Connecting different brands via NEMA 0183

I have a Raytheon RL 80RLC radar plotter installed in 1999. Supplying info to this MFD is a Autohelm heading sensor using the NEMA 0183 protocol. I recently installed a Garmin 740 plotter. The Garmin unit has 2 NEMA 0183 inputs and outputs. I have a Standard Horizon VHF with AIS which is connected to two of the Garmin outputs and one of the inputs.

I would like to supply heading info to the Garmin unit using the heading sensor. The heading sensor has 3 wires coming out of it. A red power wire connected to +12v DC, a yellow wire connected to the Channel 2 NEMA plug of the Raytheon MFD and a silver (shield) wire that goes to battery ground and also to a different plug on Channel 2 NEMA on the MFD.

Can I splice (solder) a new wire onto the existing yellow wire coming out of the heading sensor and route that to the free input wire on the Garmin unit and expect the Garmin unit to receive heading info?
Note: I don't want to mess up the heading info to the Raytheon MFD because both the radar and plotter need this info.

OK, let me try a different approach.

Is it possible for my legacy Autohelm heading sensor to supply heading info to 2 chart plotters via NEMA 0183?

Yes...I prefer running old style 0183 to a nice 20 amp (overkill ut it looks neat/clean) Blue seas terminal strip (single strip or double with a jumper). I have had 5-6 different pieces of electronic "listening" to one "talker"...your Autohelm heading sensor.

Thanks psneeld.

When connecting the heading sensor to the Garmin plotter does the negative NEMA need to be connected to the Garmin? The heading sensor is already grounded via it's shield wire to the Raytheon plotter and also to the boat negative battery ground.

And second question: Can my Garmin receive info via it's NEMA 0183 input wire from two different sources. Example: Can I connect the heading sensor and a depth meter output to the same NEMA input on the Garmin.

timjet said:

Thanks psneeld.

When connecting the heading sensor to the Garmin plotter does the negative NEMA need to be connected to the Garmin? The heading sensor is already grounded via it's shield wire to the Raytheon plotter and also to the boat negative battery ground.

And second question: Can my Garmin receive info via it's NEMA 0183 input wire from two different sources. Example: Can I connect the heading sensor and a depth meter output to the same NEMA input on the Garmin.

Click to expand...

I would have to study the suggested wiring as the use of shield vs dc neg gets a bit tricky...at least it did with Garmin years ago.

Not sure about the depth...would have to read up on that one too.

Below is a electronic schematic of my boat with the new Garmin GPS and new VHF radio with AIS.
It looks like I may have to install a multiplexer since both NEMA inputs to the GPS are used with the VHF/AIS.

What I'm trying to achieve is to get all the information on my legacy Raytheon MFD to display on my new Garmin GPS ie: depth, x-track, and heading.

Do you think this is possible?

In NEMA 183 a talker (source) can connect to multiple listeners (receivers). You cannot connect multiple talkers together.

Bob

BobH said:

In NEMA 183 a talker (source) can connect to multiple listeners (receivers). You cannot connect multiple talkers together.

Bob

Click to expand...

Well not directly. But you can if you use a multiplexor. I've just installed an Actisense NDC-4.
Actisense NDC-4. Fully isolated NMEA Data Multiplexer/Combiner > Introduction

I'm feeding Furuno GPS and Sounder (both talkers) into Odyssey Time Zero on a PC (with a nice 24" screen) via a USB port. The Furuno radar and Sounder also listen to the GPS to get lat/long displayed on their screens.

For my flybridge I've added a Simrad NSS 8 MFD (also has built-in GPS), which is about to get an AIS along with a Simrad Autopilot system added via Simnet which is NMEA 2000. I'll feed the NSS 8's NMEA 0183 output (talk) and input (listen) to the Actisense to get AIS data down to the PC, and the Sounder's depth/water temp back up to the NSS. With 2 GPS's in this system, priority is assigned to one or the other in the Actisense setup.

The only thing I wont have on the flybridge is radar display. But the NSS 8 can take a Simrad radar scanner as input (via interface box). At present I'm thinking if I need radar I probably don't want to be up on the flybridge.

Ok, after doing a little research, Bob is correct, NEMA0183 can talk to several sources but will only receive info from one source.
My Garmin plotter is connected to my VHF radio with AIS and the AIS takes up both the NEMA0183 inputs and one output on the Garmin. That leaves only one output available which I will use to connect to my autopilot giving me tracking function.
Since no Garmin inputs are available and I want to connect a heading sensor I would have to get a multiplexer. But how about using a single pole double throw switch to switch between AIS information and heading information.

Like this

AIS
Input
Garmin NEMA input
Heading
Input