NMEA 0183

[matt1]

Hi All

I need some guidance with connecting NMEA!

I currently have Raymarine ST60 instruments mounted on deck in the hatch garage. This includes, wind, speed, depth etc and also an ST60 which repeats GPS data (btw, sog etc). I'm now installing a Garmin chart plotter adjacent to the st60 instruments and intend to install an AIS. The chart plotter has 2 wires that RX NMEA and 2 that transmit NMEA. I want the plotter to show AiS and have wind (and maybe other instrument data) Is it as simple as;

1) take the AiS NMEA out and connect to one of the plotter's NMEA rx (in) wires?
2) take a connection off the Raymarine st60 NMEA (out) and connect to the other rx NMEA (in) on the plotter?

If I'm right in the above assumptions, can I connect the AIS into the ST60 seatalk bus below decks and just have a single NMEA connection to the plotter from the sea talk bus? - will that carry all the NMEA instrument data, including a 3rd party's AIS?

And lastly, is there no negative return path with NMEA? Eg it is as simple as NMEA out to NMEA in, with no need for a return or "circuit"

Thanks all

Matt

 

[pvb]

NMEA circuits essentially require 2 wires. Which AIS and which Garmin plotter are you getting?

 

[wiggy]

Raymarine and NMEA 0183 do not talk to each other, afaik you need a little box to translate between the two systems.

 

[superheat6k]

Seatalk is a different signal format to NMEA0183, so you will need a convertor. My boat has ST50 instruments, which includes an NMEA0183 output from the tridata repeater, but for some reason Raymarine dropped this feature on the ST60 range.

If you can sort the NMEA0183 format here is a diagram of my interconnections including a Furuno RO4800 VHF / AIS.

https://www.dropbox.com/s/v5pzswohjeu71we/NMEA Connections Garmin - Radio Ocean - Sealtalk.pdf?dl=0

 

[pvb]

Seatalk is a different signal format to NMEA0183, so you will need a convertor. My boat has ST50 instruments, which includes an NMEA0183 output from the tridata repeater, but for some reason Raymarine dropped this feature on the ST60 range.

Not true, the ST60 Multi can output NMEA data.

 

[superheat6k]

Not true, the ST60 Multi can output NMEA data.

My suggestion was from a previous thread where I was castigated for suggesting this was possible when I did not realise my kit was ST50 not ST60. If ST60 does have an NMEA0183 output then great, if the OP has the right instrument.

 

[pvb]

My suggestion was from a previous thread where I was castigated for suggesting this was possible when I did not realise my kit was ST50 not ST60. If ST60 does have an NMEA0183 output then great, if the OP has the right instrument.

You can easily check on the Raymarine website.

 

[matt1]

Thanks for all the advice. I've just bought a garmin gpsmap 70s and I'm likely to buy the McMurdo AIS. I currently have a Smaller and older Garmin GPS (450) at the chart table and that is connected to a std horizon vhf (shares posn data) and I'm somehow getting gps data from the existing garmin into the Raymarine circuit as its repeating on the st60 repeater.

 

[Pye_End]

And lastly, is there no negative return path with NMEA? Eg it is as simple as NMEA out to NMEA in, with no need for a return or "circuit"

0183 commonly uses the power negative as the NMEA negative - ie you may well connect up a red, a black and say a blue. Red and black for power - black and blue for 0183.

 

[Plevier]

Q1 - in principle you should be able to feed the AIS straight into the plotter. It may be 2 wires or it may be just one and ground; depends on the particular units.
Q2 - The ST60 Multi (is that what you have to repeat GPS etc as you say?) and Graphic instruments do have an NMEA output of a sort but not to correct standards. I think those are the only ones that do, not the wind, log or tridata.
It will work with a device that has a genuine isolated differential input, but not one with a single ended input referenced to ground. That is what my Garmin 750 had, I don't know if later ones are the same or if Garmin have cleaned up their act.
If your plotter is a single ended input, refer to this thread http://www.ybw.com/forums/showthrea...l-NMEA-to-Single-Ended&highlight=differential
You need an interface. Nigel has done it with a nice little circuit board, I did it more crudely for about 75p (and I have some spare sets of bits )
What you don't need to do is look out for one of Raymarine's £100 interface boxes.

 

[temptress]

Hi All

I need some guidance with connecting NMEA!

I currently have Raymarine ST60 instruments mounted on deck in the hatch garage. This includes, wind, speed, depth etc and also an ST60 which repeats GPS data (btw, sog etc). I'm now installing a Garmin chart plotter adjacent to the st60 instruments and intend to install an AIS. The chart plotter has 2 wires that RX NMEA and 2 that transmit NMEA. I want the plotter to show AiS and have wind (and maybe other instrument data) Is it as simple as;

1) take the AiS NMEA out and connect to one of the plotter's NMEA rx (in) wires?
2) take a connection off the Raymarine st60 NMEA (out) and connect to the other rx NMEA (in) on the plotter?

If I'm right in the above assumptions, can I connect the AIS into the ST60 seatalk bus below decks and just have a single NMEA connection to the plotter from the sea talk bus? - will that carry all the NMEA instrument data, including a 3rd party's AIS?

