This is the main communication path of the NMEA 2000^® network. The backbone can be as simple as three T-connectors connected side to side with terminators on both ends, or can expand to include many T-connectors separated by backbone cables. The backbone must always be constructed in a linear manner for the network to function properly (Linear Backbone Construction).

Backbone cables extend the NMEA 2000 backbone to connect NMEA 2000 devices located in different places on the boat. The maximum length of a single backbone cable is 100 m (328 ft.). Backbone cables must connect to the sides of two T-connectors to maintain linear backbone construction, and must never connect to the top of a T-connector (Linear Backbone Construction).

Electronic hardware that connects to the NMEA 2000 network. A device may only transmit data to the network, receive data transmitted by other devices on the network, or may both transmit and receive data on the network.

A cable connecting an NMEA 2000 device to the NMEA 2000 backbone. Drop cables are limited to 6 m (20 ft.) maximum length. Drop cables must connect to the top of a T-connector or to the side of an in-line terminator (Linear Backbone Construction).

A special terminator that can be used in place of a male terminator (not available as a female connector), that allows direct connection to the a device at the end of the NMEA 2000 backbone. The inline terminator simplifies installation by not requiring a T-connector, male terminator, and drop cable for the device at the end of the backbone (Network Termination).

A simplified value that represents the amount of current a device draws from the NMEA 2000 network. A LEN of 1 = 50 mA. Each device should have an LEN specified on the product or in the product documentation that you should use when calculating the power needs and balance of your NMEA 2000 network (Power Distribution and Balance).

12 Vdc power supplied to the NMEA 2000 network. Power to the NMEA 2000 network should be connected through a switch (instead of directly connected to the battery) because some NMEA 2000 devices are always on when power is present, and this may drain the battery. NMEA 2000 devices must operate from 9 to 16 Vdc, with a nominal voltage of 12 Vdc (Linear Backbone Construction).

A 120 ohm resistor located at each end of the NMEA 2000 backbone. Proper termination is required to ensure signal integrity across the entire length of the backbone (Linear Backbone Construction).

A three-way connector with one male and two female micro connectors. A T-connector is used to connect an NMEA 2000 device to the NMEA 2000 backbone.