Dashboard barometer reads 0, but La Crosse display OK

[AntSeiderer]

I have a La Crosse 2357 connected by USB adapter to a Raspberry Pi Zero running Cumulus MX build 3041.

The system has been working well for nearly a year, but 10 days ago all sorts of problems occurred at the same time, probably as a result of a power failure followed by low mains voltage once the power was "restored". One such problem is that Cumulus no longer recognises the La Crosse barometer. At first the La Crosse display was showing relative pressure of around 9950 hPa, so I thought I understood why Cumulus was unable to interpret this. On the La Crosse display unit, I changed the relative pressure to around 1015 hPa and rebooted everything, however Cumulus still reports 0 hPa, no matter what I try.

Other problems are:

1. FTP not updating. Website http://www.hillwoodhouse.com/weathermx/index.htm unchanged since 21 Oct. All .json files on FTP server dated 21 Oct. Realtime gauges working OK.

2. Wind speed not plotted on graph, but wind gust is.

3. Weather Underground feed https://www.wunderground.com/personal-w ... O2#history updating OK, except for pressure, which remains 0.

[steve]

In the latest diags file, your pressure offset is 8019.6. I haven't actually extracted the absolute pressure reading from the archive data bytes, but whatever value they contain, the result is going to be beyond the bounds of realistic pressures, so Cumulus is ignoring them.

Your other problems are knock-ons from this, as Cumulus is not doing timer-based actions because it hasn't had a valid pressure reading - see the FAQ: http://wiki.sandaysoft.com/a/FAQ#Cumulu ... eb_uploads

[AntSeiderer]

Thanks Steve, that figures, because I had to reduce the pressure displayed in the La Crosse unit by that huge amount, in order for it to display a reasonable relative pressure (around 1015, I think). Where, in Cumulus, do I correct this huge offset?

[steve]

I think I've just realised what's going on, it was the fact that your offset was just over 8000 that gave it away. Your offset is actually negative. The Open2300 site (where I got my La Crosse info from) doesn't make it clear that it can be negative. Perhaps no-one has ever seen it before, as normally a negative offset would mean you are below sea-level. In your case it would appear that your pressure sensor is reading far too high.

What you could do is adjust your relative pressure until the offset is no longer negative - it looks like adding about 180 hPa would do it. Then you could use the calibration settings in Cumulus to bring it down to the correct value again (if you added 180 on the console, you would use an offset of -180 in Cumulus).

It would mean that your console would display the wrong pressure, but Cumulus should have the correct figure - assuming your pressure sensor consistently reads too high by the same fixed amount.

[AntSeiderer]

Success!

I started reducing the pressure offset on the console, but it became too tedious. Each time I reduced the reading from 1900 odd to around 1015, the offset would reduce by around 1000. Since I had 8000 odd to get through, it was going to take a long time. Throwing caution to the winds, I did a factory reset on the console. Cumulus MX came up with all the data showing on the dashboard and a zero pressure offset. I recalibrated temperature and pressure readings, and now everything works perfectly.

Just one question: How do I determine or change the data update period on the console so that I can match it in Cululus MX station settings?

[steve]

Just one question: How do I determine or change the data update period on the console so that I can match it in Cululus MX station settings?

Sorry, I don't understand. You can't as far as I know change the update period on the console. You can't change it in Cumulus. If you mean the archive interval, then I can't help you as far as the console is concerned. If you do change it, bear in mind that the La Crosse has a tiny archive memory.

[AntSeiderer]

In Cumulus MX, under "Station Settings", there is a setting for log interval. values can be from 1 minute to 30 minutes, and the user is asked to set his station to the same. What should this be?

Under "Web/FTP settings" there are entries for upload interval and realtime interval. What should these be?

My La Crosse console receives its outside data wirelessly at present, but I will probably hardwire it in the near future.

Thanks for your assistance.

[steve]

The intervals in Cumulus are configurable so that you can choose whatever suits you. I can't tell you what to use.

With La Crosse stations, it's not critical for the operation of Cumulus that the logger interval of the station be set to the same as the Cumulus logger interval, and given that the station holds only a few entries, this can be hard to achieve anyway if you want to leave Cumulus not running for any length of time. I don't recommend setting it to more than 30 minutes, and definitely not more than an hour.

If you intend to run Cumulus pretty much all the time, then the console logger interval is not significant anyway - Cumulus only uses the console logger entries when it starts up, to catch up again.

[PaulMy]

In Cumulus MX, under "Station Settings", there is a setting for log interval. values can be from 1 minute to 30 minutes, and the user is asked to set his station to the same. What should this be?

Each person has their own preference and/or need, and also is hardware dependent.

I have my data logger (Davis) and Cumulus log interval both at 10 min.

Under "Web/FTP settings" there are entries for upload interval and realtime interval. What should these be?

I have my Cumulus upload interval to website at 5 min, and have selected realtime as well and this set at 8 sec.

Enjoy,
Paul