232_485.c

通过485读取国标电表的有功电量

#include <reg51.h>
#include <string.h>

#define INBUF_LEN 40 //数据长度

#define TR_485_OUT P1 |= 0x10 //TR_485 = 1
#define TR_485_IN P1 &= 0xef //TR_485 = 0
#define WK_1 P1 |= 0x20 //WK = 1
#define WK_0 P1 &= 0xdf //WK = 0
#define ON_485 P1 &= 0xbf //
#define OFF_485 P1 |= 0x40 //
#define ON_232 P1 |= 0x80
#define OFF_232 P1 &= 0x7f

unsigned char inbuf1[INBUF_LEN];
unsigned char checksum,count3;
bit read_flag= 0 ;


void init_serialcomm( void )
{
	SCON = 0x50 ; //SCON: serail mode 1, 8-bit UART, enable ucvr
	TMOD |= 0x20 ; //TMOD: timer 1, mode 2, 8-bit reload
	PCON |= 0x80 ; //SMOD=1;
	TH1 = 0xF4 ; //Baud:4800 fosc=11.0592MHz
	IE |= 0x90 ; //Enable Serial Interrupt
	TR1 = 1 ; // timer 1 run
	// TI=1;
}

//向串口发送一个字符
void send_char_com( unsigned char ch)
{
	SBUF=ch;
	while (TI== 0 );
	TI= 0 ;
}

//向串口发送一个字符串，strlen为该字符串长度
void send_string_com( unsigned char *str, unsigned int strlen)
{
	unsigned int k= 0 ;
	do
	{
		send_char_com(*(str + k));
		k++;
	} while (k < strlen);
}


//串口接收中断函数
void serial () interrupt 4 using 3
{
	if (RI)
	{
		unsigned char ch;
		RI = 0 ;
		ch=SBUF;
		if (ch> 127 )
		{
			count3= 0 ;
			inbuf1[count3]=ch;
			checksum= ch- 128 ;
		}
		else
		{
			count3++;
			inbuf1[count3]=ch;
			checksum ^= ch;
			if ( (count3==(INBUF_LEN- 1 )) && (!checksum) )
			{
				read_flag= 1 ; //如果串口接收的数据达到INBUF_LEN个，且校验没错，
				//就置位取数标志
			}
		}
	}
}


main()
{
        P1 = 0;
        TR_485_OUT ;
        TR_485_IN;
        WK_1;
        WK_0;
        ON_485;
        OFF_485;
        ON_232;
        OFF_232;
        init_serialcomm(); //初始化串口
	while ( 1 )
	{
		if (read_flag) //如果取数标志已置位，就将读到的数从串口发出
		{
			read_flag= 0 ; //取数标志清0
			send_string_com(inbuf1,INBUF_LEN);
		}
	}

}