Calculating delta from running total

[bell...@gmail.com]

I am pretty sure that WeeWX can calculate the delta of an observation from a running total (for example a driver/service that reports a cumulative value for rain). I have searched the WeeWX docs and wiki, but I can't find out how to do it. Could someone point me to the documentation or wiki page?

Thanks! rich

[John Smith]

Over what time period?

On Tue, 25 Nov 2025 at 12:01, bell...@gmail.com <bell...@gmail.com> wrote:

I am pretty sure that WeeWX can calculate the delta of an observation from a running total (for example a driver/service that reports a cumulative value for rain). I have searched the WeeWX docs and wiki, but I can't find out how to do it. Could someone point me to the documentation or wiki page?

Thanks! rich

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[Tom Keffer]

There is an XType service Delta that can do this. For example, it is used to calculate rain from a running total:

    [StdWXCalculate]
        [[Calculations]]
            ...
            rain = prefer_hardware
            ...
        [[Delta]]
            [[[rain]]]
                input = totalRain

On Mon, Nov 24, 2025 at 5:01 PM bell...@gmail.com <bell...@gmail.com> wrote:

I am pretty sure that WeeWX can calculate the delta of an observation from a running total (for example a driver/service that reports a cumulative value for rain). I have searched the WeeWX docs and wiki, but I can't find out how to do it. Could someone point me to the documentation or wiki page?

Thanks! rich

--

[bell...@gmail.com]

Bingo! Thanks Tom!

Nitpicking a bit, should this be added to, https://weewx.com/docs/5.2/reference/weewx-options/stdwxcalculate/

rich