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Norman

Linking a VHF to a Chartplotter

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I have a Standard Horizon Quest GX1500E DSC VHF and an Advansea T56 chartplotter. What I want to achieve is sending the GPS position information to the VHF from the Chartplotter and enabling the VHF to send the position of any vessel transmitting a DSC Mayday message to the plotter.

The fun starts because the instructions for NMEA0183 connections for the two devices are not even speaking the same language. The Advansea Plotter has wires in its Power and NMEA cable described as:
Power negative / NMEA ground
NMEA1 out
NMEA1 in
NMEA2 out
NMEA2 in

The VHF has:
NMEA input +
NMEA input -
NMEA output +
NMEA output -

From the above I infer that all of the plotter NMEA wires are positives using a common return. Am I right, and, more importantly which should I connect, as the plotter instructions indicate connecting the NMEA 1 & 2 in wires plus the ground wire to the radio. On the other hand the radio instructions say connect the NMEA input + to the plus output of the GPS, the NMEA input - to the minus output of the GPS and the NMEA output + to the + input of the GPS, but makes no mention of connection to a chartplotter.

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  • What's been holding me back from commenting, is that I am not familiar with the idea of having a shared NMEA ground. Normally there is a "NMEA -" for each individual input and output, just like the VHF has.

    The manual I found is not so helpful and very blurry:
    http://www.advansea.com/manuals/GPS/combo_user_manual_uk.pdf

    I have 3 guesses to the wiring, but I feel pretty strong about the first guess.

    I will make a wild guess, this is what you want to try first. Theory is that this should work with just one NMEA port. After connecting see if your VHF will show lat/long. If this is not the correct wiring, the symptom will be that one of the two functions works and the other does not. If neither function works, look for other issue before advancing to my next two guesses.

    NMEA input + NMEA input - NMEA output + --> Plotter NMEA1 in
    NMEA output - --> Plotter NMEA ground


    I will make a wild guess, this is what you want to try second, if as it seems to indicate, you need 2 NMEA ports.

    NMEA input + NMEA input - NMEA output + --> Plotter NMEA2 in
    NMEA output - --> Plotter NMEA ground

    I will make a wild guess, this is what you want to try third. It is the reverse of the above.

    NMEA input + NMEA input - NMEA output + --> Plotter NMEA1 in
    NMEA output - --> Plotter NMEA ground

    Good Luck

  • Dan, it's very nice of you to work on this issue, but I don't understand the way you've written your solutions. Can you please just explain the first one in terms of actual wires? Are more than two wires involved?

    Incidentally, common ground used to be...um...common for NMEA 0183 and can generally mix with dedicated ground wires OK. I'll explain more later. This stuff is confusing but doesn't really take guess work.

  • Sure Ben, the comment got all jumbled up for some reason (editor doesn't like [left arrow][dash][dash]?) and I didn't realize it.

    Changed it around and put numbers in front of each line, one for each wire.

    1. VHF NMEA input + CONNECT TO Plotter NMEA1 out

    2. VHF NMEA input - CONNECT TO Plotter NMEA ground

    3. VHF NMEA output + CONNECT TO Plotter NMEA1 in

    4. VHF NMEA output - CONNECT TO Plotter NMEA ground (combined with 2 above)

  • Dan, I have connected it, but did so before seeing your reply. I wrote down what I did, but left it on the boat. As far as I remember I connected the VHF Input + to the plotter NMEA 1 out and the VHF NMEA Input - to the 12 volt negative. I also connected the VHF Output + to the plotter, but cannot remember which wire I connected it to though I think it was NMEA 1 in as you indicate above..

    The radio displays position from the plotter, but I don't know if DSC polling will work. I did not connect the VHF output - to anything, so I think I will have to follow your instructions when I return to the boat.

    The Advansea instructions are hopelessly blurred in download form, and the wiring diagrams are particularly unreadable, however the CD instructions are OK.

    Thank you for your help.

  • yeah but wich color is the wires they only give a pin number to identification

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