NMEA 2000


NMEA 2000 is a networking standard for marine electronics, used by most modern marine electronics hardware. It is is constructed from a a number of devices connected to a single bus, called the network backbone. All devices on the network can both transmit and receive messages.

An illustration of a typical NMEA 2000 network with some example devices is shown below.

Example NMEA 2000 Network.

Figure components are:

N2K power cable. Every NMEA 2000 network segment must be connected to boat's 12 V power system. Ideally, the power connection should be roughly in the middle of the backbone.
Network male and female terminators. The network backbone must be terminated with 120 ohm resistors for proper network operation. The are mandatory and essential!
Drop cables are connected to the backbone using T-connectors. The T-connectiors can have one or multiple drop cable connections.
Backbone cables extend the backbone. The maximum length of the network, measured from terminator to terminator, should not exceed 100 m.
Drop cables connect individual devices to the backbone. The maximum length of the drop cable is 6 m.
A display device such as a Multi-function Display (MFD).
A wind sensor.
A temperature sensor.
An SH-wg device.

The network backbone is shown in pale blue color. All devices connect to the backbone using drop cables. Only one device can be connected to a single drop cable.

At the very minimum, the network must have a 5-way T-connector, two terminators, a power connection, and two devices with their own drop cables.