Have you looked at http://en.wikipedia.org/wiki/NMEA_2000 ?



> I need to read data from a John Deere GPS. The GPS doesn't use the
> traditional RS-232 interface with NMEA protocol, but instead it uses a
> CAN bus at 250kbps and sends GPS data in NMEA2000 format inside CAN
> packets.
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> The CAN BUS is populated by the GPS, a monitor and an auto-pilot.
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> I got Bosch's documentation on CAN BUS (free) and also ISO 11783
> standards. Interestingly, Bosch published their invention for free, then
> comes ISO, adopts it and starts selling the documentation :(
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> Somewhere in ISO 11783-* I found that the NMEA 2000 messages are
> standardized as IEC 61162-3.
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> I bought standard IEC 61162-3 for US$177.00 in the hope that it would
> detail the packets' structures and data types, but it revealed to be a
> very general overview of the protocol and doesn't give any pointers to
> which other documents detail each message.
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> I simply can't afford buying all the related standards to try to find
> the one I need.
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> I sniffed the CAN bus with a Saleae's Logic and an Atmel ATSAM3X-EK, and
> captured a lot of traffic. Below are the CAN IDs of some of the packets:
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> 83885952
> 218103594
> 419429139, 419430163
> 484910620
> 218034972, 218031644, 218032156, 351240220, 218103580, 419430172,
> 150994716
> 484900646, 486538790
> 419430354
> 485162790
> 217022492
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>=20
> Does someone know anything about NMEA 2000, and more specifically
> NMEA
> 2000 over CAN BUS?
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>=20
> Thanks,
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> Isaac
>=20
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