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Article #1159

Re: Forcing DTR low on modem to hangup from Linux?

#1159
From: Al Longyear
Date: Wed, 20 Jul 1994 15:05
27 lines
2074 bytes
jrmt@froggy.demon.co.uk (Jon Thackray) writes:

>I've been trying to get a 'hangup' program to run after PPP terminates,
>to hang up the modem. SLIP (via the DIP program) use the '+++' and 'ATH'
>commands, but these don't seem to work if the modem is busy receiving data.
>(I think the manual says that '+++' needs a 1 second gap)

>What's the best way to force DTR low (it is DTR, isn't it?), so that the
>modem is /guaranteed/ to go offline ...? Would I need to add a call to the
>kernel to be able to do this, or could it be done from user mode?

If you specify that you have a "modem" connection (with the modem
parameter), the pppd process will enable the HUPCL parameter for the
serial device.

This seems to work for most people in that when the last opener closes the
serial device, the "Hang UP" sequence is performed by the serial.c code in
the kernel by dropping the DTR signal.

Do you have any other openers on the serial device? This will only work if
pppd is the only process to have the serial device open.

There is a "disconnect" parameter which may be used, similar to the "connect"
parameter, to run a program to disconnect the link.

-- 
Al Longyear           longyear@netcom.com
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From: longyear@netcom.com (Al Longyear)
Subject: Re: Forcing DTR low on modem to hangup from Linux?
Message-ID: <longyearCt8v9v.5ps@netcom.com>
Organization: NETCOM On-line Communication Services (408 261-4700 guest)
References: <30hcgo$rc@froggy.demon.co.uk>
Date: Wed, 20 Jul 1994 15:05:54 GMT
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