Getting NMEA0183 Data onto OCPN -- My Experience

[Dockhead]

As we've discussed, it's a shame that OCPN doesn't speak N2K natively -- it would greatly simplify getting data into it. Although there are two mitigating factors: (a) you don't actually need that much data in OCPN (mainly -- position, heading, AIS); and (b) if you have a full-fledged N2K network, then OCPN is going to be a parallel or backup system anyway. Still -- I would really like it if OCPN's "dashboard" plugin were expanded and improved to display everything, and in different ways, and if we could get the rest of our data into it. I'm probably a small minority, though.

In any case, I have gradually succeeded in getting data into OCPN.

Already last year, I was getting AIS and position in by way of my black box AIS transceiver, which has a USB connection. I just hooked up the USB and it put its position data in, as well as AIS.

Now I've built another bridge from my network by connecting my PC to my nav table Zeus, by connecting the Zeus' NMEA0183 talker to a RS422 to USB adapter. This worked perfectly out of the box. The Zeus lets you configure what data is bridged onto NMEA0183, but this is, unfortunately, far less than what is available on the N2K network.

O, furthermore, happily takes both streams at the same time. How it chooses which GPS data to use -- when its getting it simultaneously from two streams -- I don't know. There's nothing like "instances" as in N2K. But in my case, it chooses the more accurate network GNSS receiver, rather than the built-in one in the AIS. Somehow.

[Opie91]

Why not use Maretron USB100? It is pretty much plug and play.

Maretron | USB100

[Dockhead]

Originally Posted by Opie91

Why not use Maretron USB100? It is pretty much plug and play.

Maretron | USB100

Because it's the same result, for 20x the cost?

[muttnik]

You can use connection priorities to say which source is preferred if you have the same sentence being produced from two sources.

IIRC from other posts you have the full-on GoFree thing. Would using data from the MFD over the network instead of via serial to usb adapter tidy up the wires at the chart table a bit?

[Neptune's Gear]

I'm just redoing my system today - changing from a laptop to one of NavAssist's PC's.

They have the Option of a built in NMEA2000 port!
However I already have that ability via a couple of Simnet AT10s. I was using a 4 port Serial hub to bring in all the data - but Howard's PC (NavAssist) has FOUR NMEA0183 ports, all Bi-directional, and can Use OpenCPN to multiplex anything.

So, I have GPS,AIS, Wind Instruments, Depth/Speed/temp, Autopilot (that also provides heading for the Radar overlays) and a Pactor all connected to the one PC.
Install has been straight fwd so far, just an issue with the radar to sort.
Oh yeah, the NavAssist PC also comes with wifi, set up with a Long range antenna for internet connection, AND an internal Wifi Intranet for the boat and mobile devices. Pretty cool and low cost. NavAssist are a sponsoring vendor on here!!
OpenCPN is my primary Nav tool.

[Dockhead]

Originally Posted by muttnik

You can use connection priorities to say which source is preferred if you have the same sentence being produced from two sources.

IIRC from other posts you have the full-on GoFree thing. Would using data from the MFD over the network instead of via serial to usb adapter tidy up the wires at the chart table a bit?

Hi thanks -- that clears that up (about connection priorities).

Concerning GoFree -- unfortunately there is no wired connection. I would have to connect by Wifi, and I need that connection for internet.

[Opie91]

Originally Posted by Dockhead

Because it's the same result, for 20x the cost?

Its $229 at Defender and gives you direct access to the NMEA2000 network thru a USB. It will also let you calibrate and update all of your Martron stuff with a PC.

You can also get a DSM250 simulator up on the screen also using the N2KAnalyzer software(which is free with USB100).

[sea-bee]

Originally Posted by Opie91

... using the N2KAnalyzer software(which is free with USB100).

Is the USB100 worth the money just for the analyzer? It looks like a useful tool for examining the network traffic in the event of bugs (such as the initial problems we have read about on some recent Navico installations)

[muttnik]

Originally Posted by Dockhead

Concerning GoFree -- unfortunately there is no wired connection. I would have to connect by Wifi, and I need that connection for internet.

There's a couple of Interpretations of that statement, both of which ultimately hint to me that you can't connect to your boat data *and* the Internet at the same time (do please jump in if I've got this wrong). I encountered a setup like that on a brand new Allures last year: Fantastic selection of GoFree/B&G kit plus a Bullet, but not set up so the owner could access the Interenet *and* the boat from the iPad at the same time. Marine electronics installers, in my experience, are great with traditional marine electronics but not always quite so great at IP network topology.

