SUMMARY: Modem/ALM-2 problem

From: Mike Jewison (mjewison@nereid.sal.ists.ca)
Date: Mon Mar 01 1993 - 09:15:43 CST


My original question:

> Dear Sun-Managers.
>
> All of the recent posts regarding modems has been quite informative, but hasn't
> helped me in my current dilemma. We recently upgraded to a Sparc 690MP server
> (SunOS 4.1.3). At that time we moved our ALM-2 board from our old server to
> the new. We have three Practical Peripherals 2400 baud modems connected to
> three of the serial ports on the ALM board. Since the upgrade, although the
> ALM board works just fine with VT-compatible terminals, I have been unable to
> get the modems to work at all dialing out, and only sporadically dialing in.
>
> Here are the entries for the three ports in question, taken from /dev:
>
> a) entries for ALM ports:
> 0 crw-rw-rw- 1 root staff 44, 13 Feb 10 15:48 ttyhd
> 0 crw-rw-rw- 1 root staff 44, 14 Feb 10 15:48 ttyhe
> 0 crw-rw-rw- 1 root staff 44, 15 Feb 10 15:48 ttyhf
>
> b) entries for dialin
> 0 crw--w--w- 1 root wheel 44, 13 Feb 24 21:28 ttyd0
> 0 crw--w--w- 1 root wheel 44, 14 Feb 24 21:30 ttyd1
> 0 crw--w--w- 1 root wheel 44, 15 Feb 24 20:37 ttyd2
>
> c) entries for dialout
> 0 crw-rw-rw- 1 uucp tty 44, 141 Feb 12 12:34 cua0
> 0 crw-rw-rw- 1 uucp tty 44, 142 Feb 12 12:34 cua1
> 0 crw-rw-rw- 1 uucp tty 44, 143 Feb 12 12:34 cua2
>
> The gettytab file hasn't been touched; here are the relevant entries from
> /etc/ttytab:
>
> ttyd0 "/usr/etc/getty D2400" dialup on remote Modem 0
> ttyd1 "/usr/etc/getty D2400" dialup on remote Modem 1
> ttyd2 "/usr/etc/getty D2400" dialup on remote Modem 2
> cua0 "/usr/etc/getty D2400" unknown off remote
> cua1 "/usr/etc/getty D2400" unknown off remote
> cua2 "/usr/etc/getty D2400" unknown off remote
>
>
> The problems we have encountered thus far are:
>
> 1) When dialing out using kermit (kermit -l /dev/cua1 -b 2400), an error of
> the type:
> /dev/cua1: Device busy
> C-Kermit, 4E(070) 29 Jan 88, 4.2 BSD
>
> is returned. Always. For all three ports.
>
> 2) When attempting to dial in, the modem will always pick up, you'll get
> connected, but there is no prompt from the server. You're just hung there
> and the only solution is to hang up and try again. Several users have
> reported that they have been able to log in after two or three attempts; I
> have been successful at all.
>
> The modems are connected to the ALM ports via 25-pin ribbon conductors. This
> setup worked well with our old 4/280 running SunOS 4.1.1, but doesn't work
> worth a damn now.
>
> I'm appreciative of any assistance offered and, as always, I'll summarize.
> Many thanks.
>

Several different suggestions were given, many of them dealing with
ttysoftcar(8). The solution to our problem was provided by Chuck Smoko, who
mailed me a PostScript document entitled "Guide to Asynchronous Serial Lines",
written my someone named Hal Stern :-). In order for a port with a modem to be
used for both dial-in and dial-out you must enable hardware carrier detect. To
do this, the "flags" value in the kernel configuration line for the ALM board
must be set to 0 for each port that is to use hardware carrier detect. In our
case, the line was changed from:

        device mcp0 at vme32d32 ? csr 0x01000000 flags 0x1ffff priority 4

to:
        device mcp0 at vme32d32 ? csr 0x01000000 flags 0x11fff priority 4

since we are using ports d-f on the ALM board for the modems. Rebuilding the
kernel and rebooting fixed our dial-out problem totally. As a side effect,
perhaps, people have been reporting fewer dial-in problems as well.

The reason it worked on the old server was because I didn't install the ALM
board on the old server. I checked the kernel for the 4/280 and, sure enough,
the above mentioned kernel modification had been made. Ah well.

My thanks to all who responded:

deb@beaux.ATWC.Teradyne.COM (Deborah Heller)
<Jonathan.C.Davis@acenet.auburn.edu>
peter@key.amdahl.com (Peter Sivo)
csmoko@relay.nswc.navy.mil (Chuck Smoko - K31)
winters@ct.med.ge.com (Steve Winters 5-5784)
jpd@ucs.usl.edu
peterg@murphy.com (Peter Gutmann)
ups!upstage!glenn@fourx.Aus.Sun.COM (Glenn Satchell - Uniq Professional

-- 
- Mike Jewison, Systems Manager
  Space Astrophysics Laboratory
  Institute for Space and Terrestrial Science
  4850 Keele St., 2nd Floor
  North York, Ontario
  CANADA   M3J 3K1

Internet: mjewison@nereid.sal.ists.ca Phone: (416) 665-5451 FAX: (416) 665-5497



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