Re: [weewx-development] Database data in driver

[Tom Keffer]

This is explained in the guidelines for writing a new driver in the Customizing Guide. In particular, the paragraph:

A couple of observation types are tricky. In particular, rain. Generally, WeeWX expects to see a packet with the amount of rain that fell in that packet period included as observation rain. It then sums up all the values to get the total rainfall and emits that in the archive record. If your hardware does not provide this value, you might have to infer it from changes in whatever value it provides, for example changes in the daily or monthly rainfall. 

This means you save the first value for daily rain you see, and compare it to the next value. The field 'rain' is the difference.

-tk

On Fri, Jun 26, 2020 at 4:17 PM Bastiaan Meelberg <bast...@meelberg.com> wrote:

Hi,

I'm working on a Weatherlink Live driver, WLL is giving a daily rain. The driver looks for a difference and adds the difference to the loop and sets the old value. 

Starting weewxd this counter is set to zero. But if there was rainfall all this rain is added again to the loop.

So e.g. if there was 2 mm of rain fell during the day, and after a restart, the driver adds this 2 mm to the loop (again), and is seen as new rain.

Is there a way to get this daily rain data from the database and set it in python as the starting variable?

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[Bastiaan Meelberg]

Thanks for you answer! Sometimes the solutions is so simple.

On Saturday, June 27, 2020 at 3:56:42 AM UTC+2, Tom Keffer wrote:

This is explained in the guidelines for writing a new driver in the Customizing Guide. In particular, the paragraph:

A couple of observation types are tricky. In particular, rain. Generally, WeeWX expects to see a packet with the amount of rain that fell in that packet period included as observation rain. It then sums up all the values to get the total rainfall and emits that in the archive record. If your hardware does not provide this value, you might have to infer it from changes in whatever value it provides, for example changes in the daily or monthly rainfall. 

This means you save the first value for daily rain you see, and compare it to the next value. The field 'rain' is the difference.

-tk

On Fri, Jun 26, 2020 at 4:17 PM Bastiaan Meelberg <bast...@meelberg.com> wrote:

Hi,

I'm working on a Weatherlink Live driver, WLL is giving a daily rain. The driver looks for a difference and adds the difference to the loop and sets the old value. 

Starting weewxd this counter is set to zero. But if there was rainfall all this rain is added again to the loop.

So e.g. if there was 2 mm of rain fell during the day, and after a restart, the driver adds this 2 mm to the loop (again), and is seen as new rain.

Is there a way to get this daily rain data from the database and set it in python as the starting variable?

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