Raymarine NMEA Multiplexer - Manual (Page 11)

5
NMEA out
Connect the a and b terminals of the NMEA Out connector to
the listening ports of up to four devices to which you wish to
transmit multiplexed data. The manner in which the connections
NMEA out -
NMEA Multiplexer
NMEA out +
Device with
single-ended NMEA output
Ground
NMEA Multiplexer
Note: NMEA outputs from Raymarine products are differential.
Shield
D7587-1
NMEA In a
NMEA In b
Device with
differential NMEA output
& shield connection
Cable
shield
NMEA out -
NMEA Multiplexer
NMEA In a
NMEA In b
Shld
Device with
differential NMEA output
but no shield connection
NMEA out +
NMEA out +
Cable
shield
Cable
shield
NMEA In a
NMEA In b