Article 64720 of comp.os.vms:
Path: cs.utk.edu!gatech!swrinde!network.ucsd.edu!mvb.saic.com!info-vax
From: Mighty Firebreather <dragon@nscvax.princeton.edu>
Newsgroups: comp.os.vms
Subject: RE: Modem cable pinout
Message-ID: <0096BD8B.C1EDF660.18110@nscvax.princeton.edu>
Date: Sat, 01 May 1993 09:30:45 EDT
Organization: Info-Vax<==>Comp.Os.Vms Gateway
X-Gateway-Source-Info: Mailing List
Lines: 132

	<karl@bagpuss.demon.co.uk> writes:
>
>Whenever I connect a modem to my uVax, via a DHV/11, I get the following
>OPCOM message:
>
>%LOGIN-F-NOTMODEM, VAX/VMS host system modem not wired correctly -
>contact your system manager
>
>I understand this is due to the enforcement of new signal requirements
>in VMS 5.2 or 5.3.  Can anyone suggest the correct pinout for a correctly
>wired cable ?
>

	I guess it's time to repost this.  It's been a couple of years.

------------------------------------------------------------------------------

                      Using a MODEM With Your VAX
                          Richard B. Gilbert
                          Revised May 1, 1993

	Be sure that the serial port you are using supports MODEM control
signals.  On the DMF32, for example, only ports 0 and 1 can be used with
MODEMS.  These ports on the DMF32 must have switches set to enable MODEM
control signals.  The VAXStation 3100 does NOT support MODEM control!  The
MicroVAX 3100 does support modem control. 

	Connect the MODEM with a cable that supports MODEM control signals
such as DEC's BC22E.  Note that while it was possible to "fake it" with VMS
V4.x and earlier, VMS V5 requires that all of the MODEM control signals be
connected.  (Pins 2-8, 20 and 22 should be connected straight through;
i.e., 2-2, 3-3, 4-4, ...) 

	You will need to make some switch settings on your MODEM.  The
following settings are for a US Robotics Courier 2400.  See your MODEM's
instruction manual.  The switch numbers will be different but the functions
available are typical.  The settings marked with an asterisk are critical
to the successful use of your MODEM.  Some settings can also be made from
the CPU via the MODEM's AT command set, in which case the hardware switch
settings determine the MODEM's power on defaults.  The AT commands in
parentheses, following the switch settings, are the commands for a U.S.
Robotics Courier HST dual standard modem.  Check your manual for the proper
commands for your modem. 

* 1.  DTR Normal (controlled by CPU)			(AT&D2&W)
  2.  Verbal result codes (Useful during dialout)	(ATV1)
* 3.  Do not display result codes (Quiet mode)		(ATQ1)
  4.  Echo off line commands (Useful during dialout)	(ATE1)
* 5.  Auto answer (MODEM will answer the phone if DTR is asserted) (ATS0=1)
* 6.  Normal Carrier detect (controlled by MODEM)	(AT&C1&W)
  7.  Single phone line (As required)
  8.  Normal At command set (Must be enabled for auto dial.)
  9.  Online after +++

************************************************************************

	Many users have observed the VAX dropping DTR (Data Terminal Ready)
while a user is trying to dial in, causing the MODEM to hang up the phone.
The terminal driver will drop DTR if it sees DSR (Data Set Ready) for more
than thirty seconds, without also seeing CD (Carrier Detect).  If it is
possible to configure the MODEM so that it does not assert DSR until it
asserts CD (AT &S1&W), do so.  Otherwise it will be necessary to use a
modified cable. At the VAX end of the cable, cut the wire leading to pin 6
(DSR) and jumper pin 6 to pin 8 (CD). 


	A command similar to the following should be placed in your 
SYS$MANAGER:SYSTARTUP_V5.COM file to set up an asynchronous port for use with
a MODEM.  You may want to add some more qualifiers but this will get you going.
$	SET TERMINAL -
	/PERMANENT -	! Make settings permanent
	/MODEM -	! Use MODEM control signals
	/DIALUP	-	! Gives the DIALUP identifier to user.
	/HANGUP	-	! Hang up the phone when user logs off
	/AUTOBAUD -	! Detect the user's baud rate and set it.*
	/ALTYPEAHD -	! Use the alternate typeahead buffer.  The
			! alternate typeahead buffer can be made larger
			! than the regular one.  This is helpful if you
			! are doing file transfers.  See SYSGEN parameter
			! TTY_ALTYPAHD.
	/HOSTSYNC -	! VAX will send XOFF when its buffer is nearly
			! full and XON when it is ready for more input.
			! See SYSGEN parameter TTY_ALTALARM.
	_TXA0:

$	SET PROTECTION=W:R /DEVICE
			! Sets device protection to allow non-privileged
			! users to allocate the device for dialing out.
			! Otherwise user must own device or hold SYSPRV.

