Using Signal K to modify NMEA data/sentences

[SirReal]

Hi folks!

I want to change some NMEA 0183 data and I did it with Node-RED. Know I am thinking about using Signal K but I am not sure if it is possible to modify data. I saw this thread:

https://forum.openmarine.net/showthread.php?tid=3809

But there is no answer to the question which was raised at the beginning.

I need to change a NMEA0183 MWV sentence and convert it to a NMEA0183 VWR sentence. Both contain wind information.

VWR is "relative wind angle". MWV is "wind angle" which seems to carry both, true and relative wind angles. In my case it is the relative wind angle but my autopilot only accepts VWR.

So, it is a simple conversion in this case. I can do it with Node-RED, I need to calculate a new checksum and send it out again. Okay.

But can Signal K modify sentences? 
I am also thinking about writing a plug-in for this special scenario. But before starting with that, I thought there might be something already which I can use.

Best regards, Malte

[PaddyB]

Hi folks!

I want to change some NMEA 0183 data and I did it with Node-RED. Know I am thinking about using Signal K but I am not sure if it is possible to modify data. I saw this thread:

https://forum.openmarine.net/showthread.php?tid=3809

But there is no answer to the question which was raised at the beginning.

I need to change a NMEA0183 MWV sentence and convert it to a NMEA0183 VWR sentence. Both contain wind information.

VWR is "relative wind angle". MWV is "wind angle" which seems to carry both, true and relative wind angles. In my case it is the relative wind angle but my autopilot only accepts VWR.

So, it is a simple conversion in this case. I can do it with Node-RED, I need to calculate a new checksum and send it out again. Okay.

But can Signal K modify sentences? 
I am also thinking about writing a plug-in for this special scenario. But before starting with that, I thought there might be something already which I can use.

Best regards, Malte

If you have signalk apparent wind speed and apparent wind angle the signalk to nmea0183 should do it for you maybe?

https://www.npmjs.com/package/@signalk/s...veTab=code

[PaddyB]

Just had a play, if signalk receives this $IIMWV,000.0,R,010.6,N,A*3A
it creates 'environment.wind.speedApparent' & 'environment.wind.angleApparent'
then with the signalk to nmea0183 running and VWR selected over tpc port 10110 it outputs >

$IIMWV,000.0,R,010.6,N,A*3A
$IIVWR,0.00,R,10.60,N,5.45,M,19.63,K*47

[SirReal]

Cool, thanks PaddyB! I will give a try!