Gustavo González / SimpleModbusSlave

SimpleModbusSlave allows you to communicate to any slave using the Modbus RTU protocol. The crc calculation is based on https://os.mbed.com/users/jpelletier/code/CRC/ The functions implemented are functions 3 and 16. read holding registers and preset multiple registers of the Modbus RTU Protocol. This implementation DOES NOT fully comply with the Modbus specifications.

lib_crc.cpp@1:85e226914fb7, 2017-10-25 (annotated)

Committer:
gugani
Date:
Wed Oct 25 10:38:11 2017 +0000
Revision:
1:85e226914fb7
Parent:
0:7c5265097fd2 
Initial commit

Who changed what in which revision?

UserRevisionLine numberNew contents of line
gugani 0:7c5265097fd2 1 #include <stdint.h>
gugani 0:7c5265097fd2 2
gugani 0:7c5265097fd2 3 const uint16_t crc_tab_8005_reflected[] =
gugani 0:7c5265097fd2 4 {
gugani 0:7c5265097fd2 5 0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
gugani 0:7c5265097fd2 6 0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
gugani 0:7c5265097fd2 7 0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
gugani 0:7c5265097fd2 8 0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
gugani 0:7c5265097fd2 9 0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
gugani 0:7c5265097fd2 10 0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
gugani 0:7c5265097fd2 11 0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
gugani 0:7c5265097fd2 12 0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
gugani 0:7c5265097fd2 13 0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
gugani 0:7c5265097fd2 14 0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
gugani 0:7c5265097fd2 15 0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
gugani 0:7c5265097fd2 16 0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
gugani 0:7c5265097fd2 17 0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
gugani 0:7c5265097fd2 18 0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
gugani 0:7c5265097fd2 19 0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
gugani 0:7c5265097fd2 20 0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
gugani 0:7c5265097fd2 21
gugani 0:7c5265097fd2 22 0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
gugani 0:7c5265097fd2 23 0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
gugani 0:7c5265097fd2 24 0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
gugani 0:7c5265097fd2 25 0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
gugani 0:7c5265097fd2 26 0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
gugani 0:7c5265097fd2 27 0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
gugani 0:7c5265097fd2 28 0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
gugani 0:7c5265097fd2 29 0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
gugani 0:7c5265097fd2 30 0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
gugani 0:7c5265097fd2 31 0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
gugani 0:7c5265097fd2 32 0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
gugani 0:7c5265097fd2 33 0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
gugani 0:7c5265097fd2 34 0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
gugani 0:7c5265097fd2 35 0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
gugani 0:7c5265097fd2 36 0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
gugani 0:7c5265097fd2 37 0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040
gugani 0:7c5265097fd2 38 };
gugani 0:7c5265097fd2 39
gugani 0:7c5265097fd2 40 uint16_t update_crc16_reflected(const uint16_t *table, uint16_t crc, char c )
gugani 0:7c5265097fd2 41 {
gugani 0:7c5265097fd2 42 uint16_t short_c;
gugani 0:7c5265097fd2 43
gugani 0:7c5265097fd2 44 short_c = 0x00ff & (uint16_t) c;
gugani 0:7c5265097fd2 45
gugani 0:7c5265097fd2 46 /* Reflected form */
gugani 0:7c5265097fd2 47 return (crc >> 8) ^ table[(crc ^ short_c) & 0xff];
gugani 0:7c5265097fd2 48 }
gugani 0:7c5265097fd2 49
gugani 0:7c5265097fd2 50
gugani 0:7c5265097fd2 51 uint16_t update_crc16_A001( uint16_t crc, char c )
gugani 0:7c5265097fd2 52 {
gugani 0:7c5265097fd2 53 return update_crc16_reflected(crc_tab_8005_reflected,crc,c);
gugani 0:7c5265097fd2 54 }
gugani 0:7c5265097fd2 55
gugani 0:7c5265097fd2 56
gugani 0:7c5265097fd2 57 uint16_t calculate_crc16_Modbus(char *p, unsigned int length)
gugani 0:7c5265097fd2 58 {
gugani 0:7c5265097fd2 59 uint16_t crc;
gugani 0:7c5265097fd2 60 unsigned int i;
gugani 0:7c5265097fd2 61
gugani 0:7c5265097fd2 62 crc = 0xFFFF;
gugani 0:7c5265097fd2 63
gugani 0:7c5265097fd2 64 for (i=0; i < length; i++)
gugani 0:7c5265097fd2 65 {
gugani 0:7c5265097fd2 66 crc = update_crc16_A001(crc,*p++);
gugani 0:7c5265097fd2 67 }
gugani 0:7c5265097fd2 68 return crc;
gugani 0:7c5265097fd2 69 }
gugani 0:7c5265097fd2 70
gugani 0:7c5265097fd2 71