Date: Tue, 9 Jul 1996 16:18:35 -0500 (CDT) From: bugs@freebsd.netcom.com (Mark Hittinger) To: questions@freebsd.org Subject: Re: forcing a modem to hangup (fwd) Message-ID: <199607092118.QAA24002@freebsd.netcom.com>
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>terry@lambert.org writes: > The default POST setting for DTR should be such that it is *not* asserted > unless it has been specifically asserted. > > An on-to-off transition of DTR will cause your modem to reset as if > powered off then on. > > Failure modes: > > 1) Internal modems. Don't buy them, you can't trust them. > 2) Modem not set to follow DTR correctly. Modem should reset > as if powered off then back on on on-to-off DTR transition; > if your modem does not do this, it is set up incorrectly. > 3) Modem does not signal DCD loss to computer. Modem should > on-to-off transition DCD signal when remote carrier is lost. Another weird failure mode is that the dtr signal is not dropped for long enough for your modem - you might see this on a faster box. I remember having to patch the getty on Xenix to sleep an additional second before opening the terminal device - this forced dtr down at least a second and allowed the required hangup. Regards, Mark Hittinger Netcom/Dallas bugs@freebsd.netcom.com
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