HOW TO CONNECT A NMEA0183 TALKER TO A NMEAXWIFI MULTIPLEXER

The connections between NMEA 0183 output devices, also referred to as talkers, and the inputs of Vela-Navega multiplexers are shown in the following picture. If the data is provided through a differential output, connect the talker’s A (or NMEA+) terminal to the multiplexer’s A input and its B (or NMEA−) terminal to the multiplexer’s B input. If the data is provided through a single-ended output, such as RS-232, connect the talker’s Output terminal to the multiplexer’s A input and its Ground or Common terminal to the multiplexer’s B input.

HOW TO CONNECT A NMEAXWIFI MULTIPLEXER TO A NMEA0183 LISTENER 

Older multiplexers have a three-pin output connector labelled A, B and GND. More recent units have a two-pin connector labelled A and B, together with a jumper having positions 1 and 2.

When connecting an older multiplexer to an optically isolated differential listener, connect A to the listener’s A (or NMEA+) terminal and B to its B (or NMEA−) terminal. When connecting it to a non-isolated single-ended listener, connect A to the listener’s Input terminal, leave B unconnected, and connect the GND terminals of the multiplexer and listener together.

Do not connect the B output of a non-isolated multiplexer directly to the Ground of a listener, as this may short-circuit and damage the output driver. To avoid this possibility, recent multiplexers use a two-pin A/B connector and a configuration jumper. In position 1, which is the default, B is connected to GND and the port operates as a single-ended output. In position 2, B is connected to the negative output of the driver and the port operates as a differential output.

The P2 output of the N2K0183 multiplexer has only two terminals, A2 and B2, and does not have a configuration jumper. It should therefore be connected only to an optically isolated listener. Alternatively, a non-isolated single-ended listener can be converted into an isolated listener using the adapters described here. 

 NME3PRO GALVANICALLY ISOLATED OUTPUT

The Nme3Pro P4 output is galvanically isolated from the multiplexer’s internal circuitry and Ground. It can therefore be connected safely to either a differential or a single-ended NMEA 0183 listener, without the ground-loop and output-driver risks described above.

For a differential listener, connect A4 to its A (or NMEA+) terminal and B4 to its B (or NMEA−) terminal. For a single-ended listener, connect A4 to its Input terminal and B4 to its Ground or Common terminal. No connection to the multiplexer’s GND terminal is required.