Linux Serial port setting for turning DTR off

[kardon33]

Hello Bytes,

I am writing a program in Linux Debian x86 to control a module.

My only problem is that the module needs to have the DTR setting and all flow control off. I have been unable to figure out how to do this.

This is how ive configured my port settings thus far:

Any ideas??

     fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY);

    if ( fd == -1) // if open is unsucessful
    {
        perror("open_port: Unable to open /dev/ttyUSB0 - ");
    } else {
        fcntl( fd, F_SETFL, 0);
    }

    struct termios port_settings; // structure to store the port settings in

    cfsetispeed(&port_settings, B57600); // set baud rates
    cfsetospeed(&port_settings, B57600);

    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;

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

[Oralloy]

I think you want the function ioctl().

[kardon33]

This is what ive come up with.

After I do my port setting i use ioctl():

    //status &= ~TIOCM_DTR;
    //status &= ~TIOCM_CTS;

    status |= TIOCM_DTR;
    status |= TIOCM_CTS;

    ioctl(fd, TIOCMSET, &status);

Neither low or high bit status for TIOCM_DTR seems to work though?

Is this the right way?

[Oralloy]

@kardon33,

You might need to look on the Debian site. Here are three good references for ioctl:

http://linux.die.net/man/2/ioctl

http://linux.die.net/man/2/ioctl_list

And here is the ioctl tty driver reference from the same site:

http://linux.die.net/man/4/tty_ioctl

I'm pretty sure the last one is what you need.