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Null modem for NT --> Xyplex Comm server?

Posted on 1998-06-05
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Last Modified: 2013-12-19

I need a null modem file to allow an NT system to connect to a Xyplex
communications server over a permanent serial link.

The server is always in PPP mode, and the standard modem drivers won't
work, they expect a chat script like response,
  AT<cr>, OK, ....

Which of course won't do anything on a PPP link.

Help or pointers?

Thanks,

Gregory Guthrie
 
PS: I now use Trumpet on W95, which is user scripted, so trivial (no
script!), but trumpet won't work on NT.
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Question by:guthrie
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by:wayneb
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have you tryed dial up networking cable to the com server
from control panel goto modem and add and choose dialup networking cable. It may be worth a shot.
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by:vvk
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After standard (for NT) NULL-modem installed client send "CLIENT" and wait for "CLIENTSERVER". Depends on what your server use for initialization of communication you need to edit mdmhayes.inf file and install NULL-modem. Or if you use NT 3.x edit file modem.inf
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by:guthrie
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Thanks for the note.

Actually I chased this for a long... time on W95; there is a standard null-modem file for it (c/o kewells at Univ. Virginia), but it assumes that the comm server starts out in command mode, and eches a CR back to the dialer.
Ours is locked into PPP mode always.

I tried to adjust the .inf file, but it is pretty wierd, and got complicated.

E.g. init=""      startup="<cr>"
and  init="<cr>"  startup=""
 were not (always) the same, etc...

I also tried to change the xyplex, but if it starts out in interactive (command) mode, it often locked up.

Finally we just went to Trumpet winsock, they have a very simple dialing script, and thus it was trivial to not dial!

Ah..... but Trumpet doesn't port to NT, and it has its own weaknesses.

W/ NT it looks easier, as they support dialing scripts, which W95 didn't. Anyway, I got 5-8 hits on null modem setup instructions for RAS. Unfortunately they are all pretty vague about the assumed context, e.g. host environment expected, and thus the protocol used. I.e. do they try an ASCII handshake before going PPP?

Similarly, the null-modem (direct connect cable) PPP connection of NT/RAS, what does it assume, require? I haven't yet seen any details documented. Now I start it, it "dials" (no phone number), and then gets "error 651; your modem has reported an error". I suspect it tried some command ASCII handshake, send/expect expect sequence, and got no answer. But without any docuemntation, ... ??

inf files are pretty cumbersome, and the packed fields require a tool to create/decode. I'll have to learn more of all the details of this; which I was hoping to avoid! I think NT has dialing scripts, that should make it easier; but how they relate to the table driven .inf dialing sequences, I don (yet) know.

FYI; if you know of any good sources to .inf information, let me know!

Thanks for the note,

Gregory.

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by:vvk
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Try option "bring up terminal window before dialing" to determine what our server answer. If noting recieved edit mdmhayes.inf (not  mdmhayes.pnf) or registry entries to replace responses values with empty string. In other case put server answer in responses.
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by:carmine
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gutrhrie

Try looking at http://www.vt.edu:10021/K/kewells/net/scripts.html

I contributed the CISCO null modem PP driver, they are quite easy to patch to you requirements.
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by:guthrie
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Thanks;

I have it. I tried to edit it several times on W95, getting into the previously described problems,
as I recall, it would do into "dialing..." and never come out.

I need to set it so it sends nothing (actually doesn't matter, PPP protocol will ignore), and then expects nothing, just immediately thinks it is connected. I was not able to get it to do this. I can try the same on NT, but on W95 I couldn't make an .inf to do this.

Are these files same on NT and W95?

Thanks for any info.

Greg
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by:guthrie
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Carmine,

I installed the kewells cisco2 driver, which I think you refer to.

[Strings]
MC = "Mark Crossley v2"

 and find that it installs fine, and shows up on the modem list, but is not available on
the RAS available modems list. ??
The MSoft "serial cable" modem is on both lists.
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by:guthrie
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Carmine,

I installed the kewells cisco2 driver, which I think you refer to.

