Originally Posted by Yobbo
Hi, thanks for your reply, so to use NMEA port one on my Garmin, I wire AIS pin 6 - Garmin wire 2 Black and AIS pin 7 - Garmin wire 4 Brown?
would that be correct to view AIS data on the Garmin?
Partly, maybe. How's that for a non-answer?
Normally you need to wire the two Tx wires from the AIS to the two Rx wires on the Garmin. And when doing it, you connect plus and plus together (sometimes called A rather than plus), and connect minus and minus together (sometimes called B rather than minus).
But this raises an issue that I didn't notice earlier. This is one of the Garmins that doesn't implement proper 0183/RS-422, and doesn't have true differential signals. Hence only a single Tx and Rx for each port. Shame on them. Some old VHFs are like this too. You are going to have to find the Garmin manual and see how they say to wire it up.