Access to 0183 over tcp with service discovery?

[pekka-leppanen]

(Apologies for a duplicate question to Google Groups ... the people appear to be here :))

I have a basic (including 'sudo apt install libnss-mdns avahi-utils libavahi-compat-libdnssd-dev') Signal K server running on RPi, with working NMEA 0183 and 2k data connections.

I can listen its "Convert Signal to NMEA0183" output with my app at given TCP address and the default port.

I'd like to enhance my app to connect via Bonjour/DNS-DS, but cannot figure out how to configure SK server's '_signalk-tcp._tcp' and start running the DNS-SD. ' The 'dns-sd -B _signalk-tcp._tcp' shows no advertisements from the RPi.

The 'https://signalk.org/specification/1.5.0/doc/connection.html' is quite detailed on what needs to be in place, but not how to do this?

Any help is appreciated,
pekka

[sbender9]

[tkurki]

The server should be advertising both its Signal K and NMEA 0183 services by default.

Are there any errors in the log when the sk server starts?

There may be a bit of confusion here, there’s

• Signal K over tcp
• NMEA 0183 over tcp
• Signal K over websocket

If you are using SK ws is preferable to tcp, as usage is simpler (no subscriptions needed in simpler cases) and there are options for authentication and encryption.

[pekka-leppanen]

I am after the 'NMEA 0183 over tcp'.

The server log a lot "Cannot read properties of null (reading 'toFixed')" errors, otherwise just the "signalk:streams:tcp-data ..."
" ...
Dec 20 10:53:04 2023-12-20T08:53:04.454Z signalk:streams:tcp-data $SDDBT,,,,,,45
Dec 20 10:53:04 Cannot read properties of null (reading 'toFixed')
Dec 20 10:53:04 2023-12-20T08:53:04.465Z signalk:streams:tcp-data $SDDPT,,,7B
Dec 20 10:53:04 Cannot read properties of null (reading 'toFixed')
Dec 20 10:53:04 2023-12-20T08:53:04.476Z signalk:streams:tcp-data $SDMTW,,C1A $SDVLW,,N,6.7,N,18451.5,N,6.7,N78
..."

"$avahi-browse -d local _signalk-tcp._tcp" shows now advertised services.
I can read the data stream by bypassing DNS-DS and accessing the SK server with directly with the IP address:port .

Regards,
pekkal

[tkurki]

You want _nmea-0183._tcp then - as already indicated in Scott’s screenshot.