Wireless NMEA2000 Data in to OpenCPN

[Paul_DY]

Helped a customer today setup OpenCPN to use Wireless NMEA2000 data on his Mac. Actually remembered to take some screen shots and notes on what we did and I have posted a short article about this - hope you find it interesting.

Wireless NMEA2000 on OpenCPN | Digital Yacht Ltd

[bcn]

Paul,

what about a (Ethernet) cable option for those of us that don't trust the wireless stuff that much?

(and perhaps updating your web page of the Wireless NMEA2000 data in order to show that O is tested with it as well?)

Hubert

[CarCode]

Hubert,
there is no problem with WiFi on board.
I have installed the Miniplex-2wi from Shipmodul for a neighbor in the marina and so he is able to connect several computers to his instruments either with NMEA2k or with NMEA0183 at the same time for OpenCPN and other navi software on his iPad.
As you might know the iPad has no ethernet connector. It is also annoying to handle a laptop with cables attached.

Gerhard

[Paul_DY]

Gerhard is right about the cables being a pain on a lot of boats, but we have sold an NMEA0183 to Ethernet product in the past and if someone was particularly set on an NMEA2000 to Ethernet solution, I am sure we could be persuaded to supply one.

I have updated our website to show that NavLink works with OpenCPN.

Regards

PAUL

[NahanniV]

Is there a document that shows exactly what NMEA2000 PGNs are converted to what NMEA0183 sentances by this device ?

[MarcHall]

Originally Posted by NahanniV

Is there a document that shows exactly what NMEA2000 PGNs are converted to what NMEA0183 sentances by this device ?

Paul

Is your device converting PGN's to NMEA183 sentences or delivering PGN's to OpenCPN and OpenCPN now has the ability to parse out and handle the PGN's.

If it does directly send PGNs to OpenCPN, can it handle PGN's generated by OpenCPN and put them on NMEA2000 network ?

I would assume any PGN support in OpenCPN has been reversed engineered and it could lead down the path that properitary PGNs used by manufactures couild also be reversed engineered and added to OpenCPN.

As an example I have NMEA 2000 network of B&G instruments, 3 B&G Tritons and a NMEA183 to NMEA2000 converter that puts my older Garmin chartplotter GPS data onto the NMEA2000 network. I would like to add a Maretron fuel level indicator to the network but was sort of put off by that fact that without a Maretron display to configure the fuel level indicator via proprietary PGNs all I would see on the display was inches of fuel in the tank rather gallons. If the OpenCPN and your device allows OpenCPN to put PGNs on the NMEA2000 then this potientially provides a way to configure the fuel level indicator without a Maretron display or Maretron PC software.

Regards

Marc Hall
Crazy Fish - Maintaining, Upgrading and Sailing a Crealock 37

[Paul_DY]

I do have a document that shows the PGN to Sentence conversions and I was just going to post it but note it is a little out of date, please give me a little bit of time to update it, check it with our engineers and I will post it on this thread ASAP.

[Paul_DY]

Hi Marc,

Our NavLink converts from PGNs to NMEA0183 sentences that are then transmitted wirelessly to OpenCPN via a TCP/UDP network connection. This is the only way to realistically handle this on a PC/Mac/Linux computer, as there is no wireless NMEA2000 protocol currently defined and no computers have the CAN bus hardware interface that NMEA2000 is based on.

It would be possible for the OpenCPN developers to support one of the NMEA2000 gateways like the NGT-1 from Actisense or the Gateway from Maretron, but each gateway uses its own proprietary library to pass the PGN data to the application, so it would take quite a lot of time and effort to support these gateways in OpenCPN.

The downside of our NavLink method is that not all PGNs are converted and so things like Engine Data would not be transferred. That said, all of the popular GPS, Instrument (speed, depth, wind, etc) and AIS PGNs are converted and this is what most people want and what the current OpenCPN application and plugins support. Also any autopilot data that OpenCPN outputs should also be converted to drive an NMEA2000 autopilot, although I have not personally tried this yet.

