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This command sends the file checksum to the unit.  A simple arithmetic checksum is calculated by adding the characters in the file as binary unsigned 8-bit integers.  The resulting sum is then negated.

Command Syntax



This command not allowed during scenario execution, and will result in the error code “-190,"Execution in progress"”.

The checksum is calculated using the following algorithm, presented here in a Python language example. The array s passed in must be read from a file opened with attributes read and binary (rb).

def cksum(s): 
    sum = 0 
    for c in s: 
        sum += ord(c) 
    sum &= 255 
    sum = -sum 
    return sum

An example in C is shown below.  Again, the char *Data array is read from a file and is a binary array of unsigned 8-bit char values.

unsigned char CalcChecksum(const char *Data, unsigned Length)
    unsigned char sum = 0;
    unsigned char chksum;
    unsigned i;
    for (i = 0; i < Length; ++i) {
        sum += Data[i];
    chksum = -sum;
    return chksum;