calculate "rain" as the difference between successive
>>>>>>>> "dayRain" values. While this is a pretty simple calculation, there is
>>>>>>>> an
>>>>>>>> xtype that can do it for you. See class Delta in weewx.wxxtypes
>>>>>>>> <https://github.com/weewx/weewx/blob/master/src/weewx/wxxtypes.py#L586>.
>>>>>>>>
>>>>>>>> To use it, add this to weewx.conf:
>>>>>>>>
>>>>>>>> [StdWXCalculate]
>>>>>>>> [[Calculations]]
>>>>>>>> ...
>>>>>>>> [[Delta]]
>>>>>>>> [[[rain]]]
>>>>>>>> input = dayRain
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Wed, Jan 17, 2024 at 11:47 PM Remy Lavabre <remy.l...@gmail.com>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> Good morning,
>>>>>>>>>
>>>>>>>>> I created a [driver] for weewx to retrieve data from the Awekas
>>>>>>>>> API (my Bresser weather station does not have a USB port).
>>>>>>>>>
>>>>>>>>> This works but regarding the rain, it is not the instantaneous
>>>>>>>>> rain (from a packetloop) that we recover but the rain over 24 hours
>>>>>>>>> since
>>>>>>>>> midnight.
>>>>>>>>> Is there a "simple" way to tell WeeWX that the packetsloop rain
>>>>>>>>> data corresponds to the cumulative rain since midnight and not the
>>>>>>>>> rain
>>>>>>>>> that fell during the data retrieval interval (the time gap between
>>>>>>>>> two
>>>>>>>>> packetsloops) ?
>>>>>>>>>
>>>>>>>>> Thank you so much...
>>>>>>>>>
>>>>>>>>> --
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>>>>>>>>>
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>>>>>>>>>
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>>>>>>
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