Path: utzoo!attcan!uunet!cs.utexas.edu!uwm.edu!uwvax!astroatc!vidiot!brown
From: brown@vidiot.UUCP (Vidiot)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Connecting printer thru serial port
Message-ID: <535@vidiot.UUCP>
Date: 14 Jun 90 04:27:11 GMT
References: <90163.165653TEB106@psuvm.psu.edu>
Reply-To: brown@vidiot.UUCP (Vidiot)
Organization: Vidiot's Hangout
Lines: 32

In article <90163.165653TEB106@psuvm.psu.edu> TEB106@psuvm.psu.edu (Tom billet) writes:
<We have a Digital LetterPrinter 210 which was previously used as a printer
<connected to a VT220 terminal (connected to an IBM Mainframe).  The VT220
<terminal was traded in on an IBM PS/2 Model 50Z, and we would now like to use
<the printer with the new PC.  The only problem is that the printer only has a
<serial port.  I tried connecting the printer thru the serial port and can not
<get it to work.  I tried setting the dip switches and altering the different
< parameters but I am still far from getting it to work.  I called the DEC
<support group and they said that pins 2 & 3 (send and receive) had to be revers
<ed (like a null modem does for a PC to PC connection).  I couldn't believe
<that they should be reversed, but I tried it anyway and it still didn't work.
<Does anyone have any suggestions for things to try.  Thanks in advance.

They are correct in that a null modem needs to be obtained.  The printer
is a DTE device, as well as the PC.  You cannot connect two DTE devices
together.

But, not only do pins 2 and 3 have to be messed with, but so do a few others.
Go to Radio Shack and get on of their null modem adapters.  It should solve
part of your problem.

You also have to worry about handshaking between the printer and the PC.
If the printer uses XON/XOFF, the odds are that the DOS you are using
doesn't.  Software programs that drive the COM port directly will normally
has handshaking built in.  If the program tells you to set the com port
using the DOS MODE command, it probably doesn't.

These are the things to keep in mind.
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