J1939 is a Society of Automotive Engineers (SAE) networking standard that is similar to NMEA 2000. Both network protocol standards are based on the same hardware called Controller Area Network (CAN) and both protocols use the same message format. The difference between J1939 and NMEA 2000 is that the SAE developed a message set for the automotive industry while the National Marine Electronics Association (NMEA) developed a message set for the marine industry. For example, J1939 has many messages for engine parameters like engine speed, oil pressure, and coolant temperature while NMEA 2000 messages typically describe things like longitude, latitude, depth, and speed through water.