This multiplexer acts like a bridge allowing the connection between Nmea 0183 and Nmea2000 (referred to here as N2K) devices. You can combine Nmea0183 sensors and have them transmitting data on a N2K system. In the other direction you can connect this multiplexer to the N2K bus and set it to convert the data on the bus to Nmea0183 sentences for applications that do not support the N2K standard. Using WiFi or wired connections, you can transform your smartphone or laptop computer in a powerful chart plotter. On the Nmea0183 side, the system has 2 opto-isolated Nmea 0183 input ports and one Nmea 0183 output port as well as an input/output USB port. It also has a bidirectional N2K connection that can work as an input or as an output. Data messages received from the N2K bus can be converted to Nmea 0183 sentences and Nmea0183 data can be converted to N2K messages and sent on the N2K bus. WiFi communication supports both the UDP and the TCP internet protocols. In total there can exist 6 input streams of data (2 serial, 2 WiFi, 1 N2K and 1 from an EXTernal paired multiplexer) and 5 output streams of data (1 serial, 2 WiFi, 1 N2K and 1 to an EXTernal paired multiplexer). The 6 input streams can be filtered, combined and routed to any of the 5 outputs streams. Filtering is possible on the Nmea0183 sentences and on the N2K bus messages. The multiplexer can also be used as debugger or analyser of the data that travels on the N2K bus.


Microcontroller: ESP32 (2 cores – 4MB – 240 MHz)
Power Supply Voltage: powered from the N2K bus or from a 7V up to 16V DC power supply
Power Consumption:
   less than 90mA with Wifi ON
   less than 10mA with Wifi OFF and Serial OFF
Nmea 183 Input Ports: P1 and PX - optically isolated (PX is available internally)
Nmea 183 Output Port: P2 - RS-422 compatible
N2K Port: input and output (fully bidirectional)
Baud Rates:
   P1 and PX = 4800, 9600, 19200 or 38400
   P2 and USB = 4800 , 9600, 19200, 38400, 57600 or 115200
Nmea 0183 Sentence Filtering: serial inputs and output, N2K output and WiFi inputs
N2K Message Filtering: on the incoming N2K input
Firmware Update: Over The Air (OTA) without cables
WiFi protocols: UDP and TCP
Other: operation in Simulation mode or Debug mode


Before installation and to get acquainted with the multiplexer, you can power it from a computer solely with an USB cable. You can get access to the WiFi network described below, choose Simulation Mode and try to receive simulated instrument and AIS data in applications like Navionics , OpenCPN or others. You can power the unit from the N2K bus or from a 12V power supply if you are not using the N2K capabilities (consider to use a fuse or a circuit braker if you are connecting the multiplexer directly from a battery). If you are using the N2K bus you connect its 4 wires: 12V (normally red), GND (normally black) CAN-LOW (normally blue) and CAN-HIGH (normally white) to the screw connectors with the referred to labels. In the case that you are not using the N2K bus, you only use 12V and GND and leave the other 2 terminals unconnected. The  serial input and output ports, P1 and P2, have labels A1/B1 and A2/B2. Some instruments instead of A/B use Nmea+/Nmea- . In such a case you connect Nmea+ to A1 (or to A2) and Nmea- to B1 (or B2). If your Nmea data is available through a single ended port (such as RS-232) you connect its Output terminal to the multiplexer A1 and its Ground (or common) terminal to the multiplexer B1. The serial output port P2 uses the connectors labelled as A2 and B2. There is an extra serial input port but its 2 terminals are not available externally. In order to use this input port, you need to open the plastic box of the multiplexer and take 2 wires from the pins labelled as AX and BX available at the H2 6 pin SIL header. There are two 6 pin SIL headers, H1 and H2, where several pins from the ESP32 microcontroller are available for advanced users that want to use the multiplexer as a development tool, together with GND, +5V and +3.3V voltages used in the circuit. If you connect the P2 output port to a non opto isolated Nmea0183 input port, there is a possibility of creating undesirable ground loops. This problem (and solutions) is covered in this webpage.


This multiplexer is totally WiFi configurable. When powered for the first time, it starts with factory settings and it will automatically create a WiFi network named N2K0183. You should disconnect your smartphone (or your PC) from other networks (if possible turning mobile data OFF) and connect to this N2K0183 network using the password 12345678. When you are connected, type the address in the navigation bar of your browser and you will receive a web page which allows you to fully configure the multiplexer, and select all the modes of operation.


At any time, you can return to default factory settings by pressing and holding down the small micro switch labelled HARD or SW2. The Leds will go ON and will go OFF again 2 seconds later, after which you may release the switch. For more support please visit the forum dedicated to the N2K0183 multiplexer. Note that updated versions may exist in the future, which can differ from the pictures shown in this page.


This web page is the response you receive when you type in the navigation bar of your browser after you connect to the network created by the N2K0183 multiplexer. Note that the page will not respond to the commands SET, HARD RESET and UPDATE as it is not running in the multiplexer. Please see the sections in this site that describe these functions.


In contrast to the other multiplexers, the N2K0183 multiplexer is only available as a SMD version. It could be the case that you need to open the box in order to bring outside wire connections to use the internal input PX port. The box is opened with 4 screws. You should take care not to loose the 4 small o-rings that will go between the PCB and the base of the box. The picture below shows the referred to o-rings.