Specifications
Actisense
®
Page 10© 2011 Active Research Limited
Single-ended NMEA talker
These are the recommended methods of connection for a
single-ended, pre - NMEA version 2.0 talker.
Many instruments that output version 2.0 formatted strings
use a single-ended output. This is often the case with
some of the hand-held GPS units such as from Garmin,
as the circuitry to produce the differential output is more
complex, and requires extra connector pins.
Single ended outputs are normally labelled ‘NMEA Tx’,
‘NMEA Out’ or just ‘Data’. The ground connection is used
as the data signal reference.
Case (1): Standard differential NMEA 0183
v2.0+ device
This device is a differential device conforming in full to the
NMEA 0183 v2.0 (or higher) standard.
Its “NMEA +/A” input is connected to the “NMEA Tx”
output of the single ended device. It’s “NMEA -/B” input
is connected to the “Ground” of the single ended device.
This connection is required to provide data signal return
current path for the opto-isolated NMEA listener. If the
NMEA “-/B” input is left oating, then data corruption /
errors may occur, or more likely, no data will be seen.
Case (2): Single ended NMEA interface
devices
This device is a single ended listener. This listener is
simply connected as “NMEA Out / Data or Tx” to “(NMEA)
In / Rx” and “Ground” to “Ground” of the single ended
device
NMEA
Listener
NMEA 0183 ‘Single-Ended’ Talker connected
to NMEA ‘OPTO-Isolated’ Listener
+
-
A/
B/
NMEA Tx
Ground
NMEA 0183 Single
ended talker
NMEA
Listener
NMEA 0183 ‘Single-Ended’ Talker connected
to NMEA 0183 ‘Single Ended’ Listener
Rx
GND
NMEA Tx
Ground
NMEA 0183 Single
ended talker