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To: freebsd-questions@freefall.cdrom.com
Subject: Serial port handling in 2.0.5R?
Date: Sun, 18 Jun 1995 14:59:29 -0700
From: Darryl Okahata <darrylo@hpnmhjw.sr.hp.com>
Sender: questions-owner@FreeBSD.org
Precedence: bulk

Hi,

     Did the serial port flow control handling change between 1.1.5.1
and 2.0.5R?  I just upgraded from 1.1.5.1 to 2.0.5R, and I'm sorely
confused as to how outgoing flow control is handled when trying to call
out.  The problem that I'm seeing is that the carrier detect line is
controlling output flow if crtscts is set.

     Basically, with this condition on my outgoing device, /dev/cuaa1:

	clocal crtscts -mdmbuf etc.

I cannot make an outgoing call, because the sio driver will not send
characters to the modem because the modem does not have the carrier
detect line asserted.  If I futz with the modem to force the carrier
detect line to be always on, I can then make outgoing calls (this is, of
course, a problem is I ever want to accept incoming calls).  Another
"workaround" that I've found is to disable crtscts, e.g.:

	clocal -crtscts -mdmbuf etc.

However, I want hardware flow control (compounding the problem is that
cu always seems to set crtscts, even though it's not set in
/dev/cuaia1).

     I this a bug, or am I just not using the port correctly?

     Thanks,

     -- Darryl Okahata
	Internet: darrylo@sr.hp.com

DISCLAIMER: this message is the author's personal opinion and does not
constitute the support, opinion or policy of Hewlett-Packard or of the
little green men that have been following him all day.