"Jack Erbes" wrote in message
...
Sounds like you're using the right connections then. NMEA is RS-232 by
definition.

Wrong. NMEA is RS-422 by definition. And if everyone would have adhered to
that standard, we wouldn't have so many problems with intermixing RS-422 and
RS-232 devices. Every NMEA device should have an output labeled Out A and
Out B and an input named In A and In B. NMEA standard, chapter 3. But it was
the manufacturers who made a mess of it.
Take a look at www.shipmodul.com/en/connections.html for primer on NMEA
connections.

Meindert