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TMS570LS3137: About CAN2 Information Redundancy Techniques

user4777395
Intellectual 480 points
Part Number: TMS570LS3137

About Information Redundancy Techniques,

Does this mean to guarantee the contents of communication by attaching checksum data or increment data to the CAN frame according to the importance of the data in addition to the CRC of the CAN protocol?

  • 0
    TI__Guru 59540 points

    The definition according to IEC61508-7 Ed.2 2010-4:

    this mechanism is independent of the in-message CRC that is part of the CAN protocol. The out of message CRC/Checksum could be over just a subset of the the 8 bytes within the CAN message or could be over several sequentially received packets with one having the transmitted CRC that needs to be matched. Given this is on active CAN transmissions, the methodology would have to be supported on a system wide/application dependent scheme. The key is that it would be/should be an out of message calculation/checksum.

  • 0 in reply to Chuck Davenport
    Intellectual 480 points
    I understood that it corresponds at the application level.

    I am confused without understanding the following two differences.
    · Information Redundancy Techniques
    · Transmission Redundancy
  • 0 in reply to user4777395
    TI__Guru 59540 points
    Transmission Redundancy is the process of duplicating the data and presenting it serially. This gives diversity in time which helps to detect transient faults given the second transmission is unlikely to be affected by another random corrupting influence (cosmic radiation, cross talk, noise, etc.) in the same way as the first transmission.

    Information redundancy, uses the same information redundantly to check for errors. For example, node A calculates a CRC over the data within a packet payload and inserts the calculated CRC value in the payload as well. Node B receives the packer and payload and, upon receipt, calculates the CRC independently of node A using the same data (redundant information). The resulting CRC calculated by node B is then compared to the value calculated by node A. You could also use parity for a similar information redundancy technique (parity is less effective though) or some more complex algorithm such as an MD5 hash where node A encodes the data and node B decodes it.