51单片机modbus实例

【实例截图】

【核心代码】

#include "main.h"

/******************************
微控电子 www.mcuc.cn
modbus RTU 的C51程序 
单片机89S52
通信波特率 9600 8位数据 1位停止位 偶校验 485通位接口
单片机控制板地址 localAddr(变量)
通信可设置数据的地址：
字地址 0 - 255 (只取16位的低8位)
位地址 0 - 255 (只取16位的低8位)
*******************************/

uint32	dwTickCount,dwIntTick;	//时钟
uint8	idata sendBuf[16],receBuf[16]; //发送接收缓冲区
uint8	idata checkoutError;	// ==2 偶校验错  
uint8	idata receTimeOut;		//接收超时
uint8	idata c10ms;			//10ms 计时
bit		b1ms,bt1ms,b10ms,bt10ms,b100ms,bt100ms;	//定时标志位

// 串行中断程序
void commIntProc() interrupt 4
{
	if(TI)
	{
		TI = 0; 
		if(sendPosi < sendCount) 
		{
			sendPosi  ;
			ACC = sendBuf[sendPosi];
			TB8 = P;	//加上校验位
			SBUF = sendBuf[sendPosi];
		}
		else
		{
			b485Send = 0;    //发送完后将485置于接收状态
			receCount = 0;   //清接收地址偏移寄存器
			checkoutError = 0;
		}
	}
	else if(RI)
	{
		RI = 0;
		receTimeOut = 10;    //通讯超时值
		receBuf[receCount] = SBUF;
		ACC = receBuf[receCount];
		if(P != RB8)
			checkoutError = 2;	//偶校验出错
		receCount  ;          //接收地址偏移寄存器加1
		receCount &= 0x0f;    //最多一次只能接收16个字节
	}

}   // void CommIntProc()

//定时器0 1ms 中断
void timer0IntProc() interrupt 1
{
	TL0 = TIMER_LOW; 
    TH0 = TIMER_HIGHT;
    dwIntTick  ;
	bt1ms = 1;
    c10ms  ;
    if(c10ms >= 10) 
    {
        c10ms = 0;      //10ms计时器清零
        bt10ms = 1;
    }
}   // void Timer0IntProc()

//外部中断0
void intEx0Proc(void) interrupt 0
{

}

//计数器1中断
void counter1IntProc(void) interrupt 3 using 1
{

}


//定时处理
void timeProc(void)
{
	static uint8 c200ms;

    bWatchDog = ~ bWatchDog;    //看门狗取反
	b1ms = 0;
	b10ms = 0;
	b100ms = 0;
	
	ET0 = 0;
	dwTickCount = dwIntTick;
	ET0 = 1;

	if(bt1ms)
	{
		bt1ms = 0;
		b1ms = 1;

        if(receTimeOut>0)
        {
            receTimeOut--;
            if(receTimeOut==0 && receCount>0)   //判断通讯接收是否超时
            {
                b485Send = 0;       //将485置为接收状态
                receCount = 0;      //将接收地址偏移寄存器清零
				checkoutError = 0;
            }
        }
	}
	
	if(bt100ms)
	{
		bt100ms = 0;
		b100ms = 1;
	}
    if(bt10ms)      //判断中断10ms标志位是否1
    {
        bt10ms = 0;     //清中断10ms标志位
		b10ms = 1;

        c200ms  ;                   //200ms计时器加1
        if(c200ms >= 20)            //判断是否计时到200ms
        {
            c200ms = 0;             //清200ms计时器
            bRunLED = ~bRunLED;     //取反运行指示灯          
        }
    }
}   // void TimerProc(void)

//初始化串口
void initUart(void)
{
	//T2 用于波特率 9600
	T2CON = 0x30;
	RCAP2H = 0xff;
	RCAP2L = 0xb8;
	TR2 = 1;

	//偶校验 						
	SCON = 0xd0;
    PCON = 0;
    ES = 1;
}//void initUart(void)

//初始化中断
void initInt(void)
{
	TMOD = 0x51;
	TH0 = TIMER_HIGHT;
	TL0 = TIMER_LOW;
	TR0 = 1;	
    ET0 = 1;
	TH1 = 0;			//9600
    TL1 = 0;
	TR1 = 0;			//定时器1用于计数定时器2用于波特
	ET1 = 1;
	//PT1 = 1;

	IT0 = 1;	
    IT1 = 1;
	EX0 = 0;	
	PX0 = 1;
    EX1 = 0;

	initUart();

	EA = 1;		
}   // void initInt(void)

//初始化
void initProg(void)
{	
	initInt();
	b485Send = 0;
}

void main(void)
{
	initProg();

	while(1)
	{
		timeProc();
		checkComm0Modbus();
	}
}