Seeking modem pinouts (3b1)

[Thaddeus P. Floryan]

bruce at balilly.UUCP (Bruce Lilly) in <1991Feb17.174820.18716 at 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 at 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 at btr.com (OR) {decwrl, mips, fernwood}!btr!thad ]