From: am518@cleveland.Freenet.Edu (Jeff  Wisniewski)
Subject: *** Help requested with AutoCad V11 ***
Organization: Case Western Reserve University, Cleveland, Ohio, (USA)
Date: Sat, 22 Aug 92 16:12:13 GMT


I am having a problem with AutoCad and am turning to the net for some
assistance.  Any help would be greatly appreciated.
 
 
First some background info:
 
     We have AutoCad Version 11 running on a 486 and a Hewlett Packard
     DraftPro DXL plotter.  We do not have a LAN but we do have a 386
     computer in another room.  We have 4 pair twisted cable running
     throughout the building that all home-run back to a patch panel.
 
 
What I want to do:
 
     Hook up the two PCs to the same plotter using the existing cable
     and an auto-select switch box.  
 
 
Start a bit into the problem:
 
     I left out a bit of background info.  We also want both of the PCs
     to share a printer with the mainframe.  This has been accomplished
     with another auto-select switch box.  To save cabling costs, I used
     a splitter to sperate the 4 pair into two 2 pairs.  This way I can
     use the one cable for both the printer and plotter.  Since the
     plotter is serial this should work fine.  The printer works great
     this way.
 
     Since I now only have 4 wires for the plotter, obviously I had to
     cut out a few.  I did this and now have it down to 2 pair. 
 
 
What DOES work:
 
     -    The plotter does work fine with the cabling and the auto-select
     switch running in "scan mode" with Harvard Graphics.
 
     -    The plotter will work in AutoCad if the auto-select box is selected
     to the port that will be doing the plotting before you actually start to
     plot.
 
 
What DOES NOT work:
 
     -    AutoCad will NOT plot if the switch is in auto-select mode.
 
 
What I have done:
 
     I put a breakout box between the auto-select port that the PC was
     patched to and the PC.  I put the auto-select box in scan mode.  I
     then sent a drawing from the PC to the plotter and watched the
     lights on the breakout box.  I found that AutoCad does not check
     for any signals to be high before trying to transmit.  The PC
     transmitted without the auto-select box locking in on the port and
     the signals were obviously ignored.  When I tried from Harvard
     Graphics, it would wait until it selected the port and then grab
     the port.  Not true in AutoCad.
 
 
 
My Analysis of the Problem:
 
     My theory is that when you press that return to plot, AutoCad
     transmits some kind of request to the plotter.  It then enters a
     loop and waits for some kind of acknowledgment back from the
     plotter.  It obviously does not check for DTR to be high before it
     does that initial transmit (like Harvard Graphics must do).  Since
     the auto-select box is scanning, unless the box happens to be on
     the right port the message that AutoCad transmitted is lost. 
     AutoCad continues in the loop, still waiting for the acknowledgment
     and not even trying to retransmit.
 
 
Things that I have done to overcome the problem:
 
     I contacted our AutoCad dealer after having the door slammed in my
     face at AutoDesk.  I tried to explain the problem but they didn't
     seem to grasp.  They contacted AutoDesk (supposedly) and came back
     with the suggestion to use AutoSpool and the print command to go to
     the plotter from DOS.  When I do this with the plotter cable
     directly into the plotter it works.  When I go down to 2 pair it
     doesn't.  I get a "Write Fault on COM1" message.  Obviously DOS
     doesn't have all of the signals it would like either!  (You can
     please some of the people.....)
 
 
 
Well, that's it.  Any help would greatly be appreciated.  I guess the best
solution would be for AutoCad to check for DTR before transmitting.  Since I
can't even talk to someone there I doubt I could get some kind of patch.  The
Autospool may work (although a dirty way out) if I change my cable so that
DOS likes it.  Any other ideas?  You can feel free to contact me via e-mail
or our 800 number.
 
 
---
Jeffery L. Wisniewski                                     am518@po.cwru.edu
Independence Excavating, Inc.                                1-800-524-DIRT

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