The Checksum
11 Bytes input: << Hex 02 + 359,99 + Hex 17 + 06 + Hex 24
In case of correct input length and plausible syntax, the checksum provides some additional transmission security. It is computed as a byte by byte XOR concatenation.
Hex 02 XOR '3' XOR '5' XOR '9' XOR ',' XOR '9' XOR '9' XOR Hex 17
or with completely hexadecimal notation:
02 XOR 33 XOR 35 XOR 39 XOR 2C XOR 39 XOR 39 XOR 17 = 06
The checksum is now transmitted ASCII coded. So 2 bytes are send: '0' and '6'