	* Many modern modems are capable of using a fixed DTE rate to talk
to the computer; e.g. if they are set to 19200, they will talk to the 
computer at 19200 regardless of what speed they are using to talk to the 
remote modem.  This feature has performance implications for modems that do
data compression using either CCITT V.41 or MNP.  For such modems, use
/SPEED=xxxxx rather than /AUTOBAUD.

************************************************************************

	The following commands should probably go in SYS$SYLOGIN, your 
system-wide login command file:

$! Test for interactive or batch mode
$!
$	IF F$MODE() .NES. "INTERACTIVE" THEN GOTO 10$
$!   Set up device dependant terminal characteristics.  This only works
$! if the terminal responds to ANSI Device Attributes (DA) control string.
$! Most DEC terminals (VT1xx, VT2xx, LAxxx) and compatibles will do so.
$	IF F$GETDVI("TT", "TT_MODEM") THEN $ SET TERMINAL /INQUIRE
$ 10$:
**************************************************************************

	To set the terminal for temporary dialout use, execute the following
commands:
$	ALLOCATE TXA0:	KER$COMM	! Logical is useful for Kermit-32.
$	SPEED="''P1'"
$! Default to 1200 baud.		! Pick a suitable default value.
$	IF SPEED .EQ. "" THEN SPEED=1200
$	SET TERMINAL /NOAUTOBAUD /SPEED='SPEED' KER$COMM:

	You may need to add a /NOECHO qualifier if your terminal program is too
stupid to read with no echo.  It is not necessary with SET HOST/DTE, 
KERMIT, XMODEM, or HOST32.

*************************************************************************
*                                                                       *
*                        Here, there be dragons!                        *
*                      dragon@nscvax.princeton.edu                      *
*                                                                       *
*                                                Richard B. Gilbert     *
*************************************************************************



Article 112944 of comp.os.vms:
Path: cs.utk.edu!stc06.ctd.ornl.gov!fnnews.fnal.gov!uwm.edu!news.alpha.net!news.mathworks.com!gatech!newsxfer.itd.umich.edu!jobone!ef2007!fiesta.srl.ford.com!pt9201.ped.pto.ford.com!pt9113.ped.pto.ford.com!FULLER
From: fuller@pt9113.ped.pto.ford.com
Newsgroups: comp.os.vms
Subject: Re: That annoying DTR timer...
Date: 23 Apr 1995 16:34:28 GMT
Organization: Ford Motor Co., Powertrain Electronics
Lines: 51
Message-ID: <3ndvik$smk@pt9201.ped.pto.ford.com>
References: <950423010205.220001f1@vaxherd.bdsnet.com>
Reply-To: fuller@pt9113.ped.pto.ford.com
NNTP-Posting-Host: pt9113.ped.pto.ford.com

In article <950423010205.220001f1@vaxherd.bdsnet.com>, Jim Bender <JBENDER@vaxherd.bdsnet.com> writes:
>
>
>We have a number of late model 28.8k baud modems hung off of DMB32's on
>a Vax 8800.  VMS has this nasty little habit of cycling the DTR line on
>modem ports every thirty seconds.  

Actually, VMS is doing what it is documented to do in the I/O User's Guide, the
chapter on terminal devices.  The problem is usually that the modems have this
nasty habit of not being configured correctly for dial-in access.

You need to read the modem's user guide for how to do this.  You need to
configure the modem to:

	- correctly respond to DTR
	- correctly control the DSR signal
	- correctly control the DCD signal

The problem of cycling DTR every 30 seconds is most commonly due to the DSR
signal being high/active all the time.

The way that dialin access works is:

start:
	- host lowers DTR for 2 seconds to clear the line
	- host raises DTR
		- this tells the modem to answer the phone on the next ring
	- phone rings
	- modem raises DSR to indicate an incoming phone call
	- host starts 30 second timer to wait for DCD active
	- modem negotiates with caller's modem
	- if negotiation successful, modem raises DCD
	- host starts another 30 second timer for login attempt
	- if login successful, go to success
	- if negotiation unsuccessful, the DCD 30 second timer times out
		- go to start
success:
	- user works on the system
	- user logs out
	- go to start

Basically, what's happening is that if DSR is up all the time, VMS thinks that 
the phone is offhook (active) all the time, and is trying to hang it up.

+===================+========================+================================+
|    ____           | Stuart R. Fuller       | fuller@pt9113.ped.pto.ford.com |
|   /   /           | Digital Equipment Corp.| fuller@gldoa.enet.dec.com      |
|  /____  _/_       | Detroit, MI, USA, Earth| 76703.501@compuserve.com       |
|      /  /   /   / +========================+================================+
| /___/  /_  /___/\ |     Opinions expressed here are mine, and mine alone    |
+===================+=========================================================+