[Strings]
MC = "Mark Crossley v2"

 and find that it installs fine, and shows up on the modem list, but is not available on
the RAS available modems list. ??
The MSoft "serial cable" modem is on both lists.
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by:carmine
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guthrie

I think the problem is that CISCO.INF was written for NT 3.51, NT4 and W95 both use the Unimodem driver by default.  I think you can make NT4 use the 'old' style modems for RAS by editing the registry HKLM\Software\Microsoft\RAS\Protocols, add the value EnableUnimodem as type REG_DWORD and set it to 0.

I don't think you can do the equivalent in W95.
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by:guthrie
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Thanks, I'll try it.

This is not a problem on W95.

I saw something on this in the MS KB article Q150808 "disabling unimodem support fo rRAS modems" -- but it's relevance was then not clear to me.

Does setting this mean that only ne .inf files can be used? I worried that I might lose the ability to use existing modems (I have a Supra on another port). Are the two mutually exclusive; i.e. a new null-modem, and a standard modem from their database?

Thanks.
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by:carmine
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guthrie

Sorry but I don't know.  It's some time since I wrote cisco.inf, and the company I worked for then was only using NT3.51 workstations.  I used to have my email address on the web page but I started getting inundated with mails from people trying to get it work on NT4 and W95.  Some of the NT4 people were succesful, but I don't know if they also had unimodem devices configured.

Good luck.
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Accepted Solution

by:
Bing CISM / CISSP earned 100 total points
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M$KB Q122318 may be your needs.

SYMPTOMS
========
 
When you attach a third-party Point-to-Point Protocol (PPP) client to a Remote Access Service (RAS) server via a null modem cable, the RAS server port status reports a hardware failure and no connection is made.
 
CAUSE
=====
 
This problem occurs due to the null modem scripts in the MODEM.INF file being specifically written for Windows NT computers only.
 
RESOLUTION
==========
 
To correct this problem, you can modify the Null Modem entry in the MODEM.INF file for the Windows NT RAS server and the INI extension file for the third-party PPP client.
 
Server Side
-----------
 
Change the Null Modem entry in the MODEM.INF file to the following:
 
   CALLBACK_TIME=10
   DEFAULTOFF=compression
   MAXCARRIERBPS=19200
   MAXCONNECTBPS=19200
 
   COMMAND_INIT=
   NoResponse
 
   COMMAND_LISTEN=
   CONNECT=$
   CONNECT=<h00>CLIENT
   COMMAND_LISTEN=
   NoResponse
 
   COMMAND_DIAL=CLIENT
   CONNECT=SERVER
 
Client Side
-----------
 
For the client side, you want to send a "$" (without quotation marks) to signify a CONNECT. For example, the Chameleon product from NetManage, Inc., uses a SLIP.INI file to send scripts. In the section for Windows NT, change the following lines:
 
   "script=-n" to "script=-n $$ -n" (without quotes)
 
The Chameleon product discussed here is manufactured by NetManage, Inc., a vendor independent of Microsoft; we make no warranty, implied or otherwise, regarding this product's performance or reliability.

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by:guthrie
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Thanks; yes, this is certainly related, but assumes that one can modify the client expect/send sequences. Also, it is for the NT as a server, not a client.

I need to have the NT as client, and the server fixed, with NO handshake prior to PPP.

So, the question is;
how to make a nullmodem.inf file to do that.
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by:Bing CISM / CISSP
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Sorry for so long time haven't response. You mean the two sides are all NT system, either server or workstation? No problem, they can be connected via null modem. What do you mean that how to make a nullmodem.inf file?
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by:guthrie
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cancel this thread, problem solved. answered by alamo; It was very close to your porposed answer, but changing the CONNECT strongs to NoResponse. I don't know why the current thread of comments above is incomplete, and does not show teh last interchanges that solved it.

(Not NT-NT, see the original  note, an NT connectiong to a Xyplex commserver).

Thanks for the help.
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by:Bing CISM / CISSP
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Well, nice to hear you have solved the problem, good luck!
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