CWOP Error

[mike_b]

I seem to be having a problem uploading CWOP data since recently upgrading to Cumulus MX. Weather Underground data is uploading successfully with MX and the CWOP data was uploading from Cumulus 1.

This is the error:
2016-10-17 18:03:26.895 CWOP error: Value was either too large or too small for an Int32.

I attached the MXDiag file.

[steve]

You don't have debug logging turned on. You will need to turn that on so that the string being sent to CWOP is logged to the diags file.

[mike_b]

I attached the diags file with logging turned on.

[steve]

It's not getting as far as sending the data to CWOP; the error message is from an exception while constructing the string. It means that one of your readings has an unexpected value - unfortunately I can't easily say which, or why - it may be a bug in one of my conversion routines which for some reason only affects you. Do any of your readings displayed by MX look wrong? Do you have a solar sensor and are hence sending the reading to CWOP?

[mike_b]

I haven't noticed any unusual readings.
I don't have a solar sensor.
I attached a screenshot of my current readings.

[steve]

The problem appears to be in the altimeter pressure calculation. CWOP requires altimeter rather than sea-level pressure, and for Davis stations Cumulus uses the absolute pressure read from the LOOP2 packet and converts it to altimeter pressure using the altitude that you have set in Cumulus. Unless my arithmetic and byte counting is wrong, your LOOP2 packet contains zero for absolute pressure, which results in a negative value when converted to altimeter pressure. Perhaps this is a bug in firmware 1.90.

To check that this is correct, and as a work around, you could turn off the use of LOOP2 packets in MX. Stop MX and edit Cumulus.ini, and add a line to the [Station] section:

UseDavisLoop2=0

Note that this will cause MX to use sea-level pressure fro altimeter pressure - CWOP might notice this and get upset, depending on your altitude. But it will prove that the problem is as I suspect.

[mike_b]

UseDavisLoop2=0 appears to have fixed the problem. Data is now successfully uploading to CWOP. CWOP shows pressure of 1018.7 mb.