nolan@tssi.UUCP (Michael Nolan) (04/16/91)
Recently I purchased a Telebit T1600 modem for my Tower/450, O/S release
2.01.00 (SVR2). Because the question of how to configure a modem has come
up repeatedly in this group, I thought I'd summarize my findings. I have
been able to get the modem to work as both a dial-in and dial-out device,
both with cu and with uucp.
Here is the modem configuration I'm using on the T1600, after some
assistance from Telebit Tech Support (1-800-TELEBIT):
T1600 - Version LA1.00 - Active Configuration
B1 E0 L2 M0 Q2 T V1 X12 Y0
&C1 &D3 &G0 &J0 &L0 &Q0 &R3 &S2 &T4 &X0
S000:1 S001=0 S002=43 S003=13 S004=10 S005=8 S006=2 S007=40
S008=2 S009=6 S010=14 S011=70 S012=50 S018=0 S025=5 S026=1
S038=0 S041:1 S045=0 S046=0 S047=4 S048=0 S050=0 S051:254
S056=17 S057=19 S058:0 S059=0 S060=0 S061:0 S062=15 S063=0
S064:1 S068:3 S069=0 S090=0 S093=8 S094=1 S100=0 S102=0
S104=0 S105=1 S111:30 S112=1 S180=2 S181=1 S183=25 S190=1
S253=10 S254=255 S255=255
Some comments on the T1600 register setup:
1. The &S2 register is because uugetty (or something) on my system doesn't
kill the process when the phone line drops unexpectedly. This is a
security problem, so I've set it to drop carrier briefly when the
connection breaks. (The S47 register controls how long, I'm using the
default setting.) I also have the gettydefs entry for that device
set to 'hupcl -clocal'. THe -clocal doesn't really seem to be doing
much, but that's what NCR Remote Support recommended. I didn't solve
the hangup problem until I used &S2. Since most 2400 baud modems
don't have &S or &S2 or S47, this solution may not work unless you
have a high speed modem. (The problem doesn't seem to happen on
a getty device, only on a uugetty device.)
If your modem supports &S1 (DSR on only after answer tone detected and
throughout the connection) but not &S2, there is potentially another
solution involving the ;N option in the Devices file. This worked
but I wasn't always able to get dialing out to work, so I went to
the &S2 solution, which also solves the problem and dials out better.
I believe the problem with &S1 is a bug, and I've reported it to CODAR.
2. The S51, S58, S61, and S68 registers set the modem to a locked interface
speed of 19200 with the local DCE. If your system supports 38400 over a
serial port (mine doesn't) then you could use S51=6 instead. The modem
negotiates the fastest possible speed on any incoming call, but always
communicates with the local system at 19200. This means that the gettydefs
entry is a single baud rate (19200).
3. I've got S45 set to 0 to disable remote modem access. This means that
the remote modem can't fiddle with the modem setup.
4. I've got S41 set to 1, which means that the modem will disconnect in
6 minutes (1/10 hour) if there is no activity.
5. When I want to make an outgoing call at a speed lower than the maximum
the modem can negotiate, I set the S50 register before dialing.
For example, I use S50=3 when dialing one of the national BBS services,
because I get charged a much higher rate if I connect at 9600 than at
2400.
This are the inittab entries for my modems:
t07:1:respawn:/usr/lib/uucp/uugetty -h -r3 -t 60 tty07 K vt100
ta:1:respawn:/etc/getty ttya A vt100
ttya is for the remote support modem, although I've also got an Everex 2400
baud modem on this port for the 99.9% of the time that I'm not using
remote support. From the documentation, it appears that ttya cannot support
speeds higher than 2400 (more likely, it's too slow to be recommended), and
I've not been able to use ttya for both dial-in and dial-out, so I've got
it set for dial-in only.
Here are the relevant gettydefs entries:
A# B2400 ISTRIP CS7 PARENB NL1 CR1 ECHO # B2400 HUPCL PARENB TAB3 ECHO SANE #login: #A2
A2# B1200 ISTRIP CS7 PARENB NL1 CR1 ECHO # B1200 HUPCL PARENB TAB3 ECHO SANE #login: #A
K# B19200 ISTRIP CS7 PARENB NL1 CR1 ECHO -CLOCAL # B19200 HUPCL -CLOCAL PARENB TAB3 ECHO SANE #login: #K
I'm using special Dialer entries, mostly for convenience:
#
# TELEBIT T1600 MODEM
#
t1600-1200 =,-, "" \d\d\dAT OK\r \dATS50=2Q0\r\c OK\r ATDT\T\r\c CONNECT
t1600-2400 =,-, "" \d\d\dAT OK\r \dATS50=3Q0\r\c OK\r ATDT\T\r\c CONNECT
t1600-19200 =,-, "" \d\d\dAT "" \dATQ0\r\c OK\r ATDT\T\r\c CONNECT
For some reason, the modem doesn't respond to the first AT command sent
to it in the 19200 Dialer entry, which is why I've set it to not require
any response from that command. This problem doesn't occur for the 1200
and 2400 dialout entries, and I can't explain why not.
These of course, require special Devices entries:
ACU tty07 - 19200 t1600-19200
ACU tty07 - 2400 t1600-2400
ACU tty07 - 1200 t1600-1200
Direct tty07 - 19200 direct (so that cu -l tty07 works)
------------------------------------------------------------------------------
Michael Nolan "Software means never having
Tailored Software Services, Inc. to say you're finished."
Lincoln, Nebraska (402) 423-1490 --J. D. Hildebrand in UNIX REVIEW
UUCP: tssi!nolan (or try sparky!dsndata!tssi!nolan)
Internet: nolan@helios.unl.edu (if you can't get the other address to work)