Help about serial programming: manipulating DTR

Corinna Vinschen
Wed Feb 2 18:13:00 GMT 2005

On Feb  2 17:34, llandre wrote:
> Hi all,
> I'm trying to manipulate the DTR signal of the serial port.
> As an example I used this code snippet: 
> I can open the com1, I can send and receive data but the ioctl I use
> to read the status of the signals returns -1:
>     int status;
>     ioctl(upsfd, TIOCMGET, &status);
> Anybody can help me? I have no idea about what's wrong with this code.

strace would give a hint.  TIOCMGET should only fail because a call to
GetCommModemStatus fails.  If so, the strace would contain a line which
talks about setting errno in fhandler_serial::ioctl.


Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader
Red Hat, Inc.

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