System Protocols - Raymarine E32158 Installation Instructions Manual

System protocols

Your product can be connected to various products and systems to
share information and so improve the functionality of the overall
system. These connections may be made using a number of
different protocols. Fast and accurate data collection and transfer is
achieved by using a combination of the following data protocols:
• SeaTalk
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• NMEA2000
• NMEA0183
Note: You may find that your system does not use all of the
connection types or instrumentation described in this section.
Seatalk
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SeaTalk (Next Generation) is an enhanced protocol for connection
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of compatible marine instruments and equipment. It replaces the
older SeaTalk and SeaTalk
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SeaTalk utilizes a single backbone to which compatible
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instruments connect using a spur. Data and power are carried within
the backbone. Devices that have a low draw can be powered from
the network, although high current equipment will need to have a
separate power connection.
SeaTalk is a proprietary extension to NMEA 2000 and the proven
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CAN bus technology. Compatible NMEA 2000 and SeaTalk /
SeaTalk devices can also be connected using the appropriate
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interfaces or adaptor cables as required.
NMEA 2000
NMEA 2000 offers significant improvements over NMEA 0183, most
notably in speed and connectivity. Up to 50 units can simultaneously
transmit and receive on a single physical bus at any one time,
with each node being physically addressable. The standard
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protocols.
was specifically intended to allow for a whole network of marine
electronics from any manufacturer to communicate on a common
bus via standardized message types and formats.
NMEA 0183
The NMEA 0183 Data Interface Standard was developed by
the National Marine Electronics Association of America. It is an
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.
AIS350 / AIS650 Installation instructions