Windchill data WMR200

[TingBrouwer]

The data displayed in cumulus (36 celsius)is must different then on the display (3 celsius) on the WMR200 console.
(calculation in Cumulus switch off)

is that correct ?


sorry for my poor Englisch

Recards

Gert Brouwer.

[steve]

Perhaps I've forgotten to convert from F (the WMR200 supplies wind chill in F for some reason). I'll check.

[steve]

There's a mistake in the (unofficial) protocol spec that I use. I can fix it, but until I do, you could perhaps use the Cumulus calculation instead.

[TingBrouwer]

Thanks for the quick response Steve, I'll use the "calculation" mode.


Gert

[mcrossley]

Presumably this ties in with this thread too?
https://cumulus.hosiene.co.uk/viewtopic.php?f=5&t=6366

[steve]

Presumably this ties in with this thread too?
https://cumulus.hosiene.co.uk/viewtopic.php?f=5&t=6366

Different weather station type, but as it happens it looks like I have decoded the wind chill incorrectly for the 88/100 also (my fault this time). It was never clear to me in that thread whether or not the console also displayed the weird values.

[steve]

Incidentally, your excellent WMR100 spreadsheet is missing the wind chill decode from the wind packet. It appears to be:

Wind chill in degrees F = ((256 * low nibble of byte 8) + byte 7) / 10

[mcrossley]

Ah, thanks, that is my task for tonight, and maybe add all the WMR200 decodes too.

Looking at my sample data it looks like:

Wind chill in degrees F = ((256 * low nibble of byte 8) + byte 7) / 10

should possibly be:

Wind chill in degrees F = ((256 * high nibble of byte 8) + byte 7) / 10

????
"00 48 0A 0C 25 00 00 00 20 A3 00"

The low nibble of byte 8 = 0, high nibble = 2

Or is the 'other' nibble used for something?

[steve]

Or is the 'other' nibble used for something?

Both the 100 and 200 have thresholds for when wind chill is available (I'm not sure whether they use the standard 10C/3mph values) and give a value of zero when wind chill is not available. When the value is zero, it looks like they may set that bit in byte 8 as well.

[ronholmj]

This probably explains my windchill readings (see windchill value in attached image). I've switched to using the calculated value (and also noticed that there is a new build that I will get around to installing).

Capture.JPG

WMR200 with Cumulus 1.9.2 build 1016 on Vista

Thanks - enjoying your product very much,
Jim

[Tonky]

It seems to work fine for me, I unchecked the 'calculate' option.
Normally it’s always checked.

[bard]

Hi,

Win 7, WMR200, v1.9.2 build 1029

Is there something wrong... the windchill temperature is warmer than the temperature...
I have now set the Calculate wind chill and the problem is gone... I also had to set Calculate dew point to get sensible dew point values.

temp.png

~b

http://heitmann.net/weather

[steve]

Is there something wrong... the windchill temperature is warmer than the temperature...

That's either:
1. A bug in the station firmware (you don't say whether the console displays the same anomaly), or
2. A mistake in the unofficial protocol spec that I've used, or
3. A bug in Cumulus (but I think my code now agrees with the unofficial spec)

I also had to set Calculate dew point to get responsible dew point values.

As I said earlier in the thread, the station reads zero when its dew point value is not available, but I don't know how it indicates that this is not a 'real' zero degrees.

Best to stick with the Cumulus calculations.

[Tonky]

I have been using the stations wind chill the last couple of months, and no problems.

[bard]

There is definitively something weird going on... Every time I switch of "Calculate wind chill", Cumulus is showing higher wind chill temperature than the station. Its raising about 5 Celsius deg.

I have attached the debug.log file if it helps... ??

Without "Calculate wind chill"
Outdoor: -13,5
Cumulus Wind Chill: 16,7
Station Wind Chill: -19
Wind: ca 2.5

With "Calculate wind chill"
Outdoor: -13,5
Cumulus Wind Chill: -20
Station Wind Chill: -20
Wind: ca 3.0

I have now restarted cumulus and the station(removed batteries)...
I am now doing some continuous testing/observing, trying to switch "Calculate wind chill" on and off...
It looks to me that more wind gives even more differences in in wind chill values compared with or without "Calculate wind chill" when I compare to the value the station is showing.

Hope this helps... If you need more debug information just tell me what to do...

~b