And lastly, is there no negative return path with NMEA? Eg it is as simple as NMEA out to NMEA in, with no need for a return or "circuit"

Thanks all

Matt

So as with many interfacing question here the answer is yes but...

Firstly let's assume your instrument accept NEMA 183 in (and your ST60 multi should). This is at a baud rate of 4800 (speed). Now AIS works at a much higher (38400) rate than this - so you need to change the AIS rate down - not usually possible on most cheap AIS sets, speed up the NEMA in (not possible the ST60 I think), get a converter, a multi-plexer or use a spare port on the plotter.

What model Garmin do you have? Most plotters have more than one input port these days.

If this is Chinese to you the we can work though it but t will take time. Otherwise maplin/e-bay are your friends here.

 

[matt1]

Thanks for this. The plotter's the garmin gpsmap 70s and has two NMEA out and two NMEA in wires and also a grounding point.

It's sounding like it should be fairly straightforward to get the ais to it but maybe not so easy to get the wind data. I'd like to get wind data to the plotter as I like the idea of the lay line feature. Data must be coming out my wind instrument as it feeds to the st4000 pilot for "steer to wind" functionality? But it doesn't sound like you think this will work on the plotter

 

[pvb]

Thanks for all the advice. I've just bought a garmin gpsmap 70s and I'm likely to buy the McMurdo AIS. I currently have a Smaller and older Garmin GPS (450) at the chart table and that is connected to a std horizon vhf (shares posn data) and I'm somehow getting gps data from the existing garmin into the Raymarine circuit as its repeating on the st60 repeater.

OK, the Garmin 70s has 2 NMEA inputs. You need to connect the AIS + output to the Garmin's brown wire (Port 1 input) and the AIS - output to the Garmin black wire. Then you need to connect the NMEA + output from your ST60 to the Garmin's violet wire (Port 2 input) and the NMEA - output to the Garmin's black wire. Then you need to go in to the Garmin's communications settings menu and set Port 1 to receive at 38400 baud, and Port 2 to receive at 4800 baud.

 

[Plevier]

Then you need to connect the NMEA + output from your ST60 to the Garmin's violet wire (Port 2 input) and the NMEA - output to the Garmin's black wire.

I agree the rest of your post but I can promise you this bit will not work because of Raymarine's non-standard output signal. Been there, done that, took several hours to get to the solution. See post #10 in this thread! (It would work with a device with a proper differential input but as you describe the Garmin, it appears they are still using a single ended input the same as I had to cope with on a GPSMAP 750.)

 

[pvb]

I agree the rest of your post but I can promise you this bit will not work because of Raymarine's non-standard output signal. Been there, done that, took several hours to get to the solution. See post #10 in this thread! (It would work with a device with a proper differential input but as you describe the Garmin, it appears they are still using a single ended input the same as I had to cope with on a GPSMAP 750.)

Well, it's probably best that the OP tries it himself first. Although you categorically say it won't work, you've already said that "I don't know if later ones are the same or if Garmin have cleaned up their act."

 

[Plevier]

Well, it's probably best that the OP tries it himself first. Although you categorically say it won't work, you've already said that "I don't know if later ones are the same or if Garmin have cleaned up their act."

Quite true I did say that but you subsequently said - having presumably checked - that the new Garmin takes its NMEA input between violet and black i.e. common -ve, the same as before.
This won't work.
The Raymarine output is a constant +11V on NMEA+ and NMEA- is floating and switches to ground for ON.
That will not work with any single ended input; all you are doing is applying a constant +11V to the NMEA IN.
You have to create a differential input as per the thread I linked to.
A suitable cct is in that thread.

PS I am not theorising; I have done exactly what the OP wants to do and have made it work.

 

[Billjratt]

I can endorse Plevier's information.
Just do what it says on the other thread and you will get data from the ST60 family displayed on the garmin (mine's a GPSMap 4008) no problem.
I can't offer anything on AIS though -don't need it up here yet...

 

[pvb]

Thanks for all the advice. I've just bought a garmin gpsmap 70s and I'm likely to buy the McMurdo AIS. I currently have a Smaller and older Garmin GPS (450) at the chart table and that is connected to a std horizon vhf (shares posn data) and I'm somehow getting gps data from the existing garmin into the Raymarine circuit as its repeating on the st60 repeater.

It would be worth investigating how the GPS data is getting in to your SeaTalk network, there may already be some sort of converter installed which could be useful to you.

 

[woolfie]

I know you didn't mention this in your confir, but do you have a Raymarine/Raytheon autopilot.

If yes, usually they have NMEA input and output... this is how my old MLR FX312 GPS was providing GSP data to the Seatalk Network.

 

[ianj99]

Well, it's probably best that the OP tries it himself first. Although you categorically say it won't work, you've already said that "I don't know if later ones are the same or if Garmin have cleaned up their act."

+1,

In reply to Plevier and Billjrat, I can't believe both Raymarine and Garmin have manufactured equipment that does not conform to the standard they have signed up to and paid NMEA.org to use. (Sounds to me like someone has connected an output to ground and blown it, hence it floats)

Has anyone simply tried reversing the output wires before connecting to the Garmin's input, it will not damage either devices?

http://www.navcen.uscg.gov/pdf/gmdss/taskForce/NMEA_7.pdf