SMART2 CAN bus

The SMART2 supports the transmission of NMEA2000 messages over the CAN bus.

By default, CAN is disabled on the SMART2. Critical CAN configuration parameters such as Parameter Group Numbers (PGNs), addresses and priorities are system-specific and must be explicitly configured.

The addresses and PGNs are typically allocated when the overall CAN bus topology is determined. A Node has a unique CAN J1939 NAME and address.

The SMART2 has internal CAN transceivers, however they still require proper bus terminations.

With an Advanced CAN Bus (-C) software model on the SMART2, CAN messages can also be read from or written to a CAN port using OEM7 commands and logs. This is typically implemented using the NovAtel API. For more information refer to Using Lua to access I/O devices connected to the receiver. Note that if NMEA protocol is enabled using the CANCONFIG command, the user CAN access commands will be rejected.

Refer to Table: SMART Antenna interface cable connector pinout for pin-out information.

The SMART2 supports the following NMEA2000 Parameter Group Messages (PGN) over the CAN bus:

  • PGN 126992 System Time

  • PGN 127250 Vessel Heading

  • PGN 127251 Rate of Turn

  • PGN 129025 GNSS Position Rapid Update

  • PGN 129026 COG & SOG Rapid Update

  • PGN 129027 Position Delta High Precision Rapid Update

  • PGN 129028 Altitude Delta, Rapid Update (available on OEM 7.08.15 and greater firmware)

  • PGN 129029 GNSS Position

  • PGN 129551 GNSS Differential Signal

The SMART2 also supports the following J1939-71 Parameter Group Message (PGN) over the CAN bus: (OEM 7.08.15 firmware only)

  • PGN 65256 Vehicle Direction and Speed (requires a valid, converged SPAN solution)

The following commands and logs are used for CAN configuration:

  • CANCONFIG command: controls the CAN transceiver hardware and places the receiver on bus or off bus

  • J1939CONFIG command: assigns the CAN J1939 NAME and address parameters to a Node

  • J1939STATUS log: reports the status a Node on the J1939 CAN network, such as the claimed address

  • LOG CCOMx PGNabcd: configures the NMEA2000 messages

    CCOM ports with a lower port number have a higher transmission priority.

For information about these commands, see the OEM7 Commands and Logs Reference Manual.

When the NMEASOLUTIONSOURCE is set to ANTENNA, the Vessel Heading and Rate of Turn are sourced from RTKHeadingSolutionDP, resulting in a delay between the time the rover receives the data and when the time-synchronized PGN messages are published associated to the ALIGN functionality requirement. For example, when the PGNs are logged at 10 Hz the delay may be up to 100ms and vary depending on the ALIGN corrections update rate set. Conversely, when the NMEASOLUTIONSOURCE is set to INS, the Vessel Heading and Rate of Turn are sourced from NMEAAzimuthSolutionDP, eliminating any significant delay between data provision and publication.

Details for the PGN messages can be found in the NMEA2000 specification which can be purchased directly from the National Marine Electronics Association (www.nmea.org/).

Default configuration

After a FRESET, the receiver has the following CAN configuration:

  • The CAN physical port is disabled

  • No J1939 addresses are claimed

  • The CCOM1 port is configured for NMEA2000 messages only

Default NAME

Parameter

Value

Address

0x1C

Industry Group

2

Device Class

0

Device Class Instance

0

Function

23

Function Instance

0

ECU Instance

0

Manufacturer Code

305