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© 2009 Active Research Limited
NMEA 0183 Input
The NMEA 0183 differential Opto-isolated input is
designed to handle a variety of NMEA 0183 device output
specifications. The user must determine (from device
manufacturer’s information) if the device(s) required to be
connected to the
Actisense
USG-1 conforms in full to the
NMEA 0183 network communication standard. If it does
not, the flexible
Actisense
USG-1 inputs should still be
capable of interfacing with the device, though this is not
guaranteed.
Figure 2 shows a typical installation with an NMEA Talker
and an NMEA Listener connected to the USG-1.
The NMEA Talker connections may be marked either A/B
or +/- if the talker is a differential drive device, or Tx/GND
for a single-ended device.
NMEA 0183 (ISO-Drive) Output
The NMEA 0183 buffered output is capable of driving up
to 10 NMEA 0183 fully compliant Listening devices, or a
mixture of NMEA 0183 Listening devices and a Personal
Computer (PC) communication port.
However it is only recommended to connect one
listener to the USG-1. If multiple instruments are
connected in parallel to the USG-1, there will be a
chance that isolation will not be maintained between
them, as some of the connected devices may not have
correct opto-isolated inputs.
If the user manuals for the connected instruments indicate
that
all
the listeners are opto-isolated, then they may be
safely parallel connected into the ISO-Drive output, and
safe isolation will be maintained.
The connections on an NMEA Listener may be marked
either
A/B
or
+/-
if the Listener is a differential drive device,
or
Rx/GND
for a single-ended device. Refer to figure 2.
The ground (
GND
) connection must not be connected.
Connecting NMEA 0183 devices
Figure 2 – NMEA 0183 connections
NMEA
Listener
A/+/RX
NMEA
Talker
B/-/GND
A/+/TX
B/-/GND
Do not connect
Notes:
1. To complete the NMEA 0183 standard, all device
interconnection NMEA cables used should meet the
two-conductor, shielded, twisted pair configuration
specification. The shield connection of these wires
should be connected at the instrument end only to
prevent ground loops.
2. Throughout these connection diagrams, the wire
colours represent those actually used on the supplied
Actisense USG-1 data cable. When using the
supplied cable, simply use the colours indicated to
connect to your NMEA 0183 instrument.
3. Refer to the
section for the full details
on input/output specifications.
Summary of Contents for USG-1-B-422
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