Modem control on ttyS0

[Bill Campbell]

On Mon, Jul 29, 2002 at 03:19:20PM -0500, Michael Hipp wrote:
>How do I enable modem control on the ttyS0 serial port?
>
>I'm trying to get a APC UPS to work with basic signaling and it keeps
>complaining that I need modem control enabled.

Are you using the correct cable?  The APC SmartUPS come with two cables,
grey and black.  The black cable is used with proper modem control.  Unlike
SCO OpenServer which has different devices for modem control and no modem
control, Linux generally only as one.

Is it possible that you have some other device that has the modem port
open?  ``lsof /dev/ttyS0'' should tell you what processes are using it if
this is the problem.

Bill
--
INTERNET:   bill at Celestial.COM  Bill Campbell; Celestial Systems, Inc.
UUCP:               camco!bill  PO Box 820; 6641 E. Mercer Way
FAX:            (206) 232-9186  Mercer Island, WA 98040-0820; (206) 236-1676
URL: http://www.celestial.com/

``A Democracy cannot exist as a permanent form of government.  It can only
exist until the voters discover they can vote themselves largesse out of
the public treasury.  From the moment on the majority always votes for the
candidate promising the most benefits from the public treasury with the
result that Democracy always collapses over a loose fiscal policy, always
to be followed by a Dictatorship.''
	Professor Alexander Fraser Tytler.  Date unknown.