giúp đỡ modbus với pic

[tiger-lion]

chào các huynh, em viết chương trình modbus RTU slave trên pic16f877a nhưng crc gửi đi ko đúng, em có tham khảo cách tính crc trong tài liệu http://forums.ni.com/attachments/ni/...I_MBUS_300.pdf .

huynh nao làm rồi giúp em xem sai ở đâu.

trình tự em test như sau :


Modbus Master send:

0x01 address Slave
0x04 function 4
0x00 address start byte hight
0x01 address start byte low
0x00
0x04 quantity
0xA0 crc hight
0x09 crc low



Modbus Sleve Respond: (pic16f877a)

01 04 08 00 00 00 00 00 00 00 00 40 0B


huynh nào có cách tính crc khác chỉ giúp em với ạ

[tiger-lion]

#include <16F877A.h> 
#fuses HS, NOWDT ,PROTECT ,NOBROWNOUT ,NOPUT 
#use delay(clock=20000000) 
#use rs232(baud=9600, xmit=PIN_C6,rcv=PIN_C7,bits=8, stop=2, parity=N)





int1 modbus_flag_status; 

int8 modbus_index = 0; 
int8 modbus_data_transmit[10];
int8 modbus_data_reciever[10]; 

//---------------------------------------
int16 modbus_calcu_crc(int8 *puchMsg, int16 usDataLen);
//---------------------------------------
void main()
{
   int8 i ; 
   int8 quantity ; 
   int16 modbus_crc ; 
   
   
   enable_interrupts(INT_RDA);
   enable_interrupts(GLOBAL);

   for(i=0;i<10;i++ )
   {
      modbus_data_transmit[i] = 0; 
   };


   while(TRUE)
   {
     
     if( modbus_flag_status == 1 )    // test function 4  
     {
         modbus_flag_status = 0; 
         
         
         putchar( modbus_data_reciever[0]);    // adress slave 
         putchar( modbus_data_reciever[1]);    // function 
         
         quantity = modbus_data_reciever[5]*2 ;  
         
         putchar(quantity);                    // byte count 
         
         for(i=0;i<quantity;i++)
         {
            putchar( modbus_data_transmit[i] );  // data byte
         };
         
         
         modbus_crc = modbus_calcu_crc(modbus_data_transmit, quantity); // crc calculate
         
         putchar( modbus_crc >> 8 );   // crc hight byte
         putchar( modbus_crc);         // crc low   byte 
     
     };
     
      
   }
}
//-----------------------------------------------------------
int16 modbus_calcu_crc(int8 *puchMsg, int16 usDataLen)
{


//---------------------------------------
/* Table of CRC values for high–order byte */
const unsigned char modbus_CRCHi[] = {
0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,
0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,
0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,
0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,
0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,
0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,
0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,
0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,
0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,
0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,
0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,
0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,
0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,
0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x01,0xC0,
0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,
0xC0,0x80,0x41,0x00,0xC1,0x81,0x40,0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,
0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x01,0xC0,0x80,0x41,0x00,0xC1,0x81,
0x40
};

/* Table of CRC values for low–order byte */
const unsigned char modbus_CRCLo[] = {
0x00,0xC0,0xC1,0x01,0xC3,0x03,0x02,0xC2,0xC6,0x06,0x07,0xC7,0x05,0xC5,0xC4,
0x04,0xCC,0x0C,0x0D,0xCD,0x0F,0xCF,0xCE,0x0E,0x0A,0xCA,0xCB,0x0B,0xC9,0x09,
0x08,0xC8,0xD8,0x18,0x19,0xD9,0x1B,0xDB,0xDA,0x1A,0x1E,0xDE,0xDF,0x1F,0xDD,
0x1D,0x1C,0xDC,0x14,0xD4,0xD5,0x15,0xD7,0x17,0x16,0xD6,0xD2,0x12,0x13,0xD3,
0x11,0xD1,0xD0,0x10,0xF0,0x30,0x31,0xF1,0x33,0xF3,0xF2,0x32,0x36,0xF6,0xF7,
0x37,0xF5,0x35,0x34,0xF4,0x3C,0xFC,0xFD,0x3D,0xFF,0x3F,0x3E,0xFE,0xFA,0x3A,
0x3B,0xFB,0x39,0xF9,0xF8,0x38,0x28,0xE8,0xE9,0x29,0xEB,0x2B,0x2A,0xEA,0xEE,
0x2E,0x2F,0xEF,0x2D,0xED,0xEC,0x2C,0xE4,0x24,0x25,0xE5,0x27,0xE7,0xE6,0x26,
0x22,0xE2,0xE3,0x23,0xE1,0x21,0x20,0xE0,0xA0,0x60,0x61,0xA1,0x63,0xA3,0xA2,
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
};


   int8 uchCRCHi, uchCRCLo, uIndex ;
   int16 i ;
  

   uchCRCHi = 0xFF ; 
   uchCRCLo = 0xFF ; 
   
   for(i=0;i < usDataLen ;i++ ) 
   {
      uIndex = uchCRCHi ^ *puchMsg ; 
      
      *puchMsg++ ; 
      
      uchCRCHi = uchCRCLo ^ modbus_CRCHi[uIndex]; 
      uchCRCLo = modbus_CRCLo[uIndex] ;   
   };
   
   i = uchCRCHi ;
   i = (i<<8) | uchCRCLo ; 
   

   return(i); 
   
 
 
   
   
}
//-----------------------------------------------------------
#INT_RDA
void interrupt_rs232(void)
{
   char data ; 
   
   data = getchar(); 
   
   modbus_data_reciever[modbus_index] = data; 
   
   modbus_index++ ; 
   if( modbus_index >= 8 )
   {
      modbus_flag_status = 1; 
      modbus_index = 0; 
      
   };   
   
   //putchar(data); 
   
   
}

còn đây là chương trình