[comp.dcom.modems] TB 2500 query

jeffg@orca.WV.TEK.COM (Jeff C. Glover) (10/13/89)

Is there any way to get the TB modem to do an ATZ command upon loss of
carrier?  Several of these stupid modem programs are setting "S0=0" and
then nobody else can dial in after their use.  If ATZ were run after
carrier dropped, everything would be ready for the next user.

Jeff
jeffg%loki.wv.tek.com@relay.cs.net

mike@glisten.UUCP (Michael Wendel) (10/14/89)

In article <4946@orca.WV.TEK.COM>, jeffg@orca.WV.TEK.COM (Jeff C. Glover) writes:
> Is there any way to get the TB modem to do an ATZ command upon loss of
> carrier?  Several of these stupid modem programs are setting "S0=0" and
> then nobody else can dial in after their use.  If ATZ were run after
> carrier dropped, everything would be ready for the next user.
> 
> Jeff
> jeffg%loki.wv.tek.com@relay.cs.net

Try setting register S52 (DTR Interpretation) to a value of 2. When
DTR is turned off, the modem will disconnect the call (if in progress),
and reset itself to the Configuration A/B parameters based upon the 
external switch setting. See the telebit manual for more details.
This feature works quite well, since I can have my tip and uucp
scripts be very dynamic, with option setting, knowing that everything
gets reset when done.

doug@letni.UUCP (Doug Davis) (10/14/89)

In article <4946@orca.WV.TEK.COM> jeffg@orca.WV.TEK.COM (Jeff C. Glover) writes:
>Is there any way to get the TB modem to do an ATZ command upon loss of
>carrier? 

ATS52=2

doug
__
Doug Davis/1030 Pleasant Valley Lane/Arlington/Texas/76015/817-467-3740
{texsun, motown!sys1, uiucuxc!sys1 lawnet, attctc, texbell} letni!doug

philf@xymox.metaphor.com (Phil Fernandez) (10/15/89)

In article <4946@orca.WV.TEK.COM> jeffg@orca.WV.TEK.COM (Jeff C. Glover) writes:
>Is there any way to get the TB modem to do an ATZ command upon loss of
>carrier?  Several of these stupid modem programs are setting "S0=0" and
>then nobody else can dial in after their use.  If ATZ were run after
>carrier dropped, everything would be ready for the next user.

Take a look at enhanced register S52. If S52=2, the modem resets when
an on-to-off transition occurs on DTR.  This recalls the user profile,
which you can set to either the A or B EEPROM profile.

The modem won't answer while DTR is off, but many communication
processors, e.g., Bridge/3Com comm servers, have a configuration to
allow DTR to be toggled on disconnect for just this purpose.  The
toggle will reset the modem and re-raise DTR, making the modem ready
for another call.

pmf

+-----------------------------+----------------------------------------------+
| Phil Fernandez              |             philf@metaphor.com               |
|                             |     ...!{apple|decwrl}!metaphor!philf        |
| Metaphor Computer Systems   |"Does the body rule the mind, or does the mind|
| Mountain View, CA           | rule the body?  I dunno..." - Morrissey      |
+-----------------------------+----------------------------------------------+

wtm@neoucom.UUCP (Bill Mayhew) (10/15/89)

One way to force the T1000 (and should work on the T2500 too) is to
set S52=2.  According to the manual, setting 2 does this:  "The
modem disconnects and reloads operating parameters if DTR is
dropped, and will not auto-answer if DTR is not present."

If using a Unix mahcine, be sure pin 20 (the DTR lead) is connected
through from the host to the modem.  Usually, you can get DTR to
drop by killing the getty for the port and letting the getty
respawn.

I use S52=2 on my Unix PC.  When somebody has been using kermit,
when kermit exits, there is no getty running so DTR drops.  Init
respawns the getty, raising DTR and causing the default parameters
to reload.  I've never had any problems with l'users leaving the
modem in a wierd state.  I used to have a hayes compatible modem,
and people would customarily leave the modem in a goofy state,
locking out uucp.

This is definitely one of my favorite features of the TB modem.
One is out of luck though if the host can't toggle the DTR lead.
In that case, you might have to experiment cross-wiring the RTS
lead to 20 or something.

Bill

jeffg@orca.WV.TEK.COM (Jeff C. Glover) (10/15/89)

Earlier I posted an article where I asked about how to get the TB 2500
to do a reset on loss of *carrier*.  Everybody that replied told me how
to do a reset on loss of *DTR*.  A few implied I should RTFM.  I did
read the _FM_!  Again, I want a reset on loss of carrier, not DTR.  The
modem is on the far end of a chain of networks (ethernet to appletalk
to RS232), and DTR just isn't available.

It looks like it just isn't possible.  The 2400 baud modem that I used
before has this feature, and it only cost $129.

