Re: com port problem

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From: w_tom (w_tom1_at_hotmail.com)
Date: 12/10/04 

Date: Fri, 10 Dec 2004 15:42:40 -0500

  If the DOS or Windows 9x program used standard data transfer
principles, then the serial ports should have worked just fine
in XP. XP serial ports work fine even with DOS programs if
the DOS programs used standard access methods. However some
wanted to do weird things especially with handshake lines that
is not standard use.

  Quite possible that problem is not the software. Quite
possible it is how the serial port defaults. For example, a
peripheral needs a line hung in a certain direction. That
line was left in a default state when running Windows 9x.
However same port left in a state in Windows 98 will instead
be put by Windows XP to what should always have been the
default state. Then the peripheral does not work.

  Remember, serial port used in PCs is a non-standard
standard. Numerous implementations are based upon default
states that violate RS-232. We use those serial ports most
often for functions that the RS-232 was not intended.
Therefore, I made some good money by taking an oscilloscope
and learning how every unique serial port was setup.

  The original RS-232 was only for a Data Terminal Equipment
(DTE) to talk to a Data Communication Equipment (DCE being a
modem). You are already using it for a function it was not
intended. We do this often. What you have is a kludge
application of that RS-232 function. Made more complex if the
controller uses those other handshake wires. Therefore learn
details of what those other signal wires must be or be set
at. Windows 98 application software could have left DTR
sitting high but XP automatically leaves it low. Had the
program used serial port in a more standard way, then it would
have worked just fine in XP. I still use DOS programs I had
written long ago on XP and other Windows NT based systems.

  Too many unprovided details to really answer your question.
You must provide such signaling details to get a useful
answer.

stu96art wrote:
> I am working on converting software over to XP. This is just an
> example and I figured that if I could get this to work, then I
> could have a heads up on the other. Thanks for your help, and
> any further assistance is greatly appreciated.

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