So if I have got that right...options? Obviously do what you do now is one. Second easiest is to plug in a secondary usb wireless dongle into the laptop. Small unobtrusive ones are cheap. Bring up one Internet interface on the laptop and the secondary on your boat data network. Doesn't solve the problem for iPads etc you might have, so that's a problem of connecting the boat network to the Internet. Is that a good idea? I was reading on panbo how navico are talking about doing online content for their MFDs so it's the way of the future. It means you don't have to reassociate every time you switch between boat data and Internet. I've blogged before about how marine electronics companies do not seem to have security as their highest priority or competency (wonder if Navico still have those default passwords on their MFDs...) so you should trust their devices slightly less than you trust you smart TV (i.e. not at all) but as with dodgy home devices which prioritise functionality over security, you are to a certain extent protected by a simple NAT/firewall/router thingy.

If I was way off base in the initial supposition then apologies for the ramblings. If not...what does the topology look like at the moment?

[Opie91]

Originally Posted by sea-bee

Is the USB100 worth the money just for the analyzer? It looks like a useful tool for examining the network traffic in the event of bugs (such as the initial problems we have read about on some recent Navico installations)

It does give you access to the NMEA2000 network which is valuable. You will have to decide that on your own. Personally if that is all it did for me I would have probably not bought it.

My primary reason to buy it was so that other Maretron sensors on the network could be calibrated (and updated) without a DSM250(or 150). For that it works well, but I am also able to use all of the NMEA 2000 data with OCPN. As Dockhead stated above it is not cheap, but it does get the job done quite nicely.

[Dockhead]

Originally Posted by muttnik

There's a couple of Interpretations of that statement, both of which ultimately hint to me that you can't connect to your boat data *and* the Internet at the same time (do please jump in if I've got this wrong). I encountered a setup like that on a brand new Allures last year: Fantastic selection of GoFree/B&G kit plus a Bullet, but not set up so the owner could access the Interenet *and* the boat from the iPad at the same time. Marine electronics installers, in my experience, are great with traditional marine electronics but not always quite so great at IP network topology.

So if I have got that right...options? Obviously do what you do now is one. Second easiest is to plug in a secondary usb wireless dongle into the laptop. Small unobtrusive ones are cheap. Bring up one Internet interface on the laptop and the secondary on your boat data network. Doesn't solve the problem for iPads etc you might have, so that's a problem of connecting the boat network to the Internet. Is that a good idea? I was reading on panbo how navico are talking about doing online content for their MFDs so it's the way of the future. It means you don't have to reassociate every time you switch between boat data and Internet. I've blogged before about how marine electronics companies do not seem to have security as their highest priority or competency (wonder if Navico still have those default passwords on their MFDs...) so you should trust their devices slightly less than you trust you smart TV (i.e. not at all) but as with dodgy home devices which prioritise functionality over security, you are to a certain extent protected by a simple NAT/firewall/router thingy.

If I was way off base in the initial supposition then apologies for the ramblings. If not...what does the topology look like at the moment?

Thread drift is a natural part of any conversation, and this is especially interesting

AFAIK, there is nothing complicated or wrong about putting the Internet into your boat network. The GoFree module is just a fairly ordinary router, and Navico now even publish detailed instructions for using a generic router.

However, I just don't like the idea of any of that. First of all, radar puts quite a lot of data into the network, and surely there is a risk of bandwidth problems. The Navico router blocks radar and sounder data from going out over wifi -- I like that. It is also waterproof and robust and has the Navico Ethernet connectors. Worth every penny of the $200 it costs, in my opinion.

So I keep the navigation network separate from the regular network, which goes through a Huawei LTE router, and I have no desire to change that.

I don't use O for primary navigation, so I think I'm getting enough data onto my PC with my $5 RS422 adapter from the MFD so far.

Besides the nav table PC, I have two tablets I use for navigation (can you say "massive overkill"? ) -- one old IPlod with INavX and its own charts, and one new Sony Xperia which allows me to remotely control the helm MFD via GoFree. And maybe I will set it up to remotely control the nav table PC so I can use O from the cockpit. If I need to use the Internet underway from the cockpit (and there is a remarkable number of non-trivial reasons to do this), I can do it from one tablet while navigating from the other.

So I don't perceive it, in my particular case, to be a big problem having nav network separated from the regular one, and being unable to connect to both at the same time, and in my gut I feel like it must be far safer for the nav network not to be cluttered up with crap from the Interweb.


One thing I wish we did have, however, was a native N2K speaking app, besides N2KView, which ran on a PC, and which could be configured to display and log all kinds of N2K data in all kinds of different ways, including trend analysis. I might break down and buy the horrendously expensive N2KView for this. I have a 32" monitor on my salon forward bulkhead, connected to the nav table PC. I display the OpenCPN screen underway, and would love to have instruments (so far us the O "dashboard"). This is so cool -- you can see it from anywhere in the salon or galley and even through the companionway. I have wiring installed for an infrared camera on the mast, which can also be displayed here, if I ever get around to installing it.


Another fantastic app would be a powerful and flexible instrument display which would run on Droid and IThings. Then we could recycle obsolete tablets to use as additional instrument displays.

