Date: Tue, 10 Dec 1996 22:57:57 -0700 (MST) From: Brandon Gillespie <brandon@glacier.cold.org> To: Mark Taylor <mtaylor@cybernet.com> Cc: hackers@freebsd.org Subject: RE: Help! Turning off DTR on a serial device Message-ID: <Pine.NEB.3.95.961210225420.10600A-100000@glacier.cold.org> In-Reply-To: <XFMail.961205172226.mtaylor@cybernet.com>
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On Fri, 6 Dec 1996, Mark Taylor wrote: > On 18:25:06 Brandon Gillespie wrote: > >I'm writing some software to use the serial device in FreeBSD (and > >Unixware in the long run). I need to know if I can turn off DTR. The > >supplied software with this program is for DOS, and manages to turn off > >DTR from the software end--but I have never been able to figure out if I > >can do this from a unix perspective? Can I? help? > > > >-Brandon Gillespie > > There is an IOCTL for it. > Look in /usr/include/sys/ttycom.h for TIOCSDTR (set DTR) and TIOCCDTR (clear > DTR). > > The only problem youu will find with it is that the DTR is set when you change > your > baud rate. There is an 'if' statement in the baud changing code in the > kernel's sio > driver which checks if the baud is non-zero, then the DTR will be set. > > So, you can set your baud rate, turn off your DTR, but don't chang your baud > rate > again! It will turn ON the DTR (if the new baud rate is not zero). How portable is this? I'm developing the software in FreeBSD but it will be running on a Unixware server. Anybody familiar with unixware? -Brandon Gillespie
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