RS232 Problems

  • Thread starter Thread starter Mike
  • Start date Start date
M

Mike

Hi,

I'm having some issues with an RS232 device I'm using and have seen
some helpful advice on this group with regard RS232 so am hoping
someone might have some suggestions.

I have an RS232 device that I need to connect to. It's a custom device
we had programmed - without going into too much detail, we pass it
characters, it goes and does things and reports back to us with
characters. When attached to a PC via a 9 pin serial cable, everything
works as expected - I get the responses I expect to the characters I
send. This works as expected with both C++ and C# sample apps.

So then I re-create my samples and run them on a CE.NET device (X86
platform) and nothing - I cannot get the external device and the CE
device to talk to each other. I know the serial port on the CE.NET
device is working as I can connect it up to a PC and transmit
characters between the PC and the CE.NET device using Hyperterminal on
the PC and a simple C# app on the CE.NET device.

So I can't figure out if the problem lies with my RS232 device that
I'm trying to communicate with (works with a PC but not with a webpad)
or my webpad (works talking to a PC but not to my RS232 device). I
tried setting the DTR flag on the webpad software as I understand from
previous postings that this might help but it didn't.

I have to admit that I'm stumped - I'm going to go get one of those
devices you can put inline on the RS232 line and see if I can figure
out what's different between the PC talking to the device and the
webpad talking to the device.

Does anyone have any suggestions as to any config changes I can make
or anything extra I can test to help me figure out the problem

Many thanks

Mike
 
A logic analyzer or a scope would help you determine if it a handshaking
issue (which it sounds like). Does the device expect power on DSR or RTS
(like a mouse)? You might check to see if the state of these is different
between the PC and the PPC.

-Chris
 
Hi,

If you have recompiled for the target platform... My guess is that your
cable needs work. I suspect that you need a null-modem connection. You can
use a null-modem cable, or purchase a null-modem adapter (about $5).

Dick

--
Richard Grier (Microsoft Visual Basic MVP)

See www.hardandsoftware.net for contact information.

Author of Visual Basic Programmer's Guide to Serial Communications, 3rd
Edition ISBN 1-890422-27-4 (391 pages) published February 2002.
 
Yeah, putting a null-modem adapter in the picture solved my problem.

Thanks alot for the responses!

Mike
 
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