CRC verification
CRC residue explained
Understand the residue constant and how complete codewords can be checked without separating data and CRC.
6 min read
What residue represents
The residue is a model-specific constant associated with processing a valid message together with its correctly encoded CRC. It can be used to verify a complete received codeword.
Why residue tests can be confusing
The CRC bytes must be appended in the correct order and representation. Reflection, final XOR and byte order determine what bytes are actually transmitted, so simply appending the displayed hexadecimal number may not reproduce the published residue.
Check value and residue serve different purposes
The check value validates the model using a standard input. The residue validates the handling of a full message plus its CRC field. A robust implementation can test both.
Try it in the calculator
Change CRC parameters and compare standard algorithm results using the browser-based calculator.