Friday, 21 July 2017

OpenPlotter, NMEA data FROM file

          Updated 2018-02-01 !

To test Openplotter, (OP), together with OpenCPN,(OC), without connecting to the navigation network on board there are two features 
  • Using the NMEA generators, found in the OP "Tools" menu 
  • Use log files which are stored within the SignalK application.
The generators are explained in the documentation and here will be a description how to use the log files from OP 

Connect to the Rpi.

As said before SignalK, SK, is the engine in OP so we start with terminating that process so we can redirect SK to the log files.

Open a Terminal window "Application menu => Accessories => Terminal" and type 

pkill -f signalk-server

then start SK with the NMEA0183, N1, log file

cd .config/signalk-server-node

And something like this will appear

signalk-server running at
Error reading /home/pi/.config/signalk-server-node/public/mapcache

Leave this session running, start OP and check the N1 data with "OP => Signal K => SK Diagnostic".

Since You are not using KPLEX and the N1 output from SK is sent out as TCP on port 10110, You must add a new connection in OP; "Options => Connections => Add Connection" 
  • Network, TCP, localhost, 10110 and click on "Apply
Open OC and You will be sailing in the south of Finland with data from 


If You are more interested in NMEA2000, N2K, data, change 


above to


And now You will be using the data from 


Please note that if You want to see Your position in OC with this N2K sample file, it is a little more complicated since OC just can use N1 as input;
  • Enable/activate the SK plug in "Signal K to NMEA0183"
  • Mark the sentences You want to transfer
  • Add the new connection, mentioned above, in OC; "Options => Connections => Add Connection" 
    • Network, TCP, localhost, 10110 and click on "Apply"
  • Check Your position in OC
  • Go to the "Tools" Meny and click on "NMEA 0183 generator" and create Your own N1 sentences
  • Start with the RMC sentence where You pick the data from Signal K value
  • For example the Latitude value is populated from 
    • Signal K value
    • -- vessel(self)
    • -- group(navigation)
    • -- key(position.latitude)
    • -- format(lat:
  • Continue with all the values within the sentence and save it
  • Check the data You have created using tab "NMEA 0183" 
  • Mark the "system_b" row and click on "Diagnostic"
  • A new window will open showing the RMC sentence
  • Check Your position in OC
When You want to terminate the test environment, just restart the RPi.

And here a post how to record navigation data

No comments:

Post a Comment