Lowrance electronic GlobalMap Baja 840C - Manual (Page 26)

18
Expanding to a NMEA 2000 Network
A network bus is an installed and operational network cable (backbone)
running the length of your boat, already connected to a power supply and
properly terminated. Such a bus provides network connection nodes at
various locations around your boat.
The NMEA 2000 network is similar to the telephone wiring in a house.
If you pick up a phone in your living room, you can hear someone talk-
ing into the phone in the bedroom.
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 any network device to the bottom of the "T."
Using our telephone example, the T connectors on the backbone are similar
to telephone 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
must 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 con-
nectors or backbone network cable plugged into one or both sides. Connec-
tions at the end of a network will have the backbone cable or a T connector
plugged into one side and a terminator plugged into the other, as shown in
the following figure.
NMEA 2000 network node located at the end of a NMEA 2000 bus.
T connector
Backbone cable
(to rest of bus)
Cable from
sensor or
display unit
Terminator at
the very end
of the bus