Re: Problems with USB-Serial adapter after upgrade to 2.6.26-1

[u7l11ey@mail.lrz-muenchen.de]

Hi Greg,

thanks for your explanations.

> The port is being opened and then closed right here with the call to
> 'cat'.  That is what I was referring to.

I never thought about what "cat" is really doing here.

> And I would _really_ suggest not using cat for serial data through a
> usb-serial device, over the years it has proven to just not work
> properly.  Use a "real" serial port program, like minicom or something
> else.

I wasn't aware of that either. My approach had been working since I first
experimented with serial communication with my heating controller, the
problems just arose after the latest kernel upgrade.

> Hm, this cat session could still be running at the same time the one
> above was, right?  That's going to be a mess.

I always had one "cat" process reading from the serial port and others
writing to it. Pardon my ignorance.

>> I do suspect that the "stty" commands are causing the problem, but I
>> need
>> to have the port in a defined state before using it. I will test without
>> the stty commands and see what happens, but this can only be a
>> workaround.

It turned out that the stty commands are not causing the problem. It is
reproducibly the "cat" command sending the heating controller the control
sequence to initiate the sending of data over the serial line, however the
problem occurs only in about 10-20% of the time.

> Can you try with a scripted minicom session instead?

I just installed minicom and will investigate its possibilities. I'll
report the outcome.

Thanks again for assisting me.

Regards, Richard