NMEA0183 Furuno Sounder to Garmin Plotter

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Portage_Bay

Portage_Bay

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Anyone from the dark ages willing to help with NMEA0183 connections? I used to be OK with NMEA 0183 wiring but that was long ago in another lifetime. This will be one way. NMEA out will be from a Furuno FCV-620 depth sentences to a Garmin 1042. Yes, I want to use NMEA0183. The boat does not have NMEA2000 nor is it likely to. The transucer for the Garmin has died. I need depth to the Garmin from the Furuno.

If I'm understanding this correctly I will use one of the Furuno outputs, TD-A or TD-B. And one of the Garmin inputs, RxA or RxB

My confusion arises from the line in the Garmin chart that says Black is "Ground (power and NMEA0183)". That seems clear enough. What about on the Furuno end? My feeble memory says when I was doing NMEA0183 two way comms it took two wired.

Below is the connection chart for the Furuno
1715017403128.png

And the connection chart for the Garmin
1715017597605.png
 
Seems to me you'd use Furuno white as transmit pos (+) and blue as transmit neg (-)... connected to Garmin brown as receive pos (+) and violet as receive neg (-).

Can't remember if each unit gets power and ground from elsewhere, or whether they connect. If the latter, Furuno red and black to Garmin red and black, power pos 9+) and power neg (-).

I'm a lot hazy on it all, though, forgot everything I ever learned about 0183 (wasn't much) 100 years ago or so... and even then, I think the biggest thing I ever learned is that manufacturers picked whatever colors they pleased for whatever function they felt like... no standardization at all...

-Chris
 
Ranger,

Thanks for chipping in. Much appreciated. You and I are looking through a different lens. I'm not saying you're wrong and I'm right, simply trying to understand things. I interpret the Furuno chart as TD = Transmit and RD = Receive. "A" as one NMEA port and "B" as the other. Actually I think you may be correct.

NMEA0183 is old skool and the easy trouble shooting tools are gone. A low voltage LED across the connections flashing showed output or dead showed nothing. Fiddle with menus, settings etc to get the LED to flash. Then I hard wired to a 9 pin serial port to a PC running a terminal program to see if I had the polarity right. Recognizable NMEA sentences displayed on the screen meant I had it right. Gobbledygook displayed meant I had the polarity reversed. Brute force trouble shooting to be sure but it worked. And because these are low voltage, low current I/O as long as I didn't let bad setups last more than a few seconds no harm done. Now it's shooting in the dark to say the least. Now it's USB, WiFi or blue tooth. Plug and play it's called. Plug and pray I call it.
 
Portage_Bay said:
Thanks for chipping in. Much appreciated. You and I are looking through a different lens. I'm not saying you're wrong and I'm right, simply trying to understand things. I interpret the Furuno chart as TD = Transmit and RD = Receive. "A" as one NMEA port and "B" as the other. Actually I think you may be correct.
Click to expand...

Last year sometime, I connected our Furuno MFD to our old SeaTalk/NMEA0183-only Raymarine AP course computer. Turned out to be relatively easy since everything was in close proximity...

Anyway, that used a wire pair out from the Furuno into a pair of receive connectors on the Raymarine. Power was already sorted on each machine, so I didn't have to do anything about that...

-Chris
 
I dug up some old Furuno manuals from things I've installed. I don't see anything about dual NMEA 0183 outputs. I would have assumed the "TD-A" and "TD-B" were two possible NMEA Transmit channels, but now I'm thinking maybe they are "+" and "-". It seems odd they wouldn't label them that way. I suppose you could look for continuity to ground on "B." Continuity wouldn't prove much, but lack of it would prove this interpretation wrong.
 
Ranger58sb's post #2 is correct.

To the other question TD-A, Tx-A, TD+, Tx+ are all synonyms. Same for RD-A, Rx-A, RD-, Rx-. So "A" and "B" are the two differential wires for a single port, not different ports with different data.
 
Thanks all for the help. Twisted that is the way I'll start out.
 
You may also need to configure the interface on the Garmin side (mainly to ensure that it is using the correct 4800 baud rate).
 
It worked. Mostly. Using jumpers in case I had to reverse polarity or try a different pair the Garmin displayed digital depth. But when I made the "permanent" connections it failed. Either I didn't pay attention and reversed a couple or I have a bad connection. No matter, easy to fix and I know it works. Thanks all.

Sounder 1.jpg
 
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