[Dockhead]

Originally Posted by Opie91

Its $229 at Defender and gives you direct access to the NMEA2000 network thru a USB. It will also let you calibrate and update all of your Martron stuff with a PC.

You can also get a DSM250 simulator up on the screen also using the N2KAnalyzer software(which is free with USB100).

This actually looks like a very cool device. It seems to combine the function of both different Actisense devices -- it puts N2K PGNs directly into your PC for those programs which can use it (unfortunately nothing in the world besides N2KView as far as I know), and it also does a very thorough translation of N2K PGNs to 0183.

So it's actually not that expensive for what it does.

I don't really need it, because I have a $5 RS422 converter which gives me all the 0183 data bridged from my nav table Zeus. It's not complete, but it's enough for my purposes so far. The Zeus will bridge MARPA sentences, by the way -- don't know if O is able to use that, though.

If I ever have N2KView or another program which speaks N2K natively, I have the Actisense NGT-1, which I bought by mistake, thinking it would give me 0183 sentences.


Thread drift, but I can't find anywhere what 0183 sentences are broadcast over GoFree, or how or where the conversion is done. I guess the Zeus MFDs bridge N2K data not only to 0183, but also to Ethernet, which is rebroadcast by GoFree. It must be an 0183 datastream in Ethernet produced by the MFD, because the GoFree module (Wifi1) does not do any conversions of anything.

All I know is that it works perfectly, plug and play, with INavX, feeding absolutely all possible instrument displays in that program.

[muttnik]

Originally Posted by Dockhead

However, I just don't like the idea of any of that. First of all, radar puts quite a lot of data into the network, and surely there is a risk of bandwidth problems. The Navico router blocks radar and sounder data from going out over wifi -- I like that. It is also waterproof and robust and has the Navico Ethernet connectors. Worth every penny of the $200 it costs, in my opinion.

So I keep the navigation network separate from the regular network, which goes through a Huawei LTE router, and I have no desire to change that.

Multiple tablets...OK I see why this is a non-issue for you :-). And I appreciate the concern to keep things separate. The sonar/radar thing should be a non-issue though: The same mechanism which keeps those data off the wifi *should* (in theory but I haven't got one to test) not put them out through any port where the wifi-1 hasn't seen a request for them, so it shouldn't clog up your WAN port. Moreover the radar/sonar data shouldn't be propagated across your LTE router, so no chance of it chewing up your Three/EE allowance. Keeping things separate *does* protect you from a future product you install deciding to automatically update itself over LTE. Having forgotten to re-set the option to NOT auto-download updates for OS X when I put a new disk in my macbook I'm painfully aware of that little gotcha this month.

A second USB wifi dongle (and the mini ones are so small they hardly protrude) might still be of interest for the laptop and GoFree data.

'fraid I don't know much about what's available for N2K over an IP network but have seen that the iPad app associated with the DMK box seems to do N2K-over IP instrument display

[Opie91]

Originally Posted by Dockhead

Thread drift, but I can't find anywhere what 0183 sentences are broadcast over GoFree, or how or where the conversion is done. I guess the Zeus MFDs bridge N2K data not only to 0183, but also to Ethernet, which is rebroadcast by GoFree. It must be an 0183 datastream in Ethernet produced by the MFD, because the GoFree module (Wifi1) does not do any conversions of anything.

All I know is that it works perfectly, plug and play, with INavX, feeding absolutely all possible instrument displays in that program.

More thread drift. If you are looking to put NMEA0183 out over wifi, I bought one of these:

NTWB1 (4800 baud rate)

Works great. You can change the baud rate to 38400 so AIS data can be sent out. I added an inline switch so the data source into the unit can be changed. Switch position 1 takes information from a Garmin chart plotter below (used for anchor alarm) to supply basic navigation data like GPS data and speed. Position 2 takes info from O which includes AIS and all environmental data. Did this so the ship computer did not have to be on if navigation data was wanted on a tablet or phone.

[Dockhead]

Originally Posted by Opie91

More thread drift. If you are looking to put NMEA0183 out over wifi, I bought one of these:

NTWB1 (4800 baud rate)

Works great. You can change the baud rate to 38400 so AIS data can be sent out. I added an inline switch so the data source into the unit can be changed. Switch position 1 takes information from a Garmin chart plotter below (used for anchor alarm) to supply basic navigation data like GPS data and speed. Position 2 takes info from O which includes AIS and all environmental data. Did this so the ship computer did not have to be on if navigation data was wanted on a tablet or phone.

Looks pretty good -- much cheaper than the Digital Yacht version. Besides that unit, however, you will need some way to get N2K data converted to 0183. My plotters do that, but only a limited number of PNGs, and no AIS.


For those who have a recent Navico plotter, however, the GoFree unit (or any generic router) connected to the plotter's Ethernet port. This translates much more -- including AIS.