Lowrance General information Pamplet Configuration guide

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Pub. 988-0154-172
Setup and Installation of
NMEA 2000Networks
General Information
NMEA 2000 is a communication bus network specifically designed for
boats. This is an industry standard developed by the National Marine
Electronics Association(NMEA). To help you get the most out of this
technology Lowrance has introduced a line of products that can com-
municate over a NMEA 2000 network.
This instruction sheet outlines the basics of what it takes to create a
NMEA 2000 network. It also will explain how to use this network to
connect your Lowrance and LEI products and provide some tips on con-
figuring and using the operational network.
Terminology
There are several key phrases you will need to know before we can ex-
plain how the NMEA 2000 system works. Some of these are technical
terms, some of them are names taken from the NMEA 2000 standard
and some of them are our own names developed for clarity. All of them
will help you understand what we are saying.
"NMEA 2000Network" or "LowranceNET"
When we talk about the NMEA 2000 network we are talking about the
communications link between two or more devices that transfer NMEA
2000 information. "LowranceNET" is the NMEA 2000 networking sys-
tem developed by Lowrance Electronics. Think of this as a computer
network or the phone wiring in your house. If you pick up a phone in
your living room you can hear someone talking into the phone in the
bedroom.
A NMEA 2000 network is a way to let more than one display unit "lis-
ten in" on the GPS antenna's conversation or to let more than one sonar
display unit overhear the messages being sent by a temperature sensor.
You can even view engine diagnostics and fuel level on digital gauges or
display units located anywhere on your boat.
If you have a Lowrance display unit with an LGC-2000 GPS module
installed then you have a NMEA 2000 network. The connectors and
cables that came with your LGC-2000 actually function as a dedicated


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NMEA 2000 network passing GPS signal information along the net-
work (that is, the extension cables) to the GPS display unit. This is a
very limited application of the term "network."
The other end of the scale is a network bus (described in the following
segment) built into your boat with nodes at intervals allowing you to
connect several GPS or sonar display units, temperature or water speed
sensors, digital gauges or any other NMEA 2000 device.
Such a network could display the temperature readings from two dif-
ferent sensors (one at the water surface and another in your live well)
as well as the GPS signal from an LGC-2000 and even the reading from
a fuel-flow sensor attached to your fuel line. The network could share
all of this information with a sonar-GPS combo display unit mounted in
the dash, a smaller sonar-only display unit at the stern and another up
on the bow by your trolling motor. All three display units attached to
the bus would have access to all of the sensor information from every
accessory attached to the network. The network design would look like
the one in the following diagram.
NMEA 2000 network with three sonar or sonar-GPS combo display
units, each receiving position information from the LGC-2000, tempera-
ture information from temp sensors at two different locations and fuel
use information from a fuel flow sensor.
Sonar-GPS
unit in dash
LGC-
2000
EP-35 temp sensor
in live well
EP-35 temp sensor
at water surface
Sonar unit
at bow
Sonar unit
at stern
EP-10 fuel flow sensor
25' extension
cable

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That is the advantage of a NMEA 2000 network. Every display unit,
gauge or sensor attached to the network communicates with all the others.
Of course location, speed and temperature are not the only kinds of infor-
mation that can be shared. Other capabilities include the ability to share
the amount of fuel remaining in your tanks, detailed engine information
such as oil pressure and fuel efficiency and much more.
NOTE:
You probably noticed there is no transducer mentioned in that list or
anywhere else in this document. The full sonar chart reading from a
transducer takes too much bandwidth for a NMEA 2000 network
which means sonar charts cannotbe shared. Every sonar display
unit requires its own transducer to draw charts.
However, if you have a sonar display unit (with a working trans-
ducer) connected to the NMEA bus it will share the digital depth
with every other display unit on the network.
"NMEA 2000 Bus" or "Network Bus"
Technically, any physical cable properly installed and used to transfer
network information is a "network bus" but in our documentation we
use this term to refer to the standard manufacturer installation ap-
pearing in new boats. This network bus is an installed and operational
network cable running the length of your boat, already connected to a
power supply and properly terminated. Such a bus provides network
nodes at various locations around your boat.
"Network Backbone" and "Network Nodes"
A network bus is built of network nodes spread along a backbone. Net-
work 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.
If we stick with the earlier example, the T connectors along the length of
a boat are the equivalent of phone jacks spread throughout a house.
Phones in a home have to 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. The backbone is like the phone wiring
that runs throughout a home; it connects these nodes.
Connections found in the middle of the bus will have one or more of these T
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.

