Serial Port Access Denied using open("/dev/ttyS0", O_RDWR | O_NOCTTY

morty346 · 02-10-2009, 10:43 AM

I am creating a program that opens a serial port for communication but it gets denied when I open it
I have installed a board that has two ports and have verified they are working by using the terminal:
dmesg | grep tty
console [tty0] enabled
0000:02:00.0: ttyS0 at I/O 0xdf00 (irq = 21) is a 16550A
0000:02:00.0: ttyS1 at I/O 0xde00 (irq = 21) is a 16550A

Code:

Code:

 int open_port(void)
    {
      int fd; /* File descriptor for the port */


      fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY);
      if (fd == -1)
      {
       /*
	* Could not open the port.
	*/
	perror("open_port: Unable to open /dev/ttyS0 - ");
      }
      else
	fcntl(fd, F_SETFL, 0);

      return (fd);
    }

open_port: Unable to open /dev/ttyS0 -: Permission denied
return code -1

Thank you
Greg

morty346 · 02-10-2009, 11:02 AM

Solved!

chmod o+rw /dev/ttyS0
chmod o+rw /dev/ttyS1

Thank you anyways!
Greg

02-10-2009, 10:43 AM	#1
morty346 Registered User Join Date: Feb 2009 Posts: 3	Serial Port Access Denied using open("/dev/ttyS0", O_RDWR \| O_NOCTTY \| O_NDELAY); I am creating a program that opens a serial port for communication but it gets denied when I open it I have installed a board that has two ports and have verified they are working by using the terminal: dmesg \| grep tty console [tty0] enabled 0000:02:00.0: ttyS0 at I/O 0xdf00 (irq = 21) is a 16550A 0000:02:00.0: ttyS1 at I/O 0xde00 (irq = 21) is a 16550A Code: Code: int open_port(void) { int fd; /* File descriptor for the port / fd = open("/dev/ttyS0", O_RDWR \| O_NOCTTY \| O_NDELAY); if (fd == -1) { / * Could not open the port. */ perror("open_port: Unable to open /dev/ttyS0 - "); } else fcntl(fd, F_SETFL, 0); return (fd); } open_port: Unable to open /dev/ttyS0 -: Permission denied return code -1 Thank you Greg
morty346 is offline

02-10-2009, 11:02 AM	#2
morty346 Registered User Join Date: Feb 2009 Posts: 3	Solved! chmod o+rw /dev/ttyS0 chmod o+rw /dev/ttyS1 Thank you anyways! Greg
morty346 is offline

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