CRC calculation
FC410 with Modbus
Operating Instructions, 02/2016, A5E33120874-AC
147
0x62, 0x66, 0xA6, 0xA7, 0x67, 0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC,
0xAD, 0x6D, 0xAF, 0x6F,
0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68, 0x78,
0xB8, 0xB9, 0x79, 0xBB,
0x7B, 0x7A, 0xBA, 0xBE, 0x7E, 0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C,
0xB4, 0x74, 0x75, 0xB5,
0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71, 0x70,
0xB0, 0x50, 0x90, 0x91,
0x51, 0x93, 0x53, 0x52, 0x92, 0x96, 0x56, 0x57, 0x97, 0x55, 0x95,
0x94, 0x54, 0x9C, 0x5C,
0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B, 0x99,
0x59, 0x58, 0x98, 0x88,
0x48, 0x49, 0x89, 0x4B, 0x8B, 0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F,
0x8D, 0x4D, 0x4C, 0x8C,
0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42, 0x43,
0x83, 0x41, 0x81, 0x80,
0x40
} ;
unsigned short int CRC16(unsigned char *puchMsg, unsigned short int
usDataLen)
{
unsigned char uchCRCHi = 0xFF; /* high byte of CRC initialized */
unsigned char uchCRCLo = 0xFF; /* low byte of CRC initialized */
unsigned uIndex ; /* will index into CRC lookup
table */
while(usDataLen--) /* pass through message buffer */
{
uIndex = uchCRCHi ^ *+ ; /* calculate the CRC */
uchCRCHi = uchCRCLo ^ auchCRCHi[uIndex] ;
uchCRCLo = auchCRCLo[uIndex] ;
}
#ifdef INTEL_LIKE_PROCESSOR
return (unsigned short int)((uchCRCLo << 8) | uchCRCHi);
#else
return (unsigned short int)((uchCRCHi << 8) | uchCRCLo);
#endif
}
See also
There are many ways of calculating a CRC checksum. For further information, please refer
to the Modbus Organisation Website (
) , where detailed descriptions
and programming examples are available.