Strange!! I am able to run the same program (I used /dev/ttyS1, since I
don't have /dev/ttyS2) successfully on my machine.
Regards
Mohanlal
----- Original Message -----
From: <Raja.Hayek@xxxxxxxxxxxxxx>
To: <kernelnewbies@xxxxxxxxxxxx>
Sent: Thursday, July 29, 2004 3:02 AM
Subject: Writing to /dev/ttyS
> I am trying to write data through a serial com port, but continuously get
> an error returned by the function call. Basically, my code is simple and
> looks like this:
>
> // includes go here
> int main()
> {
> int res, fd1;
> char buf1[255];
>
> fd1 = open("/dev/ttyS2", O_RDWR| O_NOCTTY | O_NDELAY);
>
> printf("fd1 = %d\n", fd1);
>
> // prepare outgoing message
> sprintf(buf1, "this is a test", sizeof("this is a test"));
>
> res = write(fd1, buf1, strlen(buf1));
> printf("res = %d, errno = %d\n", res, errno);
>
> return 0;
> }
>
> When I run the program, res comes up as -1 and errno as 9 (EBADF). When I
> checked the value of this EBADF, it turned out to be "fd is not a valid
> file descriptor or is not open for writing".
> This is the output I get:
> fd1 = 3
> buf1 : this is a test
> res = -1, errno = 9
>
>
> Although here is what I get when I check the settings of that port with
> setserial:
>
> # setserial -g /dev/ttyS2
> /dev/ttyS2, UART: 16650, Port: 0x03e8, IRQ: 4
>
> which appears to be OK, plus the fact that the open() command returned a
> value of 3 for the file descriptor.
>
> TIA.
>
>
--
Kernelnewbies: Help each other learn about the Linux kernel.
Archive: http://mail.nl.linux.org/kernelnewbies/
FAQ: http://kernelnewbies.org/faq/
