我做过modbus-rtuMAX485通讯，参考的“一线工人”
/*********************************************
**项目:开关量数据采集(EE01学习板演示程序)
**作者：一线工人
**网站：电子工程师之家 www.eehome.cn
**备注：modbus协议，rs485通讯
刚刚写完了的rs485通讯程序
测试截图
Labview写的专用测试程序截图
*********************************************/
#include<reg52.h>
//#include<main.h>
#define uchar unsigned char
#define uint unsigned int
sbit rx_led=P0^0;//接收指示灯
sbit tx_led=P0^1;//发送指示灯
sbit ctrl_485=P3^2;//485接发发送转换控制
sbit dm=P1^4;
sbit wm=P1^5;
sbit led_cs=P1^6;
sbit b7=P2^7;//波特率设置位
unsigned int crc=0;
uchar sendBuf[20],a[10];
uchar send_count= 0,send_num=0,addr_dip=0;
uchar receive_count=0;//定义变量并赋予0 接收数组计数器
uchar mysend[6],aq[8];//定义数组
uint crc16(unsigned char *puchMsg, unsigned int usDataLen);
void beginsend(void);
void check_modbus(void);
/*************延时*****************/
void delay(uint z)
{
uint y;
while(z--)
for(y=113;y>0;y--);
//uint x,y;
//for(x=z;x>0;x--)
//for(y=113;y>0;y--);
}
/************串口初始化*****************/
void uart_init(void)
{
TMOD=0x20;//定时器1，模式2
SCON=0x50;//串口通讯方式1
TH1=0xfd;//波特率9600
TL1=0xfd;
if(b7==1)PCON=0x00; else PCON=0x80;
TI=0;//发送中断标志位清零
RI=0;//接收中断标志位清零
TR1=1;//启动定时器1
EA=1;
ES=1;
}
/**************定时器0初始化**************/
void timer0_init(void)
{
TMOD=TMOD&0xf0;
TMOD=TMOD|0x01;
TH0=0;
TL0=0;
ET0=1; //允许定时器中断
}
void main(void)
{
dm=0;
wm=0;
led_cs=1;
uart_init();
timer0_init();
ctrl_485=0;//先置为接收
while(1)
{
RI=0;
delay(1);
rx_led=1;
tx_led=1;
}
}
void beginsend(void)
{
ctrl_485=1;
TI=0;
send_count = 0;
SBUF = sendBuf[0];
send_num--;
}
void time0() interrupt 1///定时器中断
{
TR0=0;
RI=0;
check_modbus();
receive_count=0;
}
void ser() interrupt 4
{
if(TI)
{
if(send_count < send_num)
{
TI=0;
tx_led=0;
SBUF = sendBuf[++send_count];
}
else
{
receive_count=0;
ctrl_485=0;
TI=0;
}
}
else
if(RI)
{
RI=0;
rx_led=0;
TR0=1;
a[receive_count++]=SBUF;
TH0=0xf4;
TL0=0x1e;
}
}
void check_modbus(void)
{
uchar di,addr;
if(receive_count>7)////////////////////address 03 00 00 00 01 crc crc
{
//CRC检验函数
receive_count=0;
crc=crc16(a,6);
addr=P2>>4;
addr=~(addr&0x0f);
addr=addr&0x0f;
di=~(P2&0X0f);
di=di&0x0f;
if(a[0]==addr&&a[1]==0x03&&(crc==((a[7]&0x00ff)|(0xff00&(a[6]<<8)))))
{
//发送函数
sendBuf[0]=a[0];
sendBuf[1]=a[1];
sendBuf[2]=0x02;
sendBuf[3]=0x00;
sendBuf[4]=di;
crc=crc16(sendBuf,5);
sendBuf[5]=crc>>8;
sendBuf[6]=crc&0xff;
send_num=7;
beginsend();
}
}
}
/***********************CRC校验*************************/
// CRC 高位字节值表
unsigned char code auchCRCHi[260] = {
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
} ;
// CRC低位字节值表
unsigned char code auchCRCLo[260] = {
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
} ;
//CRC校验程序
unsigned int crc16(unsigned char *puchMsg, unsigned int usDataLen)
{
unsigned char uchCRCHi = 0xFF ; //* 高CRC字节初始化
unsigned char uchCRCLo = 0xFF ; //* 低CRC 字节初始化
unsigned long uIndex ; // CRC循环中的索引
while (usDataLen--) // 传输消息缓冲区
{
uIndex = uchCRCHi ^ *puchMsg++ ; // 计算CRC
uchCRCHi = uchCRCLo ^ auchCRCHi[uIndex] ;
uchCRCLo = auchCRCLo[uIndex] ;
}
return (uchCRCHi << 8 | uchCRCLo);
}
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