RS232 Problems

[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

 

[Chris Tacke, eMVP]

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

 

[Dick Grier]

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.

 

[Mike]

Yeah, putting a null-modem adapter in the picture solved my problem.

Thanks alot for the responses!

Mike