NMEA 0183 AIS to MFD Wiring

TonyG13

Obtained an Em-Trak B921 AIS and will be connecting it to a RayMarine e97 MFD.

Have looked over the schematics and have a couple of questions about splicing between the two connections. The power and switch wires I understand.

It's the transmit/receive wiring between the two I don't want to screw up.

The AIS has NMEA Port 1 wires:

Brown - TX+
Blue - TX-
White - RX+
Green - RX-

The RayMarine NMEA Port 1 wires are:

Brown - TX-
Yellow - TX+
White - RX+
Green - RX-

What is the correct splice/connection to make it work?

LaRea

Guessing you connect the AIS transmit (TX) to Raymarine receive (RX).  So:

(edited for clarity!)

AIS                           Raymarine
----------------------------
brown TX+   --->    white RX+
blue TX-      --->     green RX-
white RX+    <---     yellow TX+
green RX-    <---    brown TX-

TonyG13

@LaRea - I had to stare at your plan for awhile, but I finally got the logic behind it! Thanks so much! 

LaRea

Yeah, I guess that was a bit cryptic!  I edited it.  You'll like having that stuff on the MFD.

TonyG13

LaRea said:

Yeah, I guess that was a bit cryptic!  I edited it.  You'll like having that stuff on the MFD.

You weren't cryptic at all! I always have had a hard time comprehending electronics diagrams. I'm great at architectural, plumbing, etc., - I was a facilities manager for years - but when it comes to electronics somehow I get brain freeze. 

Ian

Getting it wrong won’t damage it @TonyG13, you just won’t see data.

TonyG13

Ian said:

Getting it wrong won’t damage it @TonyG13, you just won’t see data.

Thanks @Ian - I just get nervous seeing this in bold on the install sheet: "Please check your wiring very carefully before applying power to the product. Failure to wire the product correctly could result in permanent damage."

They're probably referring to the power wires - which I know are the red and black and not getting those tied into the data wires. Hopefully I can't screw those up. :-)

TonyG13

Got everything pre-wired up as @LaRea suggested.

Went down to boat and pulled the MFD. A NMEA 0183 power/data cable was already hooked up with two of the above mentioned wires (brown and yellow) already in use. UGH!

Traced the data wires and they apparently go to the VHF radio as the GPS feed for the DSC/MMSI:

Raymarine MFD       Standard Horizon GX 1200

----------------------------

brown TX-   --->    green RX-

yellow TX+      --->     blue RX+

Baud rate for the VHF is specified at 4800.

So now I'm at a crossroads as to how to get data to/from the AIS at 38400 baud AND feed the VHF data at 4800 with the available wires.

The Raymarine cable only has the following available for use:

White RX+
Green RX-
Yellow TX+
Brown TX-
Orange/White RX+
Orange/Green RX-

Is it even possible to get both to work at the same time?

Or do I abandon the old VHF and get a new VHF with GPS built-in. (Winter project!)

LaRea

Dang, I didn't think of that.  The last time I wired a NMEA0183 system, I swore I'd never do it again because it's such a pain in the transom.  Replacing the VHF would definitely be the easy way to do it.  Then wire the AIS direct to the chartplotter.

Ian

If you love your current VHF you could try this https://www.aliexpress.us/item/3256802985716206.html?gatewayAdapt=glo2usa4itemAdapt&_randl_shipto=US

davidbrooks

Time for an upgrade. I would move to an nmea 2k network. 

TonyG13

It's a hybrid Raymarine SeaTalk/0183/2K system. I'm assuming based on how the wiring harnesses are cable tied together it was OEM from Rinker.

Looks like the only 0183 item is the feed from the MFD to the VHF for GPS. Everything else runs off the SeaTalk/2K network.

I did switch from a BoatUS MMSI to a FCC MMSI in case we ever did the Great Loop (or at least the Great Lakes) -- and I would need to swap to a new VHF anyway since that can't be reprogrammed.

@Ian's suggestion seems temping, but I'd rather a plug-n-play solution, so I think I'm going with a new VHF with internal GPS - which then frees up the slot for adding the AIS transceiver. Guess I have this year's winter project lined up!