Lowrance electronic LMF-400 guide

For complete instructions on setting up a new NMEA 2000 network or expanding an existing one, see the other document packed with your gauge, "Setup and Installation of NMEA 2000 Networks, General Information" part number 988-0154-172. If that document is missing, it can be downloaded free from the Lowrance web site.

Network Nodes

A network bus is built of network nodes spread along a backbone. Network nodes are made by fitting T-shaped connectors into the backbone (using the sockets on the sides), and attaching a display unit or sensor at the bottom of the "T."

Using our telephone example, the T connectors are similar to telephone jacks. The backbone is like the phone wiring running through a house. Phones in a house must be connected to each other to communicate, and in the same way only sensors and display units plugged into the NMEA network can share information.

Connections found in the middle of the bus will have one or more of these T-shaped connectors with the backbone cables plugged into both sides. Connections at the end of a network will have the backbone plugged into one side, and a terminator plugged into the other, as shown in the following figure.

Cable from		LEI or Lowrance
Cable from		device needs an
sensor or		device needs an
sensor or		open T.
display unit		open T.
display unit
T connector		Terminator at
		Terminator at
		the very end
		of the bus

Backbone cable (to rest of bus)

NMEA 2000 network node located at the end of a NMEA 2000 bus.

Adding a Network Node

You can add a node anywhere along the network backbone where a connection already exists. This connection could be at the end of the network (between a T connector and a terminator), between two T connectors, between a T connector and a backbone extension cable, or between two extension cables. Wherever you want to add the new node, simply separate the sockets of the old connection and attach your new T connector between them.