Re: Serial (RS232) communication - failing to detect stop bit

Robert and David, thanks for your replies.

I have not programmed anything myself, I am using the terminal program
Minicom between the machines. I'm sorry, I left out some key points
so I will summarize it again with the background information:

1) The ultimate objective is to use the Gentoo machine to collect data
from an external instrument (via serial cable cable connection).

2) It didn't work, indicating that there is a problem with serial
communications on that machine. Another factor that points to this
possibility is the fact that we had the same problem on the Gentoo
machine at my client's site. My machine was set up using an HDD image
from his machine so the software environment is the same.

3) In order to diagnose this I bought the cross cable, and set up
Minicom on both machines to see if I can send text (such as "hello
world") back and forth between the machines. Needless to say I have
set the exact same settings (baud, parity, stop bit, flow control,
linefeeds, local echo, etc) on both sides.

4) Characters from PC-2 (the Gentoo box) to PC-1 (the Xandros box)
transfer fine. They show up in Minicom on Xandros. However the
reverse is not the case, nothing I type on Xandros shows up in Minicom
on Gentoo.

5) On the command line of Gentoo I type
# cat /proc/tty/driver/serial
and it tells me the number of bytes transfered by rx and tx.
Both are correct, the tx value is indeed the number of bytes I have
typed on that machine, and the rx value is indeed the number of bytes
I have typed on the Xandros machine. So this indicates the data is
being received, just not showing up in Minicom. I also get fe:2,
which I assume means two frame errors.

6) Some other relevant observations:

- The Xandros PC also has a Windows XP partition, and I tried the
exact same thing on Windows using Hyperterminal. It was the exact
same situation - I could send from Gentoo to Windows but not from
Windows to Gentoo.

- On the Gentoo machine I also tried communicating with the other PC
using MATLAB instead of Minicom. MATLAB is a sophisticated
mathematical modeling package but its command line has some high-level
commands to send and receive from the serial port. Sending was
successful but receiving wasn't, just like in Minicom. In MATLAB when
I would try to receive I would get a message to the effect that it
timed out without detecting a terminator. (this may be the stop bit?)


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