Glossary
Parameter Group Number (PGN): Term Parameter Group Number (PGN) is used to refer to the 18-bit group of the Reserve bit, DP, DF and PS, which have been marked with blue on the table above.
The biggest difference between J1939 and NMEA 2000, in addition to the marine-specific messages, is that in J1939 the device and sensor IDs are hard-coded whereas in NMEA 2000, the addresses are negotiated when a new device joins the network. This makes NMEA 2000 a plug-and-play -type network. Majority of NMEA 2000 and J1939 messages are of a broadcast-type with no destination address specified. Because of this, no request-type messages are needed.