NMEA 0183 vs 2000

Storyline

Storyline

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Following on from my request for recommendations for a Class B AIS transceiver, it may be that the set I want only outputs in 0183. The plotter I want to connect it to (Garmin GPSMap 4010) supports both protocols but the main sort of hub that is connected is NMEA2000. Are there any disadvantages to using 0183 ?

Many thanks
Paul
 
Assuming that you already have an N2K bus (ie wires connecting all you NMEA 2000 equipment) to the plotter, the downsides of using NMEA-0183 are that you have to run an additional pair of wires to the plotter (which may or may not be any more difficult than connecting the AIS to the existing N2K bus) and you'll lose that NMEA-0183 port which maybe in future you'll wish you had for some other piece of NMEA-0183-only kit. Functionally it should be no different. The other possible problem with using NMEA-0183 is that the AIS output will only be available to the plotter (unless you run additional wires to other NMEA-0183 "listeners"). However, for most leisure boaters with a single plotter, that's all they need. If you're going to use a laptop which accepts AIS input, consider how else your AIS unit will output data. Via USB is ideal for most people these days. A 9-pin serial interface requires most people to buy a separate serial to usb converter. If it has neither (unlikely as a PC interface is usually required to enter MMSI tec.), NMEA-0183 tends to be significantly easier/cheaper to usefully hook up to a laptop than NMEA-2000.

EDIT: I should probably say that on my boat I have a plotter and AIS unit which do both NMEA-2000 (/seatalk ng) and nmea-0183. I have them connected via NMEA-0183 because they are the only two potentially N2K devices on board and I thought it would be easier to run NMEA-0183 between them (actually a 4 core wire as my potter talks back to the AIS) than mucking about with termination resistors etc. in creating a 2 node N2K bus. As I've said before, I'm still holding out for Onenet (or some future open source alternative :-)
 
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Thanks for the comprehensive reply :)

I already use the NMEA port on the plotter to send the position to the VHF. Can I just take the 0183 from the plotter to a junction box and then connect the VHF and AIS to that. ie connect both 0183 signals to the one input on the plotter.I realise the VHF is receive only and the AIS is transmit/receive.

I take it from your reply that there is no other benefits (speed, amount of data) of 2000, it is just a question that it is easier to connect. Is this correct ?
 
Storyline said:
Thanks for the comprehensive reply :)

I already use the NMEA port on the plotter to send the position to the VHF. Can I just take the 0183 from the plotter to a junction box and then connect the VHF and AIS to that. ie connect both 0183 signals to the one input on the plotter.I realise the VHF is receive only and the AIS is transmit/receive.

I take it from your reply that there is no other benefits (speed, amount of data) of 2000, it is just a question that it is easier to connect. Is this correct ?
Click to expand...
You can't connect two outputs to one input.
 
Storyline said:
Thanks for the comprehensive reply :)
Can I just take the 0183 from the plotter to a junction box and then connect the VHF and AIS to that. ie connect both 0183 signals to the one input on the plotter.I realise the VHF is receive only and the AIS is transmit/receive.?
Click to expand...

I tried to do this a couple of years ago with a Lowrance plotter, a NASA AIS receiver & a Mercury VHF. I found that I couldn't make it work because the AIS & the VHF required different baud rates (can't remember the details at the moment...). My solution was a cheap GPS receiver wired directly to the VHF & used the 0183 for the AIS, but I suspect if you have the option of 2000 that might be less hassle.
 
Storyline said:
I am confused now :). I assume what you are saying is that each 0183 device has to go to its own socket on the plotter ? In that way it is different from NMEA2000 which can be connected via one bus. Have I got it right ?
Click to expand...

Sorry, my last post made before reading the penultimate 2 posts. Yes, your assumptions are pretty much right.

NMEA 2000: Bus architecture: ie everything connected to one communications medium
NMEA-0183: point to point. Actually current version is point to multi-point. You can connect one "talker" (ie data transmitting port) to up to possibly 3 listeners, but a "listener" (ie data receiving port) can only "listen to" one "talker".
A "multiplexer" is a device which takes the application level data from (possibly) multiple electrical connections, then sends that combined (application level) information across one or more electrical connections. These can simplify your NMEA-0183 architecture, but they can cost a few hundred quid and IMHO if you have the option of NMEA 2000 you should take that rather than muck about with multiplexers

Certainly when you start connecting many devices, the NMEA-2000 architecture is the simpler option, but the "buy in" for the first bit of wire is more and not everything has an NMEA 2000 interfaces
 
laika said:
Sorry, my last post made before reading the penultimate 2 posts. Yes, your assumptions are pretty much right.

