自己用单片机做的Modbus从机，可以使用STC89C52。实现了命令码为1、2、3、4、5、6的功能，程序中有些是我们部分其他功能的函数和数据，希望大家参考下编程的思想。
uint Switch=0xbc95;//开关状态
uchar bdata Coil1=0xff,Coil2=0xbc;//16位线圈状态
sbit Coil1_bit0=Coil1^0;
sbit Coil1_bit1=Coil1^1;
sbit Coil1_bit2=Coil1^2;
sbit Coil1_bit3=Coil1^3;
sbit Coil1_bit4=Coil1^4;
sbit Coil1_bit5=Coil1^5;
sbit Coil1_bit6=Coil1^6;
sbit Coil1_bit7=Coil1^7;
sbit Coil2_bit8=Coil2^0;
sbit Coil2_bit9=Coil2^1;
sbit Coil2_bit10=Coil2^2;
sbit Coil2_bit11=Coil2^3;
sbit Coil2_bit12=Coil2^4;
sbit Coil2_bit13=Coil2^5;
sbit Coil2_bit14=Coil2^6;
sbit Coil2_bit15=Coil2^7;
uint idata
ReOnlybuf[]={0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f};
uint idata
ReWrbuf[]={0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f};
//CRC校验查表码值
const uchar code auchCRCHi[] ={
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};
const uchar code auchCRCLo[] = {
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};
/********************************************
Function：CRC校验子函数
Input:要校验的数组起始地址 长度
Output：16位校验码（高位在前）
********************************************/
uint crccheck(uchar *puchMsg, uchar usDataLen)
{
uchar uchCRCHi = 0xFF ;
uchar uchCRCLo = 0xFF ;
uchar uIndex ;
while (usDataLen--)
{
uIndex = uchCRCHi ^ *puchMsg++ ;
uchCRCHi = uchCRCLo ^ auchCRCHi[uIndex] ;
uchCRCLo = auchCRCLo[uIndex] ;
}
return (uchCRCHi << 8 | uchCRCLo) ;
}
/********************************************
Function：读线圈状态子函数
Input:无
Output：无
********************************************/
void ReadCoil(void)
{
uint StartAddress,tempAddress;
uchar CoilNum,i,ByteNum,j;
uchar CoilVal;
bit exit=0;
StartAddress=resvbuf[2];
StartAddress=StartAddress|resvbuf[3];
tempAddress=StartAddress;
CoilNum=resvbuf[5];//读取的位数
ByteNum=CoilNum/8;
if(CoilNum%8!=0)
ByteNum++;
Sendbuf[2]=ByteNum;//返回的字节数
if(resvbuf[1]==0x01)
{
for(i=0;i Sendbuf[i+3]=0; for(j=0;j<8;j++) { CoilVal=GetCoilVal(StartAddress); Sendbuf[i+3]|=CoilVal< if(StartAddress>=tempAddress+CoilNum) { exit=1; break; } } if(exit==1) break; } } else if(resvbuf[1]==0x02) { for(i=0;i Sendbuf[i+3]=0; for(j=0;j<8;j++) { CoilVal=GetSWVal(StartAddress); Sendbuf[i+3]|=CoilVal< if(StartAddress>=tempAddress+CoilNum) { exit=1; break; } } if(exit==1) break; } } SendCount=5+ByteNum; SendData(); } /******************************************** Function：读寄存器状态子函数 Input:无 Output：无 ********************************************/ void ReadRegisters(void) { uint StartAddress; uchar ByteCount,i; StartAddress=resvbuf[2]; StartAddress=StartAddress<<8|resvbuf[3]; ByteCount=resvbuf[5]*2; Sendbuf[2]=resvbuf[5]; if(resvbuf[1]==0x03) for(i=0;i Sendbuf[i+4]=ReWrbuf[StartAddress]&0xff; Sendbuf[i+3]=ReWrbuf[StartAddress]>>8; StartAddress++; } else if(resvbuf[1]==0x04) for(i=0;i Sendbuf[i+4]=ReOnlybuf[StartAddress]; Sendbuf[i+3]=ReOnlybuf[StartAddress]; StartAddress++; } SendCount=ByteCount+5; SendData(); } /******************************************** Function：强制单线圈子函数 Input:无 Output：无 ********************************************/ void ForceSingalCoil(void) { uint Address,OnOff; bit temp,CoilVal; Address=resvbuf[2]<<8|resvbuf[3]; OnOff=resvbuf[4]<<8|resvbuf[5]; if(OnOff==0x0000) { CoilVal=0; temp=SetCoilVal(Address,CoilVal); } else if(OnOff==0xFF00) { CoilVal=1; temp=SetCoilVal(Address,CoilVal); } if(temp==1) { Sendbuf[2]=resvbuf[2]; Sendbuf[3]=resvbuf[3]; Sendbuf[4]=resvbuf[4]; Sendbuf[5]=resvbuf[5]; SendCount=8; SendData(); } else