Forcing DTR low on modem to hangup from Linux?

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3 total messages Started by Jon Thackray Tue, 19 Jul 1994 20:25

#1157

Author: Jon Thackray
Date: Tue, 19 Jul 1994 20:25

13 lines
1546 bytes

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?

Cheers,
Jon.
-- 
// Jon Thackray, 18 Windmill Wood, Amersham, Bucks. (0494) 721234.

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

#1158

Author: Rob Janssen
Date: Wed, 20 Jul 1994 07:55

20 lines
1800 bytes

In <30hcgo$rc@froggy.demon.co.uk> 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?

Normally, just closing the port should do that.
When it doesn't, make sure the HUPCL bit is set in the termios structure.

Rob
-- 
-------------------------------------------------------------------------
| Rob Janssen                | AMPRnet:   rob@pe1chl.ampr.org           |
| e-mail: pe1chl@rabo.nl     | AX.25 BBS: PE1CHL@PI8UTR.#UTR.NLD.EU     |
-------------------------------------------------------------------------

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

#1159

Author: 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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