Using the Nmea2Wifi multiplexer in a SeaTalkNG environment

Discussion and support for the Nmea2Wifi multiplexer - a 2-input Nmea 0183 wifi multiplexer.
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Luis Sa
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Using the Nmea2Wifi multiplexer in a SeaTalkNG environment

Post by Luis Sa » Mon Sep 25, 2017 10:39 pm

Hello

[Note on 21th November 2018 - the Nmea2Wifi multiplexer is now capable of reading SeaTalk datagrams and coñverting them to Nmea 0183 sentences. Therefore if you have, for example, a ST70 instrument display, you can feed the multiplexer with the SeaTalk data directly from the ST70. In the picture below there is a "disconnected" SeaTalk cable that once was connected to a E85001 Raymarine conversion box]

Before installing Nmea2Wifi in our Oceanis 40, the Raymarine electronic setup was like depicted here. This setup is based on the SeaTalkNG bus (very similar to Nmea2000). Therefore there was a need to a Nmea2000 to Nmea0183 converter. Our boat came with a Raymarine PC/SeaTalk/Nmea Interface box (part E85001). This box, which has been retired by Raymarine, makes the conversion between SeaTalk (not SeaTalkNG) and Nmea0183. So there is the need to convert between SeaTalkNG to SeaTalk. This conversion is made by the ST70 instrument that is on the right side on the previous diagram. Instead of using this 2 step process to convert SeaTalkNG to Nmea0183, I used the bridge function provided by the C90W chartplotter. This unit has 3 Nmea0183 input ports and 2 Nmea0183 output ports as shown here.

c90w-nmea.jpg

Therefore I disconnected the E85001 interface box and used one of the C90W Nmea0183 outputs to get the Nmea0183 data into the multiplexer. As the C90W is in the cockpit and the multiplexer and the VHF radio are in the saloon, I used the same C90W output to feed both the multiplexer and the radio in order to save for an extra cable.

Raymarine_Oceanis_40w.jpg


My AIS receiver is Nasa Marine Engine 3. I tried to connect the output of the Nasa AIS (pin 2 of the DB9 socket) to both the Multiplexer and the corresponding Nmea0183 input of the chartplotter. But I found that the Nasa AIS had not the capability to drive the 2 systems simultaneously. This was strange to me as the multiplexer needs very little drive current (input impedance of 2K2 ohms plus a diode). So the AIS only feeds the multiplexer (A2 B2) and the multiplexer repeats the AIS on its output (A3 B3) which is connected to the C90W chartplotter.


Regards, Luis

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