Digi XBee Zigbee Mesh Kit User Manual page 47

1. Add all bytes excluding the start delimiter and the length: 17 + 01 + 00 + 13 + A2 + 00 + 40 + AD + 14 + 2E + FF + FE+ 02 + 44 + 42 = 481
2. From the result, keep only the lowest 8 bits: 81.
3. Subtract that result from 0xFF: FF - 81 = 7E
In this example, 0x7E is the checksum of the frame.
Verify the checksum of a given API frame
1. Add all bytes including the checksum (do not include the delimiter and length).
2. If the checksum is correct, the last two digits on the far right of the sum will equal FF.
Example: Checksum verification
In our example above, we want to verify the checksum is 7E.
Frame Data
Start Delimiter Length Frame type Data
7E 00 0F 17
1. Add all data bytes and the checksum: 17 + 01 + 00 + 13 + A2 + 00 + 40 + AD + 14 + 2E + FF + FE + 02 + 44 + 42 + 7E = 4FF
2. Since the last two far right digits of 4FF are FF, the checksum is correct.
01 00 13 A2 00 40 AD 14 2E FF FE 02 44 42 7E
Checksum