Signal K not translating Seatalk 1 LOG datagram
Hi everybody. I am very happy with my Signal K setup. It gets almost all the data from the Seatalk 1 bus through a MacArthur HAT connected to a Raspberry Pi5.
With ALMOST I mean that the navigation.log Path shows a NULL value instead of 7364 NM that is the value displayed in all the Seatalk 1 instruments on board.
In the Seatalk connection log if a try to find the datagram 25 (according to the Thomas Knauf guide, 25 is the datagram id for the log data) I only find this:
1746468121658;N;$STALK,25
with no further data...
The two next data lines on the log are:
1746468121658;N;$STALK,F9
1746468121680;N;$STALK,FF
Does anybody else have the same problem?
Thank you.
3 Replies
I am no seatalk expert, but afaik there should be data after the prefix where there is none
See https://github.com/SignalK/nmea0183-signalk/blob/master/test/seatalk.js#L136 for how the data should look like
GitHub
nmea0183-signalk/test/seatalk.js at master · SignalK/nmea0183-signalk
NMEA0183 to Signal K parser. Contribute to SignalK/nmea0183-signalk development by creating an account on GitHub.
I agree, but data must be there (in the Seatalk bus) because the Seatalk instruments are able to use it. The question is why Signal K is not reading/using/logging it?
After many tries I believe I have a clue... If Signal K is active BEFORE I power up the Seatalk 1 system, then it reads and logs a nice 25 datagram with proper data.
After this moment - with the boat in the mooring - there are no meaningful 25 datagrams in the stream. At least for a long time.
Maybe Seatalk 1 sends "new" 25 datagrams only when there is a change in the value?
Yes, that seems to be what is happening. If I move "by hand" the paddle wheel of the speed sensor after a few seconds it triggers a new proper 25 datagram in the stream.