Lowrance NMEA 2000 User Manual

™

Pub. 988-0154-173

Setup and Installation of

NMEA 2000® Networks

General Information

The NMEA 2000 Network DeviceNet is the communication bus stan­dard developed by the National Marine Electronics Association
(NMEA) for use in boats. Lowrance has introduced a line of products
that can communicate over a NMEA 2000 network, helping you get the
most out of this technology.

This instruction sheet will show how a NMEA 2000 network is created,
configured and installed.

Read the next few pages to become familiar with some of the following
terms: NMEA 2000 Network/LowranceNET, NMEA 2000 Bus/Network
Bus, Network Backbone, Network Nodes and Linear Architecture.

NMEA 2000® Network or LowranceNET™

A NMEA 2000 network is a communications link between two or more
devices that transfer NMEA 2000 information. LowranceNET is the
NMEA 2000 networking system developed by Lowrance Electronics. A
NMEA 2000 network functions like the phone wiring in a house. If, for
example, you pick up a phone in the living room you will be able to
hear the conversation someone is having on a phone in the bedroom.

In similar fashion, a NMEA 2000 network allows multiple display units
to receive data from a GPS antenna or multiple sonar units to receive
messages sent by a temperature sensor. A NMEA 2000 network gives
you the flexibility to view engine diagnostics and fuel level data on digi­tal gauges or display units located anywhere on your boat.

If you have a Lowrance display unit with a LGC-3000 GPS module in­stalled, you have a NMEA 2000 network. The connectors and cables
that came with your LGC-3000 function as a dedicated NMEA 2000
network, passing GPS data along the network to the GPS display unit.
This is a simple form of a NMEA 2000 network.

On the other end of the scale is a large network bus. You can easily ex­pand a network bus by adding multiple NMEA 2000 devices, even add­ing the same type of device more than once.

The network could share information with a sonar-GPS combo unit
mounted in the dash, a sonar-only unit mounted at the stern and an­other display unit mounted on the bow. In that scenario, all three dis-

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play units attached to the bus would have access to information from
every sensor attached to the network. That is the advantage of a NMEA
2000 network.

WARNING:

The network MUST be installed in an area where it
WILL NOT be submerged in standing water during nor­mal operation of your vessel.

NOTE:

We recommend applying dielectric grease to all NMEA 2000 back­bone and device connections. This will prevent moisture from cor­roding the connector terminals. Before connecting a T connector to
another T connector or a NMEA 2000 device, apply a small amount
of dielectric grease on the pin connectors of both male and female
connectors.

Every display unit, gauge or sensor attached to the network can commu­nicate with all other devices on the network. Location, speed and tempera­ture, however, are not the only kinds of information that can be shared.
Fuel Remaining data along with engine information like oil pressure and
fuel efficiency are among a large number of data options that may be
shared on the network.

NOTE:

Full Sonar Chart returns CANNOT be transmitted on a NMEA 2000
network, because they take too much bandwidth for the network.
Every sonar display unit requires its own transducer. If, however,
you have a sonar display unit (with sonar bottom lock) connected to
the NMEA bus, it will share the digital depth with all display units
on the network.

NMEA 2000 Bus or Network Bus

Technically, any physical cable used to transfer network information is
a network bus, but in our documentation we use this term to refer to
the standard manufacturer installation appearing in new boats. This
network bus is an operational network cable, connected to a power sup­ply and properly terminated, that will run the length of your boat. It
will provide access to network nodes at various locations on the boat.

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(

)

Connection for backbone

Sides of T

(Connection for devices)

Bottom of T

This T connector allows you to add a device to your NMEA 2000 bus

creating a network node.

Network Backbone and Network Nodes

A network bus backbone consists of network cabling, terminators and T
connectors. Network nodes are made by fitting T-shaped connectors into
the backbone (using the sockets on the sides) and attaching any network
device to the bottom of the T.

