CAN RBS

The CAN RBS Module provides a complete CAN restbus simulation. NI-VCOM supports CAN instruments that have their own time management and instruments that depend on software-controlled timing provided by NI-VCOM. The first category has a more precise timing for the restbus simulation. Additionally, it supports the simulation of CAN network management (NM).

Complete a CAN RBS based on the information provided in such an AUTOSAR-XML or .dbc file, which is specified in the Network Descriptor tag of the NI-VCOM configuration.

When using a .dbc file, RBS descriptor XML files provide more RBS information. Create RBS descriptor XML files with the RBSConfig tool (For more information, refer to Using RBSConfig).

Configure the following signals using the RBSConfig tool:
  • Autosignals: Automatically calculated signal values. To configure autosignals using RBSConfig tool, refer to Configuring a Restbus Simulation File. CANs support the following autosignals:
    • Ramp (multiple bits): The bits contain a message counter.
    • Checksum (multiple bits):
      • ChecksumJ1850 (8 Bit)
      • ChecksumJ1850 with User Bytes (8 Bit)
      • Custom Check sum CRC-8
      • ChecksumXOR (8 Bit)
      • ChecksumXOR4Bit (4 Bit)
      • ChecksumAddWithCarry (8 Bit)
      • ChecksumAddAndComplementToOne (8 Bit)
    • Parity (1 bit)
    • Toggle (1 bit)
  • Signal TX_enable: This signal can activate the RBS for message, ECU, and CAN channel.
  • Signal TX_kickout: This signal can send a CAN message immediately.
  • Signal TX_cycletime: This signal can change the cycle time of a message in milliseconds (ms).
  • Signal NM_enable: This signal can activate the NM simulation for the ECU and CAN channel level.
  • Signal NM_sleepInd: This signal can set the sleep indication bit.
  • Signal NM_wakeUp: This signal can wake up the ECU.
It is possible to configure the NM capabilities in the RBSConfig tool. NM signals are only available if the RBSConfig tool enabled NM. Refer to Transmission Modes for information on the different transmission types signals can be sent with.
Note The RBSDescriptor file is not necessarily needed for the CAN RBS. For example, the RBSConfig tool does not support the new AUTOSAR-XML files with the Container-PDU concept (from the AUTOSAR Release v4.2.1).

CAN Message Disassembly with DBC and AUTOSAR XML File

The .dbc and AUTOSAR XML files contain the information for interpreting the raw data from CAN messages received (Rx from the perspective of NI-VCOM) for converting the signal names, values and units. These signal values are available in NI-VCOM for the user interface as ReadOnly signals. You can specify a file for disassembling every CAN port in the Network Descriptor tag. For more information, refer to CAN Configuration.
Note The disassembly of each function module (CAN, LIN, FlexRay, and Automotive Ethernet) adds the following signals as a message level in the NI-VCOM signal tree:
  • RX_time: The signal value corresponds to the current module software time, in seconds, which is configured through the clock_src event source.
  • RX_deltatime: The signal value is calculated from the hardware time stamps, in seconds, of the last two consecutive messages on receive.

CAN-FD

CAN-FD allows you to increase the data bit rate by transferring up to 64 payload bytes in a single message. To activate this function, you must set the Data BitRate parameter in the Configuration Tool. For more information, refer to CAN Configuration.