crc_modbus( input_str, num_bytes );
Parameters
| Parameter | Type | Description |
|---|---|---|
input_str |
const unsigned char * |
The input byte buffer for which the CRC must be calculated |
num_bytes |
size_t |
The number of characters in the input buffer |
Return Value
| Type | Description |
|---|---|
uint16_t |
The resulting CRC value |
Description
The function crc_modbus() calculates a 16 bit CRC value of an input byte buffer based on the CRC calculation algorithm used by the Modbus protocol. The buffer length is provided as a parameter and the resulting CRC is returned as a return value by the function. The size of the buffer is limited to SIZE_MAX.
The Modbus CRC calculation uses the same polynomial as the standard CRC-16, but with a different initialization value.