Double T connector

Staying with the previous phone wiring example, T connectors on the
backbone are the equivalent of phone jacks spread throughout a house.
To pick up a phone and be able to hear a conversation from another
phone in the house, both phones have to be connected to the main phone
line. In similar fashion, only sensors and display units plugged into the
NMEA network can share information. The network backbone is like the
phone wiring that runs throughout a home.

It connects the network nodes, allowing them to communicate across the
network. Connections found in the middle of the bus could have T connec­tors or backbone network cable plugged into one or both sides. Connec-

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tions at the end of a network will have the backbone cable plugged into
one side and a terminator plugged into the other, as shown in the follow­ing figure.

Backbone cable
Terminator at
the end of the
backbone (bus)

Cap for unused
connector

Double T
connector

(to rest of bus)

Cable from
sensor or
display unit

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

NOTE:

If you have a double T Connector on your network that is not at­tached to a device, you must cap the unused connector with a
NMEA 2000 cap. This will protect the pin connectors from corro­sion. The NMEA 2000 cap looks like a terminator, but has "Cap"
stamped into the connector housing.

All T connectors on your network probably will be connected to a device.
If you want to add another node to a working network, add another T
connector. T connectors may be purchased from LEI (ordering informa­tion appears on the back page of this booklet). If you are adding a
Lowrance or LEI NMEA 2000 sensor, it will come with its own T connec­tor.

Linear Architecture

NMEA 2000 networks are constructed using a linear pattern. It is impor­tant linear architecture is maintained when the network is modified or a
node is added to the network.

Linear architecture refers to way the network's nodes are connected to
the network backbone. Note that every T connector has two female sock­ets and one male socket. This means you could connect it in two differ­ent ways. Using linear construction, the T connectors will be connected
side by side, leaving the bottom of the T available for connection to a
display unit or NMEA 2000 device, like the "Correct installation" figure
on the next page. A network built following a linear construction is eas­ier to maintain and expand.

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It also allows you to ensure the two terminators are at the ends of the

p

r

backbone. If your installation does not follow a linear architecture, the
network may not function.

Backbone (Network bus)

This network bus has a cluster of single and double T connectors and is

terminated on both ends. It is connected to a display unit and four NMEA

2000 devices.

You could use the recommended installation, plugging the sensor or
display unit into the bottom of the T and the backbone cable into the
side of the T. You also could plug the sensor or display unit into the
side of the T and the backbone connection into the bottom of the T. The
sockets would allow you to make that connection, but you would lose
linear construction. Both installations are detailed in the following fig­ures.

Correct installation

Sonar or GPS
display unit

EP-35
tem

LGC­3000

senso

Incorrect installation

Sonar or GPS
display unit

EP-35
temp sensor

LGC­3000

Two possible network designs. The design on the left maintains a linear

architecture while the one on the right does not. You should always

maintain linear architecture when building a NMEA 2000 network.

Both network designs in these images contain the same set of compo­nents. Both networks are terminated and all of the connectors are able

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to be connected to one another, but the installation on the left comes to
a clear end with terminators on each end of the backbone. The non­linear installation on the right has no clear end, increasing the chance
of an installation error.

It also makes network expansion more difficult and could even prevent
the network from functioning.

Always maintain linear architecture when modifying your network.
Make sure display units or sensors are attached to the bottom of the T.
Attach the sides of the T to backbone extension cables, terminators or
other T connectors – nothing else. All network examples in this docu­ment show networks built with a linear architecture.

Adding a Network Node

You can add a node to any existing connection, anywhere along the net­work backbone. This connection could be 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, separate the sockets of the existing connection
and install the T connector between them.

Use T-connector or double T connector to add
device to bus (maintaining linear architecture)

Backbone cable
to rest of bus

Existing network

Attach
terminator at
end of bus

In this example, a new device is added to the NMEA 2000 bus by install-

ing a T connector between a T connector and a terminator at the end of

the backbone (network bus).

node

Devices connect to
double T connector

If you want to add a node at the end of the backbone (network bus) re­move the terminator from the last connector, like the figure above. In­stall the new T connector and attach the terminator to the side of the
connector.

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