Barometer reading in OpenCPN not working

[Rooney]

Hello!

I'm using OpenCPN 4.4.0 on Windows and I want to use the dashboard to display the barometer reading of my weather instrumment.
Unfortunately it does not show anything. Temperature is working, but not barometer.
Which NMEA messages are required?

The following messages are transmitted by my instrument:
$WIMHU,47.84,,,C*2C
$WIMTA,26.38,C*24
$WIMMB,27.98,I,0.9476,B*6F
$WIXDR,P,0.9476,B,barometer*25
$WIXDR,C,26.38,C,temperature*1D
$WIXDR,H,47.84,P,humidity*70

Regards,
Rooney

[rgleason]

I have several suggestions:

1. Confirm these nmea sentences are getting to OpenCPN by going to Options > Connections > and check "Show nmea debug window. Use pause to verify..

2. If opencpn is receiving the nmea sentences, record them to a file using VDR_pi. Save the file. This will allow you to test various configurations without having to be on the boat.

3. Read nmeaconverter documentation NMEA Converter | Official OpenCPN Homepage
it may allow you to change the sentence so that Dashboard sees it.

4. Search on this forum for barometer because I believe this problem was solved before.

5. Also check the Tracker records under closed items as there were several very informative Tasks about this specific topic during the solution.

[rooiedirk]

You have several different NMEA sentences with the same nmea-header. The Nmea- convertor can't see the difference between them, so that won't work.
As this problem seems to happen more, I might update the code to change this.
But that won't be in the near future. (Maybe somebody else can??)
Dirk

[rgleason]

So there would have to be a filter that would catch the P, C, or H and then convert it to a different sentence that works? Is this a standard sentence structure for XDR?

$WIXDR,P,0.9476,B,barometer*25
$WIXDR,C,26.38,C,temperature*1D
$WIXDR,H,47.84,P,humidity*70

It seems to me that someone previously solved this problem for barometer....
and it was the XDR sentence. I think you should do a search on the forum or in Tracker old tasks.

[stedy]

Dont think XDR sentence for barometric pressure is implemented. I know that MDA sentence was implemented some years ago.

[nohal]

Implementing the XDR sentence parsing to make everybody happy is somewhat problematic as it's format is highly vendor dependent = If we change the parsing to work with one instrument, it is almost certain we break it for another. No easy solution here, probably the best approach is to make the nmeaconverter plugin smart enough to handle this situation and write a bit of documentation...

Pavel

[rgleason]

Could he use nmeaconverter to make a MDA statement, if only he could filter it out using in this case, the second parameter...

[rooiedirk]

There are more sentences with XDR. NmeaConverter can't make a different between them.
You can make a MDA sentece, but that would jump between 0.9476 to 26.38 and 47.84. (pressure temp en hum.)
If there is a way to tell the instrument to only send pressure, you could use it.