Raymarine E90W, Installation Instructions Manual

Page: 18 / 104

international standard to enable equipment from many different
manufacturers to be connected together and share information.
The NMEA 0183 standard carries similar information to SeaTalk.
However it has the important difference that one cable will only
carry information in one direction. For this reason NMEA 0183 is
generally used to connect a data receiver and a transmitter together,
e.g. a compass sensor transmitting heading to a radar display. This
information is passed in ‘sentences’, each of which has a three
letter sentence identifier. It is therefore important when checking
compatibility between items that the same sentence identifiers are
used some examples of which are:
• VTG - carries Course and Speed Over Ground data.
• GLL - carries latitude and longitude.
• DBT - carries water depth.
• MWV - carries relative wind angle and wind speed data.
NMEA baud rates
The NMEA 0183 standard operates at a number of different
speeds, depending upon the particular requirement or equipment
capabilities. Typical examples are:
• 4800 baud rate. Used for general purpose communications,
including FastHeading data.
• 9600 baud rate. Used for Navtex.
• 38400 baud rate. Used for AIS and other high speed applications.
2.5 Data master
Any system containing more than one networked multifunction
display must have a designated data master.
The data master is the display which serves as a primary source
of data for all displays, it also handles all external sources of
information. For example the displays may require heading
information from the autopilot and GPS systems, usually received
through a SeaTalk
ng or NMEA connection. The data master is the
display to which the SeaTalk, NMEA and any other data connections
are made, it then bridges the data to the SeaTalk
hs network and
any compatible repeat displays. Information shared by the data
master includes:
• Cartography
• Routes and waypoints
• Radar
• Sonar
• Data received from the autopilot, instruments, the engine and
other external sources.
Your system may be wired for redundancy with data connections
made to repeat displays. However these connections will only
become active in the event of a fault and/or reassignment of the
data master.
18 E-Series Widescreen installation