To understand what could be going wrong you need to understand how WeeWX 
obtains the three pressure values. For Davis stations the vantage driver 
emits WeeWX field barometer and WeeWX then calculates pressure and altitude. 
pressure is calculated first using values for barometer, outTemp and 
outHumidity as well as outTemp 12 hours ago. If any of these values do not 
exist pressure is not calculated. WeeWX then calculates altimeter using the 
just calculated pressure value and station altitude. If either of theses 
values do not exist then altitude is not calculated.

Given that you have no missing barometer data it is quite possible the lack 
of pressure and altimeter is due to missing outTemp or outHumidity. If both 
outTemp and outHumidity are present it could be missing outTemp from 12 
hours ago. Try adding outTemp and outHumidity to your query, if both fields 
are present look at outTemp 12 hours (or 43200 seconds) ago.

Hopefully this should reveal the final part of the reason why pressure and 
altimeter are not being calculated, but it won't show the underlying cause. 
I cannot think of a reason why any of the obs concerned 'disappear' at/near 
sun rise/set. Is this repeatable, ie happens every day or is it sporadic? 
If every day then try stopping the WeeWX daemon and run WeeWX directly 
before sunset and observe the loop packets (LOOP: lines) and archive 
records (REC: lines) on the console and see what obs disappear when. 

You do have a very short archive interval of one minute, though your 
station should be emitting loop packets every two odd seconds so WeeWX 
should be seeing multiple loop packets each archive period. On top of that 
each loop packet should contain outTemp, outHumidity and barometer (unlike 
some stations that do not include all obs in each loop packet). So whilst 
short, I don't think your archive interval is contributing to the problem.

Gary
On Friday, 28 April 2023 at 05:28:45 UTC+10 [email protected] wrote:

> Hi, 
> two times a day, the pressure from mu davis vantage vue is beeing 
> calculated as null
>
> here is the mysql archive:
> MariaDB [weewx]> select 
> from_unixtime(datetime),barometer,pressure,altimeter from archive order by 
> datetime desc limit 50;
>
> +-------------------------+--------------------+--------------------+--------------------+
> | from_unixtime(datetime) | barometer          | pressure           | 
> altimeter          |
>
> +-------------------------+--------------------+--------------------+--------------------+
> | 2023-04-27 18:36:00     |             30.035 |               NULL |     
>           NULL |
> | 2023-04-27 18:35:00     |             30.035 |               NULL |     
>           NULL |
> | 2023-04-27 18:34:00     |             30.034 |               NULL |     
>           NULL |
> | 2023-04-27 18:33:00     |             30.034 |  26.58821997477311 | 
> 30.160739007773113 |
> | 2023-04-27 18:32:00     |             30.034 | 26.588551871590237 | 
> 30.161106590655088 |
>
> it happens every day near down and dusk
>
> i couldnt find anything in the logs
> wee_device --current is reading the barometer OK
>

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