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From: rkwee@ee.pdx.edu (Roland Kwee)
Newsgroups: comp.os.386bsd.questions
Subject: Serial port blocks on CARRIER
Date: 4 Jan 1995 00:56:05 -0800
Lines: 21
Message-ID: <3ednr5$nm7@cruella.ee.pdx.edu>
NNTP-Posting-Host: cruella.ee.pdx.edu
Summary: How to get the serial port to NOT block on the CARRIER line?
Keywords: serial blocking cd stty ioctl handshake
X-Newsreader: NN version 6.4.19 #2
On my FreeBSD 1.0 system, I am having a problem with using the
serial port carrier signal. On startup, it is in mode -clocal.
Before dialing out, the modem has the CARRIER signal on False,
but this makes the port 'hang'. Even 'stty' hangs when I try
to set clocal. With the program fragment below, I finally had
a way to set the port to clocal:
fd=open(argv[1], O_RDWR|O_NONBLOCK);
tcgetattr(fd, &tbuf);
tbuf.c_cflag |= CLOCAL;
tcsetattr(fd, TCSANOW, &tbuf);
Note the flags O_NONBLOCK and TCSANOW.
Question: Is this really the best way to do it? Is there no
way to run stty in non-blocking mode?
Thanks for any help.
--Roland Kwee email: rolandkwee@acm.org