Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!rutgers!mtune!jhc From: jhc@mtune.ATT.COM (Jonathan Clark) Newsgroups: comp.sys.att Subject: Re: How do you get the 3B1 serial port to respond to BREAK? Message-ID: <1153@mtune.ATT.COM> Date: Thu, 20-Aug-87 18:48:37 EDT Article-I.D.: mtune.1153 Posted: Thu Aug 20 18:48:37 1987 Date-Received: Sat, 22-Aug-87 12:32:30 EDT References: <232@amanue.UUCP> Reply-To: jhc@mtune.UUCP (Jonathan Clark) Organization: AT&T ISL Middletown NJ USA Lines: 60 Keywords: BREAK getty change baud rate Summary: Works fine for me. In article <232@amanue.UUCP> jr@amanue.UUCP (Jim Rosenberg) writes: >OK, I give up. How do you get a getty on /dev/tty000 to change the baud rate >in response to a BREAK? You probably did this already, but in /etc/gettydefs put: 1200 # B1200 HUPCL # B1200 HUPCL SANE TAB3 # login: # 2400 2400 # B2400 HUPCL # B2400 HUPCL SANE TAB3 # login: # 1200 Connect to the port at 2400, send a BREAK, and away you go. Running '/etc/getty -c /etc/gettydefs' may prove helpful. I suspect that your PC terminal emulators are actually not sending a real BREAK (0 bits for 1/2 a second, close enough). The key is in the following sentence: >The same L.sys entry expect-send sequences *do work* when I uucp to maxepr, >which has a 2400 baud modem starting off at 1200 on an *expansion port*. Now I *know* that the s4's tty driver sends a real BREAK. I also have a few hundred s4's around here which switch speeds quite happily. On all their ports, before you cavil. >On many machines, including my VENIX machine, there is a way to tell the driver >to ignore hardware handshake lines, like the dip-switch settings on most >modems. The 3B1 doesn't seem to have this. It's called CLOCAL. >Are you supposed to go completely >through the termio(7) struct to enable and disable modem control? Sure, this isn't BSD you know. You could always use stty(1). >ATE has a >form somewhere talking about modem control. Anybody know how ATE does it? via CLOCAL. Backwards. The stock tty driver defaults to CLOCAL *set*, and fooling with this option in the ATE *unsets* it. Various of the HFC drivers start out with CLOCAL *unset* like the manual says. 3.51 has it set because the printer software breaks without this. >On my VENIX machine I have a script that will disable the getty and tell the >line to ignore the fact that it hasn't got carrier detect. This lets me >call out under control of shell scripts, then bring back the getty when the >call is done. I'm not sure how to do this on the 3B1. /usr/bin/getoff.sh. You'll find that the line works very happily without CD providing you aren't running the HFC drivers. If you *are* then you'll need to fiddle with a second program to do an NDELAY open, or just let the open hang and do an stty clocal from elsewhere. Or wait for the latest HDB which has an NDELAY open as an option (this isn't available outside AT&T yet, alas). -- Jonathan Clark [NAC,attmail]!mtune!jhc An Englishman never enjoys himself except for some noble purpose.