Error=1; } /******************************************** Function：强制单寄存器子函数 Input:无 Output：无 ********************************************/ void SetOneRegisterVal() { uint R_Address,RegisterVal; bit temp1; R_Address=resvbuf[2]; R_Address=R_Address<<8|resvbuf[3]; RegisterVal=resvbuf[4]; RegisterVal=RegisterVal<<8|resvbuf[5]; temp1=SetRegisterVal(R_Address,RegisterVal); if(temp1==1) { Sendbuf[2]=resvbuf[2]; Sendbuf[3]=resvbuf[3]; Sendbuf[4]=resvbuf[4]; Sendbuf[5]=resvbuf[5]; SendCount=8; SendData(); } else Error=1; } /******************************************** Function：读线圈值子函数 Input:线圈地址 Output：线圈的值 ********************************************/ uchar GetCoilVal(uint Address) { uint CoilAddress; uchar CoilVal=0; CoilAddress=Address; switch(CoilAddress&0x0f) { case 0: CoilVal=Coil1_bit0;break; case 1: CoilVal=Coil1_bit1;break; case 2: CoilVal=Coil1_bit2;break; case 3: CoilVal=Coil1_bit3;break; case 4: CoilVal=Coil1_bit4;break; case 5: CoilVal=Coil1_bit5;break; case 6: CoilVal=Coil1_bit6;break; case 7: CoilVal=Coil1_bit7;break; case 8: CoilVal=Coil2_bit8;break; case 9: CoilVal=Coil2_bit9;break; case 10: CoilVal=Coil2_bit10;break; case 11: CoilVal=Coil2_bit11;break; case 12: CoilVal=Coil2_bit12;break; case 13: CoilVal=Coil2_bit13;break; case 14: CoilVal=Coil2_bit14;break; case 15: CoilVal=Coil2_bit15;break; default: break; } return CoilVal; } /******************************************** Function：读开关值子函数 Input:开关地址 Output：开关值 ********************************************/ uchar GetSWVal(uint Address1) { uchar CoilVal; uchar SW1,SW2=0xff; SW1=P2; Switch=SW2<<8|SW1; switch(Address1&0x0f) { case 0: CoilVal=Switch&0x01;break; case 1: CoilVal=Switch>>1&0x01;break; case 2: CoilVal=Switch>>2&0x01;break; case 3: CoilVal=Switch>>3&0x01;break; case 4: CoilVal=Switch>>4&0x01;break; case 5: CoilVal=Switch>>5&0x01;break; case 6: CoilVal=Switch>>6&0x01;break; case 7: CoilVal=Switch>>7&0x01;break; case 8: CoilVal=Switch>>8&0x01;break; case 9: CoilVal=Switch>>9&0x01;break; case 10: CoilVal=Switch>>10&0x01;break; case 11: CoilVal=Switch>>11&0x01;break; case 12: CoilVal=Switch>>12&0x01;break; case 13: CoilVal=Switch>>13&0x01;break; case 14: CoilVal=Switch>>14&0x01;break; case 15: CoilVal=Switch>>15&0x01;break; default: break; } return CoilVal; } /******************************************** Function：强制单线圈值子函数 Input:线圈地址，强制值 Output：结果值 ********************************************/ bit SetCoilVal(uint Address,bit Val) { bit result=1; switch(Address&0x0f) { case 0: Coil1_bit0=Val;break; case 1: Coil1_bit1=Val;break; case 2: Coil1_bit2=Val;break; case 3: Coil1_bit3=Val;break; case 4: Coil1_bit4=Val;break; case 5: Coil1_bit5=Val;break; case 6: Coil1_bit6=Val;break; case 7: Coil1_bit7=Val;break; case 8: Coil2_bit8=Val;break; case 9: Coil2_bit9=Val;break; case 10: Coil2_bit10=Val;break; case 11: Coil2_bit11=Val;break; case 12: Coil2_bit12=Val;break; case 13: Coil2_bit13=Val;break; case 14: Coil2_bit14=Val;break; case 15: Coil2_bit15=Val;break; default: result=0;break; } P1=Coil1; return result; } /******************************************** Function：设置单寄存器值子函数 Input:寄存器地址，值 Output：结果值 ********************************************/ bit SetRegisterVal(uint Address1,uint Val1) { uchar Addr; bit result1=1; Addr=Address1&0x0f; if(Addr<16) ReWrbuf[Addr]=Val1; else result1=0; return result1; } 因篇幅问题不能全部显示，请点此查看更多更全内容