OpenCPN with Garmin GHC 20 autopilot

[tjb1982]

Hello! I'm trying to figure out how to interface OpenCPN's route manager with my boat's autopilot setup. Does anyone know whether the Garmin GHC 20 is known to work in conjunction with OpenCPN via a NMEA 2000 USB Gateway?

I have a Garmin GHC 20 autopilot remote and a Maretron USB gateway. The Maretron is recognized as an available NMEA 2000 device by the GHC 20 (per the GUI on the remote itself). And I'm able to see NMEA 0183 sentences (input and output) from the debug window. I'm specifically seeing the following outgoing messages in the debug window:

$ECRMB, $ECRMC, $ECAPB, and $ECXTE

I'm getting 1 Hz GPS data from my phone (via a TCP network connection) and I can see that in the debug window, too.

So all signs would seem to indicate that the NMEA 2000 network is online, assigning "addresses" to devices (or something along those lines), that data is coming through the USB gateway to OpenCPN in 0183 sentences, and OpenCPN is attempting to transmit 0183-style sentences to the Maretron. However, the GHC 20 does not report receiving waypoint data and so won't allow "follow route" mode.

Does anyone know whether the GHC 20 is known to work in conjunction with OpenCPN? Does anyone have experience with the Maretron in this context? This setup was built for my dad in recent years to use with Windows and Coastal Explorer (and I've personally witnessed it working), but he has become mentally disabled and his CE software is unavailable at this point.

FYI, I'm running Arch Linux and a version of OpenCPN compiled from the latest github/master.

[rgleason]

Garmin GHC 20 is known to work in conjunction with OpenCPN via a NMEA 2000 USB Gateway?

Opencpn speaks only nmea0183, get something like an Artisense converter. See the Sup Hardware manual.

OpenCpn will send an active route to an autopilot using Nmea0183 sentences

Study Connections section

Read more in Sending an Active Route to an Autopilot
in Options > Data Connections (at the bottom) for more information about connections and testing.
Note that a Connections Output Port must be configured to send ECRMB, ECRMC and ECAPB NMEA sentences to the Auto Pilot.
Also read about the Activate Route & Active Route Console and Active Route Console Window - Showing Active Leg Data in Marks and Routes towards the bottom.


Help us by writing up your experience to be added here.

[tjb1982]

Originally Posted by rgleason

Opencpn speaks only nmea0183, get something like an Artisense converter. See the Sup Hardware manual.

I mentioned the Maretron unit. It's my understanding that this is functionally equivalent to the Actisense gateway.

[rgleason]

It is probably Nmea2000 you are seeing. I had an artisense showing in the Opencpn > Settings > Connection > Nmea Debug Window (Very useful) and it was scrolling text and stuff, but it was at 38,400 baud! I finally realized that O was viewing Nmea2000. The Artisense was reconfigured (it wasn't my job that time) with jumpers and the next time I was on board O Nmea Debug window had all the regular Nmea0183 and it ran beautifully for the next 10 days.

So look at the Connections > Nema0183 debbug window. Then look at the O manual if there is no data stream getting there.

You'll have to get and install a mareton driver for your OS is it USB? then to a Com port and then figure out which com port to set Opencpn to. It may be a little different than the Artisense experience.... but it was quite painless.

Have you loaded a driver? How is it connected? If you are trying to connect 2 devices to the one COM, it won't work.

that data is coming through the USB gateway to OpenCPN in 0183 sentences, and OpenCPN is attempting to transmit 0183-style sentences to the Maretron. However, the GHC 20 does not report receiving waypoint data and so won't allow "follow route" mode.

You'll need to look at the O manual for the detail how to configure your sentences. Make sure you did that. And also make suree you see the sentences going out in the O Nmea debug window!!!!

I'm specifically seeing the following outgoing messages in the debug window:
$ECRMB, $ECRMC, $ECAPB, and $ECXTE

Ah, sorry. Are they going out?

