What if my NMEA Listener does not have an isolated input or uses ground for the negative data connection?
The NMEA 0183 specification, from version 2 (1996) onwards, requires a device’s Listener port to be isolated. Some NMEA 0183 devices however choose instead to follow version 1 of the specification which allowed for non-isolated inputs to be used.
The NBF-3 Talker/Output ports are all isolated so that an NMEA Listener (or other device) without an isolated input can be safely connected with no fear of ground-loop damage. Isolation is between every NBF-3 connection; power, Listener/Input port and all Talker/Output ports.