Subject: Re: stty crtscts < /dev/ttyS1

From: Giuliano Pochini <[email-masked]>
Date: Sat, 08 Apr 2000 20:20:41 -0400

> >What is connected to the serial port ?  When I enable RTS/CTS on ttyS1
> >and there is my Epson 740 attached, the whole system freezed.
>
> Same thing attached.

It could be a bug in the serial driver, but I don't think so. BeOS hangs
same way (although it's likely Be people "ported" Linux code into BeOS...).
I spent a couple of days around the serial driver and I didn't find any bug.
BTW under MacOS it works fine :-/  so what ???

> >I don't
> >know why this happen exactly. It seems that the printer changes continuosly
> >with very high frequency  the state of CTS, which cause the serial driver
> >to loop indefinitely.
>
> Ouch! Broken hardware... how can I document this is happening, so that
> I can demand an answer from Epson ?

To print under Linux I wrote a small prg which sends data to the printer very
slowly bacause I couldn't find a way to know when the printer buffer gets
filled. Somewhere at Epson (about older printers) I read that it should use
starndard rts/cts flow control.
Ah, I send data at 230400bps 8N2 (*2* stop bits) because the printer don't
seem to be able to receive data so quickly (again, no problems with 8N1
under MacOS).

> Or maybe I should just hack the serial driver to ignore this.

:-6

> And WTF
> is the serial driver doing looking at CTS on a port with no data?!

CTS changes cause and interrupt.

Bye.

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