“Everybody thinks they can avoid getting a multiplexer, and in the end they always get multiplexers.”
—Brad Christian, Rose Point Navigation
Yeah, sure, whatever, Brad.
Longtime Navagear readers are aware that I have been avoiding multiplexers for more than three years (here’s the proof). I’ve had a good deal of success.
And also a good deal of…um…unsuccess. 
Today I enjoyed a big success, though, completing and testing the installation of a new NoLand AM43 NMEA 0183 multiplexer. So it turns out Brad is right. Again. I’m getting kinda tired of that, Brad! 
The guys at NoLand have been very helpful, answering over email some questions I had. The diagram above shows a typical installation, but mine was slightly different. I’ll share my schematic diagram here. The top is some general brainstorming. The bottom shows what’s actually connected to each terminal.
A careful look might reveal something odd: Why does the TLK/com pair connect right back to the unit through the IN1+/IN1-? If the data is already in the multiplexer, why feed it back?
Turns out the TLK port is the only “talker” carrying data received from the PC. I want that datastream aggregated into the primary OUTh port; that’s the one that goes to my Raymarine C-80 chartplotter.
And it works! If I select a waypoint in Rose Point Coastal Explorer and make it “active”, my C-80 asks if I want to engage the autopilot to navigate to that waypoint.
And for the first time, I’ve got AIS targets displaying on both the PC and the C-80. Oh, and I verified that DSC targets sent from the VHF appear on the C-80. I haven’t verified that they appear on the PC, but I expect they will.
It’s only day one, but so far I’m impressed that the NoLand AM43 does what it says it will.
If I had any suggestions for future products, it would be to include one more high-speed input. So there would be 2 high-speed inputs and 1 high-speed output. Why? In addition to the AIS, I want to plug the NMEA output from the C-80 into the multiplexer, to get all the data from the C-80 (autopilot, GPS, depth, speed, etc.) into the PC. That data doesn’t actually require a high-speed pipe, but on my C-80, I have to set a common data speed for both the input and output ports. I can’t set the input to 38,400 baud and the output to 4800 baud.
So right now, I’m still obliged to use a clunky workaround, pulling what data is available from the 4800-baud NMEA-out in my autopilot. That set of data is somewhat incomplete, and it’s a shame, especially since the NMEA out on the C-80 (configured at 38,400 baud so that the input can accept the AIS datastream) isn’t connected to anything right now! I guess I could run it into the PC through an unused USB port, but it seems a shame to run an extra wire for it.
Next time I actually take the boat out of her slip, I’ll put the whole kit and caboodle to the test. Stay tuned!
{ 3 comments… read them below or add one }
Hey Tim,
I am in the same boat (well same chartplotter) as you and would like to do some crazy configuration with multiple inputs and output and have been hurting my head to figure out how to make it work.
I assume your rate sensor is incorporated into the autopilot? I need MARPA to work correctly and won’t have an autopilot at this point, so I will have an external heading sensor, have been thinking about the Airmar H2183 (Garmin unit).
So basically you can’t receive any data out of the C80 then to other devices?
Could you have used one of the Noland DX28′s to expand the input/output lines?
Thanks,
Chris Hallock
Chris, I think I’m going to be out of my depth pretty quickly here. Let me pass your message along to the guys at NoLand.
Tim:
This is interesting. I wonder: can you create a route on the PC and then “transfer” it to the C80with this multiplexer? I find that route creation on the C80 is tedious, but a joy on the PC (GPSnavX on a mac). Up till now, I haven’t been able to transfer between the two because I fell for the Raymarine multiplexer, which doesn’t do that trick. I’m in the market for a new mux.
Thanks,
Lloyd Bray
s/v “PALIO”
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