NMEA 2000 is a
combined electrical and data specification for a marine
data network for communication between marine electronic
devices such as
depth finders,
nautical chart plotters,
navigation instruments,
engines, tank
level sensors, and
GPS receivers. It has been defined by, and is controlled
by, the US based
National Marine Electronics Association (NMEA).
NMEA 2000 connects devices
using
Controller Area Network (CAN) technology originally
developed for the auto industry. NMEA 2000 is based
on the SAE
J1939 high-level protocol, but defines its own messages.
NMEA 2000 devices and J1939 devices can be made to co-exist
on the same physical network.
NMEA 2000 (IEC
61162-3) can be considered a successor to the
NMEA 0183 (IEC 61162-1) serial data bus standard.
It has a significantly higher data rate (250k bits/second
vs. 4800 bits/second for NMEA 0183). It uses a compact
binary message format as opposed to the ASCII
serial communications protocol used by NMEA 0183.
Another improvement is that NMEA 2000 supports a disciplined
multiple-talker, multiple-listener data network whereas
NMEA 0183 requires a single-talker, multiple-listener
(simplex)
serial
communications protocol. One of the leading manufacturers
of marine-equipment,
Raymarine, uses SeaTalk 2 which is highly
compatible with NMEA 2000.
