CAN BUS Questions

A couple of CAN BUS Questions:

When I see drawings with CAN 1 and CAN 2, are these different systems? Or, is this a redundant system? What is the use of two Bus?

Is the CANBUS for "car, private" compatible with a NMEA 2000 system? Is there a way to share information between two such systems?

Your help is appreciated.

 

be aware NMEA 2000 is a can bus and they all suffer single point failure hence never used on commercial vessels, saying that a great plug and play system for pleasurecraft
Equipment is either nmea 2000 compliant or not.
Most pleasure boat electronic companies have their own standard but do supply gateways to get back to nmea 2000 and nmea 0183

 

CAN is an bus comunication system. J1939 is an automotive standard using the CAN layer. If you want redundancy you need two CAN lines (CAN1 and CAN2)
NMEA2000 has it's own standard inside the CAN-bus layer and you need to pay big *** cash to get a copy of the text describing the standard.
The good old NMEA you just read simple strings trough 422 using standard software.