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NMEA 2000 network node located at the end of a NMEA 2000 backbone.
All of the T connectors on your boat's network will probably be filled but
if you want to add another node to a working network just add a T con-
nector 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 making the process even easier.
This T connector allows you to add a device to your NMEA 2000 bus
creating a network node.
The "soft" T connector, shown above with a "hard" T connector, is another
option for connecting devices in a NMEA 2000 network. The soft T works
the same as a hard T. The soft T is used to install a network node in areas
were a hard T will not fit.
Backbone cable
(to rest of bus)
Cable from
sensor or
display unit
LEI or Lowrance
device needs an
open T.
Terminator at
the very end
of the bus

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"Linear Architecture"
NMEA 2000 networks are designed using a linear architecture and it is
important for you to maintain this pattern whenever you modify your
network (such as adding nodes).
When we say "linear architecture" we are referring to the way the net-
work's backbone is assembled and to the way you attach T connectors
along it. Note that every T connector has one female socket and two male
sockets. This means you could connect it in two different ways.
You could plug the sensor or display unit into the bottom of the T and
the backbone cable into the side of the T (as we recommend). You could
also plug the sensor or display unit into the side of the T and the back-
bone connection in the bottom of the T. The sockets would allow you to
make that connection but you would lose linear architecture. Consider
the following images.
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 of the network designs in these images contain the same set of
components. Both networks are terminated and all of the connectors
are able to attach together. However, the design on the left is easier to
maintain and expand. It also allows you to make sure the two termina-
tors are at the ends of the backbone. Since the system on the right is
non-linear there is not a clear end.
Always maintain linear architecture when modifying your network.
Just make sure to attach display units or sensors to the bottom of the T.
Attach the sides of the T to other T connectors, to backbone extension
cables or to terminators – nothing else.
LGC-
2000
LGC-
2000
EP-35
tem
p
sensor
EP-35
temp sensor
Sonar or GPS
display unit
Sonar or GPS
display unit
Correct architecture Incorrect architecture

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For reference purposes all of the example network designs you will find
in this document show networks built with a linear architecture.
Adding a Network Node
You can add a node anywhere along the network backbone where a con-
nection already exists. This connection could be at the end of the network
(between a T connector and a terminator) between two T connectors, be-
tween a T connector and a backbone extension cable or between two ex-
tension cables. Wherever you want to add the new node simply separate
the sockets of the old connection and attach your new T connector be-
tween them.
Add a new device to a NMEA 2000 bus by attaching a T connector be-
tween two T connectors, between a T connector and the end terminator,
or between two backbone extension cables.
If you want to add a node at the end of the line (as shown in the previous
figure) remove the terminator from the very last connector, securely at-
tach the new T connector, and attach the terminator on the new connec-
tor. Either method will allow you to add a device.
NOTE:
If your network only includes one terminator (such as the network
created when a single display unit is connected to an LGC-2000)
you will need to add a Node Kit before you can add additional net-
work nodes. You only need to purchase a Node Kit once. After that
you can add nodes as described in the previous section.
Most manufacturer-installed networks will already have two ter-
minators so a Node Kit will not be necessary.
Adding an Extension Cable
LEI provides LowranceNET extension cables in various lengths so that
you can position all of the items on your network exactly where you want
Existing network
node Attach
terminator at
end of bus.
Add T-shaped con-
nector to add device
to bus (maintaining
linear architecture).
Lowrance or LEI device con-
nects to new T connector.

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them on your boat. Every extension cable has a male connector on one
end and a female connector on the other allowing you to insert it any-
where the network has a connection.
For instance, you might have a cluster of T connectors at the bow of your
boat and attached to the last T on the cluster is a 15' extension cable
running to your console. On the end of this extension cable you could
have another cluster of T connectors and another extension cable run-
ning to the stern of the boat where you have more T connectors for more
devices. We recommend you keep your network backbone to less than
about 300 feet (100 meters).
You can also attach an extension cable between a device on the network
and the T connector allowing you to more easily position the device right
where you want it. You should never use more than 15' (about 5 meters)
of extension cable between a device and the network backbone.
Building a LowranceNET NMEA 2000 Network
In 2005, the original equipment manufacturers (OEM) began installing
NMEA 2000 networks as standard equipment in new boats. If your boat
does not have an OEM-installed NMEA 2000 network you will have to
install your own. This instruction sheet will explain how to install a
LowranceNET NMEA 2000 network using cables available from LEI.
Installing a NMEA 2000 network is not complicated. If you can grasp a
few essential concepts you can design a network to fit your needs and
keep it running smoothly.
Power
In order for a NMEA 2000 network to operate the bus must be con-
nected to a switched power source (a power source that you can turn on
and off – generally a switch on your boat's accessory panel). NMEA
2000 networks require 12 volts DC power. If your boat came with a
NMEA 2000 bus it should already be connected to a switched power
source that draws from the boat's battery. To confirm how the bus was
installed, consult your boat dealer or manufacturer.
•No matter how large or small the network, no matter how many
devices are sharing information along it, a NMEA 2000 network
must be connected to a 12-volt power source to operate.
If you are only running a display unit and an LGC-2000 on the mini-
network as described earlier you will still have to connect the display
unit's NMEA 2000 Power cable to a switched power source in order to
power the network.

