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J1939SetChecksumAndCounter

Valid for: CANoe DE • CANoe4SW DE

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Function Syntax

long J1939SetChecksumAndCounter(pg * msg, char[] calculationMethod, dword  counter)

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Description

This function calculates and sets the checksum of the given parameter group as well as the given counter. The available calculation algorithms are described in J1939 Functional Safety – Messages With Integrated Checksum and Counter.

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Parameters

  • msg: The parameter group to calculate and set the checksum for.
  • calculationMethod: Two letters in the form [A-E][a-f] (e.g. “Bc”) that define the calculation rule and position of the checksum and message counter.
  • counter: Current message counter to be set in the given parameter group.

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Return Values

  • 0: Checksum successfully filled.
  • -1: Error: calculation method is invalid.

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Example

on key 'a'
{
  long err;
  pg * msg;
  dword counter = 0;

  msg.PGN = 0xF123; //DCDC4OS
  msg.SA = 0x1;
  msg.dlc = 8;
  msg.byte(0) = 0x01;
  msg.byte(1) = 0x02;
  msg.byte(2) = 0x03;
  msg.byte(3) = 0x04;
  msg.byte(4) = 0x05;
  msg.byte(5) = 0x06;
  msg.byte(6) = 0x07; // Bits 4-8 will be overwritten with the message counter
  msg.byte(7) = 0x08; // Will be overwritten with the checksum

  if(J1939SetChecksumAndCounter(msg, "Aa", counter) != 0)
  {
    write("Error while setting checksum and counter");
  }
  counter = (counter + 1) % 16;
  output(msg);
}