I get EAGAIN Error

[validator]

I use serial port. I get serial EAGAIN error. I open serial port with below settings.

do I have any error with settings.

Thanks.



static int fd=-1;

bool openPort(int baudrate, const char * ThePort) {

unsigned long BAUD;
struct termios port_settings;
fd = open(ThePort, O_RDWR | O_NOCTTY | O_NDELAY );

tcgetattr(fd, &port_settings);

if (fd == -1) // if open is unsucessful
{
//perror("open_port: Unable to open /dev/ttyS0 - ");
printf("open_port: Unable to open /dev/tty0. \n");
} else {

fcntl(fd, F_SETFL, FNDELAY);
printf("port is open.\n");
}

switch (baudrate) {
case 115200:
BAUD = B115200;
break;
case 57600:
BAUD = B57600;
break;
case 38400:
BAUD = B38400;
break;
case 9600:
BAUD = B9600;
break;
default:
BAUD = B38400;
break;
}

// structure to store the port settings in

cfsetispeed(&port_settings, BAUD); // set baud rates
cfsetospeed(&port_settings, BAUD);




port_settings.c_cc[VMIN] = 1;
port_settings.c_cc[VTIME] = 0;


port_settings.c_iflag = IGNPAR | IUCLC;
port_settings.c_oflag = 0;
port_settings.c_lflag = 0;
port_settings.c_cflag |= (CLOCAL | CREAD);
port_settings.c_cflag &= ~(CSIZE | PARENB);
port_settings.c_cflag &= ~CSTOPB;
port_settings.c_cflag |= CS8;

tcsetattr(fd, TCSANOW, &port_settings); // apply the settings to the port
return (fd);

}

[Rubberman]

Please show the code where you are getting the EAGAIN error. What it means depends upon the context you are in at the time and what you are doing. For example, in a read() operation it means that the socket/port was in a non-blocking state and that there was no data available to read. In such a case, it isn't an error as such, but more of an advisory.

[Schmidt]

In common sense EAGAIN means that kernel tells you "Hey, dude, there's nothing to do, try again later!" I suggest you try to read from a port and nothing writing data to it at the moment.

[validator]

Please show the code where you are getting the EAGAIN error. What it means depends upon the context you are in at the time and what you are doing. For example, in a read() operation it means that the socket/port was in a non-blocking state and that there was no data available to read. In such a case, it isn't an error as such, but more of an advisory.

I get this error in below code


for (index = 0;; index++) {

int iIn = read(fd, buffer + index, 1);

//buffer[iIn-1] = 0x00;

if (iIn < 0) {
if (errno == EAGAIN) {
printf("SERIAL EAGAIN ERROR\n"); /
return 0;
} else {
printf("SERIAL read error %d %s\n", errno, strerror(errno));
return 0;
}
}
}