Tony - Is there a standard in NMEA 2000 for cha...
Is there a standard in NMEA 2000 for chartplotters for the update interval? I am sending pressure, humidity and temperature on a five second interval which seems to always show the last updated value. Never
--. On the other hand, I have freshwater level sending at at 100ms and sometimes ithe plotter stops displaying and shows -- for a period of about one or two minutes, then displays the value again. Same with engine parameters when at a 500ms interval, showing -- and then the value about every 10 seconds on and 10 seconds off. Is there a way to know how often to send an update so that the plotter only shows -- when Signalk no longer is getting updates from the sensor? I can probably write some logic to ensure there is exactly the interval needed but I would need to start with how often.8 Replies
It’s part of the n2k spec and is different for each pgn
Have you played with the resend settings in the plugin?
I am handling these in Node Red instead of the sk-n2k plugin. Do you have a link where I can see each PGN update interval?
The 100ms thing sounds suspect
I have the tank resend set to 1 second. And the Raymarine devices are fine with that.
The n2k spec is not public
I see some information about update interval in the Canboat project page. https://canboat.github.io/canboat/canboat.html#pgn-list
I don't need the spec. This is all just hacking, so trying to just get things to work 😎
Yes. Don’t know how accurate it is and it’s not there for everything.
It’s also hard to say if the manufacturers actually follow that…
It was trial and error for me to get them right.
a couple of the engine pgns are defined as fast dynamic updates… for these i suspect you probably need to be <500mS ..
( have a nagging memory ther are “10Hz rate” .. but i coulb way wrong..
also there are some gps related i recall are similar “fast uodare” tyoe
I cant test it at moment (very remote from my boat) .. but i recall that when you look at the n2k bus using an actisense or similar .. that it gives some clues about the “update rate” ..fir different pgns
I changed all of the input nodes in Node Red from subscription to interval, which works much better. I think the issue is that the subscription is not rapid enough updates.
I find that hard to believe…
Something else going on. I’ll try to do some testing this week…