Jeff
jeffg%loki.wv.tek.com@relay.cs.net

arnold@jarthur.Claremont.EDU (Arnold de Leon) (10/16/89)

In article <4974@orca.WV.TEK.COM> jeffg@orca.WV.TEK.COM (Jeff C. Glover) writes:
>[...]  Again, I want a reset on loss of carrier, not DTR.  The
>modem is on the far end of a chain of networks (ethernet to appletalk
>to RS232), and DTR just isn't available.
>
>It looks like it just isn't possible. [...]
>

It is possible.  First, you configure the TB to toggle DSR
when it losses carrier (S130=3, S47 > 0).  (Now for the kludge)
You need a special cable/connector that loops DSR to DTR on the
modem side.   Then, set S52=2 (reset on DTR toggle).

Note DSR will be on even if there is no carrier.  The modem
will still be able to auto answer and originate calls.  But the magic
happens when the modem senses carrier loss, DSR will drop for the 
time specified in S47 (in msecs.) and since DSR was looped back
to DTR, DTR will also get toggled.  

I've discovered that TBs can do just about anything.  The biggest
headache is figuring which knobs to turn!

>Jeff
>jeffg%loki.wv.tek.com@relay.cs.net
-- 

Arnold de Leon                       arnold@jarthur.claremont.edu
Computer Science Dept., HMC          uunet!jarthur!arnold
Claremont, CA 91711                  arnold@hmcvax.bitnet

scotto@pnet01.cts.com (Scott O'Connell) (10/16/89)

doug@letni.UUCP (Doug Davis) writes:
>In article <4946@orca.WV.TEK.COM> jeffg@orca.WV.TEK.COM (Jeff C. Glover) writes:
>>Is there any way to get the TB modem to do an ATZ command upon loss of
>>carrier? 
>
>ATS52=2
>
>doug
>__
>Doug Davis/1030 Pleasant Valley Lane/Arlington/Texas/76015/817-467-3740
>{texsun, motown!sys1, uiucuxc!sys1 lawnet, attctc, texbell} letni!doug

I was about to reply with the same information however Jeff is asking how
to reset the modem on loss of carrier...NOT lost of DTR.

I believe the question remains: can the modem reset to defaults on LOSS OF
CARRIER?  

snoopy@sopwith.UUCP (Snoopy) (10/16/89)

In article <4974@orca.WV.TEK.COM> jeffg@orca.WV.TEK.COM (Jeff C. Glover) writes:
|Earlier I posted an article where I asked about how to get the TB 2500
|to do a reset on loss of *carrier*.  Everybody that replied told me how
|to do a reset on loss of *DTR*.  A few implied I should RTFM.  I did
|read the _FM_!  Again, I want a reset on loss of carrier, not DTR.  The
|modem is on the far end of a chain of networks (ethernet to appletalk
|to RS232), and DTR just isn't available.
|
|It looks like it just isn't possible.  The 2400 baud modem that I used
|before has this feature, and it only cost $129.

You could always try wiring pin 8 to pin 20 and then programming the
TB to be in leave_carrier_detect_high_except_momentarily_after_losing_carrier
mode.

Of course if it drops CD momentarily while resetting you could get into
an infinite loop...

    _____
   /_____\    Snoopy
  /_______\   cse.ogc.edu!sopwith!snoopy
    |___|     sun!nosun!qiclab!sopwith!snoopy
    |___|     uunet!tektronix!tessi!illian!sopwith!snoopy

		"Are you thinking what I'm thinking?"
		"Yeah, LUNCH!"

roe@sobmips.UUCP (r.peterson) (10/17/89)

From article <4974@orca.WV.TEK.COM>, by jeffg@orca.WV.TEK.COM (Jeff C. Glover):
> Earlier I posted an article where I asked about how to get the TB 2500
> to do a reset on loss of *carrier*.  Everybody that replied told me how
> to do a reset on loss of *DTR*.  A few implied I should RTFM.  I did
> read the _FM_!  Again, I want a reset on loss of carrier, not DTR.  The
> modem is on the far end of a chain of networks (ethernet to appletalk
> to RS232), and DTR just isn't available.
> 
> It looks like it just isn't possible.  The 2400 baud modem that I used
> before has this feature, and it only cost $129.
> 

You might be able to wire the TB DSR signal back into its' own DTR
line.  Then, set ATS53=4 and ATS52=2.

The net result should be:
	Modem waits for a call.  DSR is asserted, thus asserting
	DTR, thus allowing the modem to answer the incoming call.

	A call comes in.  DSR does not change, DTR is still
	asserted, CD goes high.

	The call is finished - CD is lost.  The TB will then
	drop DSR for the amount of time specified in S47 - so,
	dropping DTR for itself.  This should cause an ATZ
	EEPROM reload.

You may need to muck about with S47 to find the right amount of
time to drop DSR.

Let me know via email (at the address below) if this really works.

-- 
					Roe Peterson
					{attcan,mcgill-vision,telly}!sobeco!roe