NMEA 2000: Bus architecture: ie everything connected to one communications medium
NMEA-0183: point to point. Actually current version is point to multi-point. You can connect one "talker" (ie data transmitting port) to up to possibly 3 listeners, but a "listener" (ie data receiving port) can only "listen to" one "talker".
A "multiplexer" is a device which takes the application level data from (possibly) multiple electrical connections, then sends that combined (application level) information across one or more electrical connections. These can simplify your NMEA-0183 architecture, but they can cost a few hundred quid and IMHO if you have the option of NMEA 2000 you should take that rather than muck about with multiplexers

Certainly when you start connecting many devices, the NMEA-2000 architecture is the simpler option, but the "buy in" for the first bit of wire is more and not everything has an NMEA 2000 interfaces
Click to expand...
Thanks, very clear, I understand.

If I have to buy a non 2000 AIS then I will have to wire the VHF to another GPS which was already on the boat when we got her. That way I will just have one 0183 device connected to the plotter.

Edit: actually, thinking about it, I have the old GPS wired to a navtex set which keeps a log of positions. Is it possible to connect the VHF to that signal ie both the VHF and the Navtex listening to the same signal ?
 
Storyline said:
Edit: actually, thinking about it, I have the old GPS wired to a navtex set which keeps a log of positions. Is it possible to connect the VHF to that signal ie both the VHF and the Navtex listening to the same signal ?
Click to expand...

If it's all RS422, the GPS has NMEA tx+ and NMEA tx-, and the navtex and VHF have nmea rx- and nmea rx+ then you're fine. I'm not an electronics expert though and I seem to remember some caveat about connecting multiple listeners to single ended nmea (ie tx, rx and power ground wires rather than pairs) which your old GPS and navtex might be. Not sure what the problem would be if all are sharing a common ground: any electronics folk here can tell us? I think you'd be fine but would probably like someone with more electronics knowledge than me to comment.

Note that what you might lose by not having the VHF connected to the plotter is that some VHFs output DSC info over nmea (e.g. position reports) which can then be plotted on a suitable plotter's screen.

Some AIS units do have an integrated multiplex to specifically allow connection of a VHF to a plotter, so that might be something to look at too (sorry to complicate things)
 
Your Garmin 4010 will have a number of NMEA0183 tx and rx ports. Use, say, port 1 for the vhf and then use port 2 for the AIS. Each port is capable of tx and rx so doesn't really matter which you use, although on some earlier plotters only one of the ports was high speed compliant.

Personally I would not buy anything which is not N2k now. I have the Digital Yacht AIT2000 and am very happy.
 
Storyline said:
The plotter I want to connect it to (Garmin GPSMap 4010) supports both protocols
Click to expand...

Storyline said:
I already use the NMEA port on the plotter to send the position to the VHF.
Click to expand...

Keith-i said:
Your Garmin 4010 will have a number of NMEA0183 tx and rx ports. Use, say, port 1 for the vhf and then use port 2 for the AIS. Each port is capable of tx and rx so doesn't really matter which you use, although on some earlier plotters only one of the ports was high speed compliant.
Click to expand...

Sorry: I had assumed from the second quote above that there was only one nmea-0183 port. Actually it seems there are 4 receiving ports and 2 transmitting on the 4100 so as Keith-i says there shouldn't be a problem: Wire the AIS to a separate receive port on the plotter, set the port type to "NMEA High Speed" (as the garmin manual says) and you're done. Or go N2K :-)
 
laika said:
Sorry: I had assumed from the second quote above that there was only one nmea-0183 port. Actually it seems there are 4 receiving ports and 2 transmitting on the 4100 so as Keith-i says there shouldn't be a problem: Wire the AIS to a separate receive port on the plotter, set the port type to "NMEA High Speed" (as the garmin manual says) and you're done. Or go N2K :-)
Click to expand...
Thanks Laika and Keith. I assumed the 4100 had only one 0183 input -should have checked -oops ;)

As said above, I am sort of stuck to buy the 0183 Comar as I have already installed the GPS & VHF antenna that they recommended.
 
I know the guys earlier have explained everything but just as an add on - The Garmin technical guys are very helpful on the phone or via email, should you need them. I use a 4010 with a Garmin AIS600 networked to it.
 
Had similar debate with myself when we did similar last year...a technical restriction on the hds plotter meant nmea183 ports could be low or high speed but couldnt mix tx/rx baud rates to support dsc and ais needs simultaneously. Since the plotter and vhf had n2k ports too the choice came down to adding a nmea183 multiplexor or a nmea183 to n2k converter. I settled on the latter as I figured that any future swap out is likely to be for a n2k device, less fiddly connections to make/break, similar cost and growing 2nd hand market for the converter should I ever sell it on and it freed up the nmea183 port to multidrop feed the gps output to the legacy yeoman chartplotter and bulkhead gps repeater display. Overall I'm pleased with the connectivity and futureproofness achieved.
 
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