Calculating The Block Check Character - Basler A202K Manual

4.2.3.3 Calculating the Block Check Character

The block check character in any A202
in the descriptor and the data fields. For the write command example shown in Section 4.2.3, the
block check character is 0x45. Let's consider how this block check character was calculated.
In this case, we must find the XOR sum of three bytes. This is done by finding the XOR sum of
the first two bytes and then by taking the result and finding the XOR sum of the result plus the third
byte.
Calculating XOR sums is most easily understood when numbers are shown in their binary form,
so in the sample calculations shown below, the hexadecimal digits in our command have been
converted to binary.
To find the XOR sum of two binary numbers, you must add the two digits in each column using
the following rules:
If both digits are 0, the result is 0.
If both digits are 1, the result is 0.
If one of the digits is a 1 and the other is a 0, the result is 1.
With all of this in mind, here is how the BCC for the write command shown in Section 4.2.3 would
be calculated:
0 1 0 0 0 1 1 0 = the binary representation of 0x46
0 0 0 0 0 0 0 1 = the binary representation of 0x01
0 1 0 0 0 1 1 1 = the XOR sum of the first two bytes
0 1 0 0 0 1 1 1 = The XOR sum of the first two bytes
0 0 0 0 0 0 1 0 = the binary representation of 0x02
0 1 0 0 0 1 0 1 = The XOR sum
0 1 0 0 0 1 0 1 = 0x45 = the block check character
k
BASLER A202
DRAFT
command is the exclusive-or sum (XOR sum) of the bytes
k
Configuring the Camera
4-9