Does the Autopilot have a nmea0183 connection IN?
Does the GPS info show?

[rgleason]

data is coming through the USB gateway to OpenCPN in 0183 sentences, and OpenCPN is attempting to transmit 0183-style sentences to the Maretron.

So you have instrument data showing in the Dashboard? and the Boat position is correct and the boat is RED?

Sorry but there isn't enough info here, event though you did a good job describing it. We need to know step by step what you ahve done..and achieved.

We don't know if GHC20 accepts these sentences. Please let us know what you find out from the manf.

[rgleason]

https://support.garmin.com/support/m...=en&country=US

Garmin Nmea2000 manual has XTE number for crosstrack. That is essential.

Is it being converted by your mareton properly?

1. Make sure the sentences are going out of Opencpn, and that you are getting Instrument data from the Nmea2000 bus into Opencpn to show boat position (red) and other instruments. Then you know the connections are working.

2. Then you need to fine tune things, probably at the Mareton, setting it up to translate the sentences properly using the proper PGN.

I've never done that before. Never had to.

[tjb1982]

Originally Posted by rgleason

Ah, sorry. Are they going out?

Does the Autopilot have a nmea0183 connection IN?
Does the GPS info show?

Yeah, I saw the GPS signals incoming, and those EC* signals I mentioned above in the debug window in blue, marked "Output Message" -- the Garmin GHC 20 does not (to my knowledge) "speak" 0183, but that's why I have the Maretron. The spec for the Maretron is here; page 33 specifically describes the translation from 0183 to 2000.

[rgleason]

Just noticed that XTE was only Tranmit.

Good abbout the Debug window!!!!

[tjb1982]

Originally Posted by rgleason

https://support.garmin.com/support/m...=en&country=US

Garmin Nmea2000 manual has XTE number for crosstrack. That is essential.

Is it being converted by your mareton properly?

1. Make sure the sentences are going out of Opencpn, and that you are getting Instrument data from the Nmea2000 bus into Opencpn to show boat position (red) and other instruments. Then you know the connections are working.

2. Then you need to fine tune things, probably at the Mareton, setting it up to translate the sentences properly using the proper PGN.

I've never done that before. Never had to.

Okay. Thank you for helping me troubleshoot this. I'll try this out again tomorrow and report back.

[rgleason]

In the Garmin Nmea2000 manual
I see Transmit 129283 and 129284 but no recieve!
Find out about that I think.
Sorry.

PS: Good news I was looking at the part for Garmin Chartplotters, so yes they transmit that!
So the autopilot darn well should receive it.

I am afraid you'll have to go step by step, but it sounds to me like you've almost got it.
You need to know more about the Mareton if you are getting instrument data to Opencpn and back out.

[hoolie]

Originally Posted by tjb1982

Okay. Thank you for helping me troubleshoot this. I'll try this out again tomorrow and report back.

If it has worked with Coastal Explorer then your Maretron gateway must be translating correctly. Have you tried OCPN outputs with and without checksums or at different baud/data rates?

[rgleason]

Good point Hoolie. tjb sorry about your Dad.

[tjb1982]

Originally Posted by rgleason

Good point Hoolie. tjb sorry about your Dad.

Thanks, rgleason

[tjb1982]

Originally Posted by hoolie

If it has worked with Coastal Explorer then your Maretron gateway must be translating correctly. Have you tried OCPN outputs with and without checksums or at different baud/data rates?

I haven't tried every combination yet, but I have tried a few. I'll try and run through them systematically and see what I find.

Also, maybe the RMB sentence is incomplete/malformed for the conversion described by the Maretron documentation? The sentence coming from the debug console is:

$ECRMB,A,0.000,R,,NM001,2714.427,N,08018.831,W,0.1 48,166.032,0.000,V*2E

[tjb1982]

Here is the mapping from 0183 RMB to 2000 PGN 129285. It seems a little fishy to me because it doesn't map the N/S or E/W part of the Lat/Lon.