Path: utzoo!utgpu!cunews!bnrgate!brtph3!brchh104!brchs1!bnr.ca!rice.edu!sun-spots-request
From: wor-mein!dave@uunet.uu.net (Dave Axness)
Newsgroups: comp.sys.sun
Subject: Need help reading RS-232 control signals
Keywords: Hardware
Message-ID: <700@brchh104.bnr.ca>
Date: 8 Dec 90 22:07:00 GMT
Sender: news@brchh104.bnr.ca
Organization: Sun-Spots
Lines: 28
Approved: Sun-Spots@rice.edu
X-Original-Date: Tue, 4 Dec 90 09:20:28 pst
X-Sun-Spots-Digest: Volume 9, Issue 395, message 9
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I recently installed an uninterruptable power supply that has an RS-232
interface.  Several pins on RS-232 connector are assigned to indicate the
status of the UPS ( ex. AC power fail, battery low, etc. ).  I'm trying to
write a program to monitor this so that I can force an automatic shutdown
when the battery starts to run out.

It seems like I should be able to use ioctl to accomplish this but have
had no luck so far.  I'm using the ttya port on the back of a 3/60.  I'm
still running SUNOS 3.5 if that's an issue.  Here's a code fragment:

	int   tty_status
	FILE *ip;

	ip = fopen("/dev/ttya","rw");

	ioctl ( ip, TIOCMODG, &tty_status );

	printf ("ttys status = 0x%x\n", tty_status );

I've tried to change the state of pin 20 (DTR) be connecting it to pin 7
(GND) or pin 25 (-5V) but the value of tty_status is always 0.  Am I
trying to do this the right way or am I missing something here.  Any help
would be appreciated.

Dave Axness
Quantum Medical Systems, Inc.
Issaquah, WA
uunet!wor-mein!dave