Help connecting GPS to DSC VHF

[DiggersC5]

Good evening

I've struggled with this (simple) wiring problem for too long

I have a Garmin 178C Chartplotter / Finder and a West Marine VHF 600 fixed radio. Both are a couple of years old, but should work together.

The wires to the two harnesses don't have the same names or colors.
I'm including scans from each manual and am hoping that somebody can tell me which wire should connect to which wire. I think I've tried every configuration except the right one and keep receiving a "check wiring" error message on the GPS.

Here's a link to scans of the wiring harnesses.

Your help would be appreciated

 

[jhebert]

Re: Help connecting GPS to DSC VHF

Connect the NMEA Data (+) OUTPUT from the GPS receiver to the NMEA DATA (+) input of the radio.

If the Radio NMEA DATA has a (-) input, connect it to the power ground of the GPS receiver.

 

[DiggersC5]

Re: Help connecting GPS to DSC VHF

Thanks for the note.
I had considered that as the GPS doesn't have available negative leads that are available to match the negative leads from the radio wiring harness.


I'll give it a try and let you know what happens.
I appreciate your help.

Doug

 

[jhebert]

Re: Help connecting GPS to DSC VHF

Thanks for the note.
I had considered that as the GPS doesn't have available negative leads that are available to match the negative leads from the radio wiring harness.

The use of the "+" and "-" notation regarding serial data NMEA signals does not refer to polarity, that is, they are not "plus" and "minus" as you would think of a voltage.

The "+" indicates the non-inverting input; the "-" indicates the inverting input.

The GPS is the data signal source, and the data signal is not a differential signal. There is only a single wire on which the data signal is available, and it's signaled with respect to the power ground.

The radio is a listener or receiver of the data signal. It has a differential data input, with non-inverting and inverting inputs. You connect the inverting input (noted by the "-") to the power ground.

 

[DiggersC5]

Re: Help connecting GPS to DSC VHF

It worked!
Thank you very much for your help!
1 nagging item off my list, and another 20 to go.
Have a great day.