Pi Trials and Errors

[John S]

Just a warning if you are considering putting a Pi online with an existing weewx system, it might not end well if there is competition for the dataset.

I have a Davis Vantage Pro 2 and I have been using an Ubuntu system to run weewx 4.2.0 via a Davis ethernet data interface. Reading in the weewx docs that running weewx along with other stuff on a PC can be problematic, and because my install is problematic, I decided to try getting a Pi 3 B up and running weewx.

I went through the system install and configuration so weewx would run and update the mariadb on the Pi. If the Pi was able to update the db correctly, I figured that's half the battle.

I glossed over the warnings about time on the Pi and didn't notice that the Pi was off by two hours vs my linux box.

... until I started getting this in my log:

Nov 16 12:45:28  weewx[37812] WARNING weewx.engine: Ignore historical record: {'windGust': 11.0, 'barometer': 30.083, 'lowOutTemp': 61.2, 'outHumidity': 61.0, 'interval': 15, 'forecastRule': 44, 'rain': 0.0, 'dateTime': 1605560400, ...  'windGustDir': 135.0}

Due to this, the old weewx on linux wasn't happy and wasn't updating interval data, it was in the error state and not able to reset.

I shut down the Pi but that didn't fix the issue so rebooted linux machine and that seemed to bring things back into sync, weewx is running and updating as before.\

I thought I'd share the fact that two instances of weewx hitting the same source hardware did cause things to lose their sync. I've nothing other than the log to point to the weewx driver setting the clock so if you have two systems with differing times, only one will win the prize.

So, it appears that you can bring a Pi online to run weewx, just don't expect it to share the hardware nicely.

[John S]

I see in the Davis trouble shooting guide (https://github.com/weewx/weewx/wiki/Troubleshooting-the-Davis-Vantage-station#corrupt-station-memory) mention of clock skew, which is what happened above. I just found a new way of doing an old trick!