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•Always use a switched power source for your NMEA 2000 bus. Do
not connect the NMEA 2000 Power cable directly to your boat's battery.
You need to be able to turn the network's power on and off.
Typical do-it-yourself NMEA 2000 power configuration, using the 3-
branched power/data cable packed with the display unit.
Many of the devices on the NMEA 2000 bus are "on" and drawing cur-
rent whenever the network has power – they do not have their own
on/off switches. In order to preserve your battery you need to make sure
your NMEA bus's main power supply can be switched on or off easily.
Most installations simply connect the NMEA power cable to a switch on
the boat's accessory panel.
•Never connect an additional power source to a NMEA 2000
bus that is already powered. A NMEA 2000 network should
never be connected to more than one power source.
If you are attaching a GPS display unit and an LGC-2000 to an already
powered NMEA 2000 bus make sure you do not connect the display
unit's NMEA 2000 Power cable to another power source.
All Lowrance display units with blue connectors come packed with a
three-branched power/data cable that includes wires to power a NMEA
2000 bus. As stated before, if you are connecting just a display unit and
an LGC-2000 as a dedicated network you will have to attach the NMEA
2000 power cable to a switched power source. Note that this is in addi-
tion to the display unit's own power cable which can be connected di-
rectly to your boat's battery.
However, it is possible to hook up several sonar or GPS display units to
a single network. If you do remember that only one display unit
Sonar unit's power
cable can connect
directly to battery
NMEA 2000 power cable should connect to switched power.
Only connect the NMEA 2000 power cable for
one display unit.
Data
cable
Extension cable
To network
T connector

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should provide power to the network. Even though all the display
units on the network come with a NMEA 2000 Power cable you should
only attach one of them.
In addition to the three-branched power/data cable that comes with
Lowrance display units Lowrance and LEI provide two other methods of
powering a NMEA 2000 bus. These include a Powered Terminator and a
Power Node. Many manufacturer-installed networks use one of these al-
ternate power sources. If your network already includes either of these
power sources do not connect the NMEA 2000 power cable of any of your
GPS or sonar display units.
OEM factory installations typically use a Power Node to supply power
to the network bus. The red and black leads are connected to a
switched power source, allowing the user to turn off power to the bus.
WARNING!
If you connect multiple power sources to a NMEA 2000
network you could cause severe damage to the network,
attached devices and your boat!
Terminators
In order for it to work properly, a NMEA 2000 network needs to be
terminated with either a single 60-ohm terminator or two 120-ohm
terminators. The most common and preferred setup uses two 120-ohm
terminators – one at each end of the bus. This must be used if you in-
tend to use three or more devices on the bus.

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If you have an LGC-2000 you have seen the small plug (with "60" im-
printed in the plastic grip) that comes along with the T connector and ex-
tension cables. This little plug is as important to the mini-network as any
of the other parts – this is the one 60-ohm terminator. If your boat came
with an installed NMEA 2000 bus the terminators will already be at-
tached.
The terminators provide resistance necessary for devices to communi-
cate along the network. This communication takes the form of electrical
pulses sent out by the device transmitting information. In order for the
network to operate you need 60-ohms of resistance to pull the network
back to its recessive state after a signal so the next pulse can be heard.
Terminators (either one 60-ohm terminator or two 120-ohm termina-
tors in parallel) are used to create this resistance.
•Never attach terminators to an operational NMEA 2000 net-
work bus. If it is working it is already terminated.
•If you are using two 120-ohm terminators it is best to connect them
to sockets on the network as far from each other as possible. Attach
one at each end of the backbone and install all of the network nodes
between them.
Setting up a Network
Lowrance and LEI provide all the cables you will need to create a NMEA
2000 network on your boat. We provide T connectors and extension ca-
bles so you can add devices along the backbone wherever you want. Once
you have a working network every sensor you add to it will come with its
own T connector for easy expansion.
Remember that one of the simplest LowranceNET NMEA 2000 networks
is just a display unit with an LGC-2000, one T connector and one 60-ohm
terminator. We will show you how to connect that system in the follow-
ing image.
LGC-2000 direct connection to a display unit.
Extension cable
LGC-
2000
Attach the LGC-
2000 to the side of
the T connector, for
this setup
only .
Network port on
display unit
60-ohm
terminator