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

arka.n.roy wrote:
Sorry David, I may have mistakenly pressed "Reply to author" and it
went to you as a mail.

Here it is again, so that everyone can see it.


On Aug 26, 9:26 am, David M <NOS...@xxxxxxxxxx> wrote:
On Sat, 25 Aug 2007 18:45:03 +0000, arka.n.roy rearranged some electrons
to form:


The rx figure is correct in that it jives with the number of bytes I
sent from PC-2... this indicates that the Gentoo machine IS receiving
data. However maybe the fe:2 means that it is not detecting the stop
bits, and this is preventing it from displaying output text in
minicom.
Not likely. If you were not detecting the stop bits, you would see many
framing errors, not just 2.


When I do a
# cat /proc/tty/driver/serial
I wonder if the "fe:2" that gets displayed really means there were 2
instances of not detecting the stop bit or if it is just a fixed value
that gets displayed if such a thing occurred at all in the last
received data.

I set Minicom to send breaks.
# cat /proc/tty/driver/serial
displays "brk:1" in this case. However it continues to display 1,
even though I continue my experiment (meaning that I continue sending
breaks). This value doesn't increase. I am wondering if the fe value
may be something like this.


Even old kernels can use serial ports correctly. My guess is that
you have programmed something incorrectly.

This is Minicom, not anything I have programmed. The Gentoo kernel
gets pretty customized when you first set it up. I didn't do it
myself but received it from someone who did, in fact my machine was
set up from an HDD image of his. I am wondering if he made any
mistakes in configuring it... he doesn't seem to know. He is far away
and I have not been able to conduct the same serial port testing on
his machine, but he did the same initial problem as me of not being
able to get data from a measuring instrument via serial connection.

Do you think it is plausible that some kernel (mis)configuration can
cause this?


Try reading this:

http://tldp.org/HOWTO/Serial-HOWTO.html
http://tldp.org/HOWTO/Serial-Programming-HOWTO/index.html


Thanks!


Try sending with two stop bits and receiving with one stop bit.


Robert
.

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