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Unable to read data from Serial port
I am new to the linux.I have written a program in c/C++ to communicate with a device through serial port.This program is not able to read data from serial port.
I tried to connect the device using minicom and it seems to working fine.
Here is the program:-
#include <stdio.h>
#include <iostream>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>
#include <unistd.h>
#include <string.h>
using namespace std;
int fd1;
int fd2;
string string_f;
//char *buff,*buffer,*bufptr;
char *buff;
int wr,rd,nbytes,tries;
const int MAXDATASIZE = 512;
// std::vector<char> m_vRequestBuf;
char buffer[MAXDATASIZE];
int totalBytes = 0;
//struct termios port_settings;
int configure_port(int fd);
int main()
{
fd1=open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY);
if (fd1 == -1 )
{
perror("open_port: Unable to open /dev/ttyS0 – ");
}
else
{
fcntl(fd1, F_SETFL,0);
printf("Port 1 has been successfully opened and %d is the file description\n",fd1);
fd1 = configure_port(fd1);
printf("Port Configured \n");// apply the settings to the port
}
printf("Start Writing... \n");
wr = write(fd1,"SFC\r",4);
if (wr < 0)
printf("no bytes written \n");
else
printf("bytes written %d \n" ,wr );
fcntl(fd1, F_SETFL, FNDELAY);
for(int i=0;i<10;i++)
{
rd=read(fd1,buffer,MAXDATASIZE);
if(rd > 0)
{
string_f+= buffer;
cout << "charsRead" << rd << endl;
//Sleep for some time and read again
}
usleep(100);
}
close(fd1);
return 0;
}
int configure_port(int fd) // configure the port
{
struct termios port_settings; // structure to store the port settings in
tcgetattr(fd, &port_settings);
cfsetispeed(&port_settings, B9600); // set baud rates
cfsetospeed(&port_settings, B9600);
port_settings.c_cflag &= ~PARENB; // set no parity, stop bits, data bits
port_settings.c_cflag &= ~CSTOPB;
port_settings.c_cflag &= ~CSIZE;
port_settings.c_cflag |= CS8;
port_settings.c_cflag &= ~CRTSCTS;
port_settings.c_cflag |= (CLOCAL | CREAD);
tcflush(fd, TCIFLUSH);
tcsetattr(fd, TCSANOW, &port_settings);
return(fd);
} //configure_port
Last edited by tanu1985; 10-12-2011 at 04:30 PM.
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