For the time being, I think that NavLink provides a pretty good method of connecting OpenCPN to an NMEA2000 network.

Hope this answers your question.

[simonpickard]

Very cool.

I know this might go against your product. But I already have goFree installed on my yacht. Could I get this to broadcast to OpenCPN in roughly the same way?


Regards,
Simon

[Paul_DY]

GoFree is the wireless interface for the latest generation of Navico (Lowrance, Simrad and B&G) products. I have never played with one but I know they do send wireless NMEA data out that OpenCPN should be able to read.

[muttnik]

Originally Posted by simonpickard

I know this might go against your product. But I already have goFree installed on my yacht. Could I get this to broadcast to OpenCPN in roughly the same way?

There are two ways to parse that question. I am assuming that "this" applies to GoFree and "same way" means "like the DY product" rather than the other way round (correct me if I'm wrong).

The strict answer to the question is "no". GoFree doesn't do broadcast (i.e. sending out data in discrete packets which are available to any device which care to listen for them) but that's just being picky because the answer to the question "Can I get GoFree to supply OpenCPN with data?" is "yes" and the average user won't care about how it does it differently.

"GoFree"'s "tier 1" data is simply NMEA-0183 over TCP. As navico imagine it, client software would listen for service announcements (Bonjour or Navico's own service announcement protocol) and connect to a GoFree data source without the user having to tell their software how to find it. OpenCPN, like most non-navico software, doesn't do that but you can still set up a tcp data connection by getting the MFD to tell you its IPv4 address (which sadly might theoretically change as it is dynamically assigned). How to get the Zeus to tell you its address is in the manual. There's probably a list of PGNs which are converted somewhere, but not owning one I haven't looked.

What's better? Whatever you already have of course, by a country mile. Having said that, people setting up a data connection for broadcast UDP don't have to worry about a data source address and as I've argued before broadcast UDP is possibly a more appropriate way of distributing NMEA-0183 over IP in this context than TCP. Multicast UDP, which OpenCPN supports but few other things do, is ideal.

[CarCode]

I have only experience with the Miniplex-2wi from Shipmodul. This device can only connect to one computer with TCP but up to 7 computers with UDP.

All of the manafacturers however keeps it to their secret which PNGs are translated to NMEA0183 and which not. As you well know OpenCPN accepts only NMEA0183.
So to compare these devices one have to find out it by himself. That is the real problem...

Gerhard

[muttnik]

Originally Posted by CarCode

I have only experience with the Miniplex-2wi from Shipmodul. This device can only connect to one computer with TCP but up to 7 computers with UDP.

The "7 computers" limit, from a look at the manual, seems to be down to the number that the 2wi's dhcp server supports. Broadcast UDP data by its nature is available to every computer on the network. The "one tcp client" thing seems to be quite common in these kinds of devices but is, imho, questionably simplistic programming given the cost of these things. I stand to be corrected but I believe that Navico have implemented a concurrent tcp server in their GoFree MFDs, so multiple clients can connect over TCP simultaneously.

[simonpickard]

Another two question about this..

1. Could your user SEND routes to the GPS via this wifi NMEA2000 link? That would be amazing. Or is it only 1 way.

2. Is there any way to send radar info over WIFI NMEA2000 to OpenCPN (Mac)?

Regards,
Simon

[Paul_DY]

Hi Simon,

To transfer routes and waypoints, NMEA0183 uses the following sentences WPL and RTE, neither of which are converted by our NavLink. I have checked the Actisense Gateway and this also does not seem to convert these, not sure about the Maretron gateway.

If by radar data, you mean the actual radar scan then even NMEA2000 does not transfer this data. The only radar data that NMEA0183 and 2000 can transfer is the MARPA target data which is basically a range and bearing to whichever MARPA targets you are tracking on your radar. MARPA is not that common on pleasure boats and our NavLink and the other gateways do not convert this data.

You can get radar scan data in to OpenCPN by connecting a Garmin or Navico radar scanner to your computer via an Ethernet (network) cable.