OpenCPN is one of the most popular marine navigation software packages and is completely Open Source, meaning that Windows, Mac and LINUX users can install and use the software for free!

This section explains how to receive NMEA data in OpenCPN V3.2 or higher from an NMEA to USB adaptor or from a sensor with USB output like our GPS antenna.

If you want to receive NMEA data from WiFi (with an NMEA to WiFi server), please click here.


1 – Discover the device name

First of all, make sure that the relevant USB driver for your Digital Yacht product, is installed on the computer.

During the “Discovery” process, the operating system will allocate a device name to the USB connection. On Windows PCs these are always “Virtual COM Ports” and will be numbered COM1 through to COM256, while on MACs and LINUX PCs these will be device names “tty.usb1”. Before you can setup OpenCPN, you need to know what device name has been allocated to your Digital Yacht Product and this varies between operating systems:

For Windows PC, to find out what COM Port number has been allocated, you will need to run the “Device Manager”. The Digital Yacht unit will be displayed as “USB Serial Port (COMxx)” and it is the number (in this example 6) that we are interested in.

Device manager Windows

For Macs, in Finder, click GO>Utilities and run the program. Then type “ls /dev/tty.usb*” which will then display the device name given to the Digital Yacht product, in this example “/dev/tty.usbmodem1d11” is our AIT2000 and “/dev/tty.usbserial-FTTQLRK4” is one of our NMEA to USB adaptor cables. Make a note of the device name(s) as we will need to enter this in OpenCPN.

For LINUX PCs, the exact command you use will depend upon which LINUX distribution you are using but for Ubuntu, click “Applications>Accessories>Terminal”. At the command prompt, enter the command;

ls /dev/ttyA* for AIT1500/AIT2000/AIT3000 and other AIS transponders products
ls /dev/ttyU* for all other products such as NMEA to USB adaptor, GPS with USB output, etc.

This will display the device name given to the Digital Yacht product. In this example below we have an AIT2000 connected that is given the device name “/dev/ttyACM0” and a GPS160USB that was given “dev/ttyUSB0”. Make a note of the device name(s) as we will need to enter this in OpenCPN


2 – Set up a NMEA connection in OpenCPN

With the latest V3.2 and higher versions of OpenCPN you can have multiple data connections and to create a new connection you must click on the “Settings” icon (spanner) and then click on the “Connections” tab. As you can see, we currently have no Data Connections setup and so we click on the “Add Connection” button. Now we click on Serial then on the “DataPort“ drop down list and see what serial ports are available. Find the device name that matches the name noted earlier for your Digital Yacht product and select that device.

OpenCPN NMEA settings

The default baud rate (data speed) is 4800baud which is the standard speed for most NMEA0183 devices, but if you are connecting one of our AIS products, you will need to change the Baudrate to 38400 baud.

None of the other settings usually need to be changed and once you are happy that everything is correct, click on the “Apply” button to save the settings and you will see the new connection now in the list. If you wish to test the connection, click on the “Show NMEA Debug Window” tick box and a new window will appear with the raw NMEA data scrolling down the page, showing the time it was received and the connection it came in on.

show debug nmea in opencpn

You can continue to add more data connections i.e. GPS, AIS, Instruments, etc. and once all connections are setup just click “OK” to exit and return to the Chart screen. Assuming that all of the connections are powered up and active, you should now see the Boat displayed accurately on the chart, if an AIS is connected then a series of AIS targets should be displayed on the chart and if you have the Dashboard Instrument Plugin installed, you should be able to display instrument data as well.


Important Notes
1) We have had some reports of customers having to go in to the Input Filtering “Accept Only” options and clicking the “Select All” Sentences button. There does not seem to be any rhyme or reason for this and we recommend only changing the Input Filtering if no data is being displayed and you are sure everything else is set and working correctly.

2) For Mac and LINUX users, if when you click on the drop down “DataPort” menu you do not see the device name that you had found previously in the Terminal program, you will need to manually type the name in to the box. We have seen this on some Macs and LINUX distributions with our AIT1500/AIT2000/AIT3000 products that appear as a USB Modem rather than a USB Serial Port. Make sure you include the full device name for example; /dev/tty.usbmodem1d11


3 – Configure AIS parameters

If you have connected the USB output of an AIS transponder/Receiver or if your AIS is connected to an NMEA to USB adaptor, then you can overlay AIS targets in OpenCPN after having configured the USB connection.

You need to make sure that AIS targets are activated. Go to the top menu bar > AIS and tick the parameters you want.

AIS settings in OpenCPN

You can also configure others AIS parameters such as CPA/TCPA alarms and the display of AIS targets in the OpenCPN menu. By configuring CPA/TCPA alarms, your PC can trigger an audible alarm.

If you want to configure those parameters, go to OpenCPN settings > Ships > ‘AIS Targets’ tab.

AIS settings in OpenCPN

AIS targets will now be overlay in your charts.

AIS targets in OpenCPN