Archive records are what are stored in the database. A Vantage station
produces its own archive record (unless record_generation is set to
'software'). However, for whatever reason, Vantage stations do not include
dewpoint in the hardware generated record, so WeeWX must calculate it. By
default, WeeWX calculates the average dewpoint seen over the archive
interval. If dewpoint changes over the interval, the average is not
necessarily an even number.
One way around this is to have WeeWX calculate the last value seen, instead
of the average. Add this to the end of your weewx.conf file:
[Accumulator]
[[dewpoint]]
extractor = last
Alternatively, what sort of external programs are you writing? Does the
language you are using provide a way to format decimal output?
-tk
On Sun, Aug 16, 2020 at 3:16 PM satwa...@gmail.com <satwatch...@gmail.com>
wrote:
> Hi,
>
> I searched the group for this subject and couldn't find anything so I am
> posting.
>
> I have the Vantage Pro 2, serial interface to Weewx 3.9.2 run on an Ubuntu
> server.
>
> Below is a sample line from the archive database (broke into individual
> lines due to width) using the command:
> sqlite3 -header -csv /var/lib/weewx/weewx.sdb "select * from archive;"
>
> One line from the output:
> 1597612740,1,1,29.617,28.0238601652778,29.7814033867068,83.7,*115.4*,
> 38.0,18.0,0.0,,1.0,225.0,0.0,0.0,*61.1737982063856*,115.4,
> 115.4,0.0,,,,,,,,,,,,,,,,,,,,93.9583333333333,0.0,5.31,,,,,,,,,,
>
> Note the temperature is reported as 115.4 degs (ugh...this is Arizona).
> The dewpoint is reported as 61.1737982063856. All dewpoint values in the
> database have a decimal precision of 13 places, clearly outside the sensor
> quality range. The sensor documentation indicates that it provides Relative
> Humidity values so apparently the console software derives the dewpoint
> value as it can be displayed on the console. I write a lot of external
> programs and have to repeatedly reduce the precision for this variable.
>
> Is there an easy way to modify my Weewx to store only 1 decimal place for
> dewpoint or other variables? I did check /etc/weewx/weewx.conf and could
> not find any obvious setting for this.
>
> Thanks for any assistance,
>
> Ken
>
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