bruce@balilly.UUCP (Bruce Lilly) (02/18/91)
In article <1991Feb13.172049.21792@progress.com> andy@progress.COM (Andrew Klein) writes: >I have a 3b1 but no documentation. Can anyone provide >me with the recommended cable pinnings for an external >modem? Your help is much appreciated. I'm posting, beacause this should help answer another recent poster's question regarding modem connections. function 3b1 pin modem pin frame gnd. 1 ___________ 1 TD 2 ___________ 2 RD 3 ___________ 3 RTS 4 ___________ 4 CTS 5 ___________ 5 DSR 6 ___________ 6 signal gnd. 7 ___________ 7 CD 8 ___ DTR 20 ___|_______ 20 TC 15 ___________ 15 RC 17 ___________ 17 RI 22 ___________ 22 ETC 24 ___________ 24 -- Bruce Lilly blilly!balilly!bruce@sonyd1.Broadcast.Sony.COM
thad@public.BTR.COM (Thaddeus P. Floryan) (02/19/91)
bruce@balilly.UUCP (Bruce Lilly) in <1991Feb17.174820.18716@blilly.UUCP> writes:
I'm posting, beacause this should help answer another recent poster's
question regarding modem connections.
function 3b1 pin modem pin
frame gnd. 1 ___________ 1
[...]
CD 8 ___
DTR 20 ___|_______ 20
TC 15 ___________ 15
RC 17 ___________ 17
RI 22 ___________ 22
ETC 24 ___________ 24
I disaggree with that wiring of DTR to CD at the 3B1 end. It is MOST
important for the 3B1 to be able to detect when the modem:
1] connects, via its CD signal going true, and
2] disconnects, via its CD signal going false.
In my response to andy@progress.COM I posted the correct cable pinnings for
use with a modem and for use with a terminal; that posting should have been
just a few articles before this one.
One of my companies makes a "device" that interfaces modems to host computers
with most of the sales going to phone companies and the DoD, so I'm no "babe
in the woods" concerning modems. I have tested hundreds of different modems
over the years and can just about solve any modem-related problem that you
can imagine; you shoulda seen the response I received earlier this evening
from a guy pleading for help with a modem that hasn't been made since 1978 and
I was able to produce ALL the docs he needed from my files! :-)
My product even includes the capability of autobauding from 300-19,200 using
an asynchronous UART (MC68681); if you don't understand why I mentioned that,
don't bother asking because it's a trade secret and has caused all competitors
(incl. Lockheed and other biggies) to drop out of this line of business (after
they pooped their pants! :-)
The ONLY real "problem" I've had with modems has concerned the HDB UUCP
software suite re: the frustrating "Cannot connect to device" problems, which
now, after resolving all the documentation errors, are easy to fix in the
software config files. If you have a problem in that regards, post the
question and I'll reply; I just fixed another person's system several days ago
which requires use of not-well-documented tricks in the Devices and Dialers
files and requires about 30 seconds with an editor once one knows HOW to do it
(for those who remember my "even put Mother Theresa on a killing rampage"
criticism of HDB two years ago :-)
Thad Floryan [ thad@btr.com (OR) {decwrl, mips, fernwood}!btr!thad ]