Notes about this standard. Buying it costs 4000 or maybe 8000 USD, if they feel like selling it to you. NMEA standard order form

CAN Boat - Open source, reverse engineered NMEA 2000 tools. https://canboat.github.io/canboat/canboat.html

Old but official info

https://www.maretron.com/products/pdf/Network%20Installation%20Guide.pdf

https://actisense.com/wp-content/uploads/2021/08/Complete-Guide-to-NMEA-2000_Revision_4_2021.pdf

List of some PGNs from NMEA

NMEA-2000 Networks and Modern Outboard Engines

https://www.csselectronics.com/pages/nmea-2000-n2k-intro-tutorial#nmea-2000-vs-j1939-vs-isobus

Physical layer is based on DeviceNet, notable the Micro-C connectors.

PGNs are what they call message types, or what defines the meaning of the message body. They form part of the 29 bit CAN ID. NMEA200 can carry PGNs from the SAE J1939 standard, used for road vehicles. These messages may come from engines on a boat. Looks like NMEA2000 is actually an extension of J1939, or rather close to it.

120 Ohms on each end.

Devices are supposedly required by the standard to NOT contain terminators.