modbus.c

modbus协议实现

//crc校验值计算
unsigned int cal_crc(unsigned char *ptr, unsigned int len)  
{   
	unsigned int crc=0xffff;   
    unsigned char i;   
    while(len!=0) 
    {   
    	crc^=*ptr; 
        for(i=0;i<8;i++) 
        {   
        	if((crc&0x0001)==0) 
				crc=crc>>1; 
            else  
            { 
              	crc=crc>>1; 
              	crc^=0xa001;  
            }                     
		}  
        len-=1; 
        ptr++;  
	}   
	return crc; 
}   
//---------------------------------------------------------          
void fenli(unsigned int data,unsigned int data1) 
{ 
	send_data[data1]=(unsigned char)(data); 
    send_data[data1+1]=(unsigned char)(data>>8); 
} 
//--------------------------------------------------------- 
unsigned int zhuhe(unsigned char data1,unsigned char data) 
{ 
	unsigned int t; 
    t=data1; 
    t=(t<<8)+data; 
    return t; 
} 
//---------------------------------------------------------    
void send_run(void) 
{ 
	if(send_sp>num_send-1) 
    { 
     	send_sp=0; 
     	flag_send=0; 
    } 
    else 
    { 
     	UDR=send_data[send_sp]; 
     	send_sp++;    
    } 
    num_stop=0; 
} 
//---------------------------------------------------------    
void error(unsigned char data) 
{ 
	unsigned char add; 
    num_send=5; 
    send_data[1]=0x11; 
    send_data[2]=data; 
    add=cal_crc(send_data,3); 
    fenli(add,3); 
} 
//---------------------------------------------------------     
void data_act(void) 
{ 
	unsigned int add,i,n; 
    send_data[0]=address; 
    add=zhuhe(recieve_data[2],recieve_data[3]); 
    add=add*2-2; /*μ??·*/ 
    if(add>49) 
	error(2); 
    else 
    { 
    	if(recieve_data[1]==3) 
      	{ 
      		n=zhuhe(recieve_data[4],recieve_data[5]); /*3¤?è*/    
      		num_send=6+n; 
      		send_data[1]=recieve_data[1];  /*1|?ü*/ 
      		send_data[2]=recieve_data[4]; 
      		send_data[3]=recieve_data[5];  /*3¤?è*/ 
      		for(i=0;i<n;i++) 
      		send_data[i+4]=variable_data[i+add]; 
      		n=4+n; 
      		i=cal_crc(send_data,n); 
      		fenli(i,n); 
     	} 
     	else if(recieve_data[1]==6) 
     	{       
      		num_send=num_recieve; 
      		for(i=1;i<num_recieve;i++) 
      		send_data[1]=recieve_data[1];    
     	} 
     	else error(1); 
     	} 
	} 
//---------------------------------------------------------     
unsigned char crc_recieve(unsigned char data) 
{ 
	unsigned int crc0,crc1; 
    crc0=cal_crc(recieve_data,num_recieve); 
    crc1=zhuhe(recieve_data[data-1],recieve_data[data-2]); 
    if(crc0=crc1) 
		return 1; 
    else 
		return 0; 
} 
//---------------------------------------------------------     
void time1compatt(void)                   
{    
	unsigned char flag; 
    if(flag_send==2) send_run(); 
    num_stop+=1; 
    if(num_stop>3) 
    {          
    	if(flag_send==1) 
      	{  
       		flag=crc_recieve(num_recieve); 
      		if(flag==1) 
      		{ 
       			data_act(); 
       			flag_send=2; 
       			num_recieve=0; 
      		} 
      	} 
     	num_stop=0;                  
     } 
} 
//---------------------------------------------------------     
#pragma interrupt_handler usrt_resieve:12     
void usrt_resieve(void)                   
{    
	recieve_data[num_recieve]=UDR; 
    num_recieve+=1; 
    num_stop=0; 
    flag_send=1; 
}  
//---------------------------------------------------------