AM43 – NMEA 0183 Hi-speed Multiplexer

AM43 – NMEA 0183 Hi-speed Multiplexer

The AM43 Multiplexer combines up to four NMEA 0183 inputs into common outputs. It supports AIS inputs with baud rates to 38,400 as well as encapsulation sentences. Multiple outputs are provided: a USB interface and two NMEA 0183 outputs (4800 – 38,400 baud). A “Talker” (TLK) port is also included to allow a computer to request specific messages from instruments or to send data such as waypoints, routes, or steering commands.


The AM43 multiplexer performs serial data multiplexing by combining up to 4 NMEA 0183 data inputs into two NMEA 0183 outputs. Three of the inputs are for traditional NMEA 0183 lo-speed data(4800/9600 baud). The fourth input supports AIS and other hi-speed inputs up to 38,400 baud.

Two NMEA 0183 outputs are provided. The lo-speed output has the combined data from the three lo-speed inputs, while the hi-speed output contains the combined data from all four inputs. The lo-speed and hi-speed outputs normally runs at 4800 and 38,400 baud respectively, but these can be changed, if necessary.

The AM43 also has a USB interface, which allows a PC and its navigation software to access the NMEA data. All hi-speed output data is automatically sent to the PC via USB. The PC software can then send NMEA data to the AM43 (via USB), which appears at the "TLK" ouput connection of the AM43. This “Talker” data may be sent to instruments such as a GPS and/or Autopilot to use. The USB interface is also used for data motoring and troubleshooting, as well as configuration changes, such as baud rate.

A multicolor LED shows operating status of the multiplexer. Green indicates an input is receiving valid data. Red indicates the PC is sending data. Yellow indicates an error has occurred. Error messages are sent to the USB output to aid in fault detection.


Supply Voltage/Current: 8-30 Vdc, 100 mA. max
Input drive voltage: 2-14 V (active state)
Input Impedance(INh): 500 ohms
OUT, TLK level: 4V
OUT, TLK baud rate: 4800 (fixed)
OUTh+ / OUTh- level: 4V differential (RS-422)
INh / OUTh baud rate: 4800 – 38400 (selectable)
IN1 baud rate: 4800 or 9600 (selectable)
IN2, IN3 baud rate: 4800 (fixed)
Operating Temp (℃): -20 – 70 °C
Humidity range: 0 – 100% (non-condensing)
Size/weight: 3.88″ x 2.4″ x 0.9″ / 6 oz.
Warranty: 3 year repair/replacement


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