Re: Help:Serial / Parallel Port Control Under Linux

[Grant Edwards <grante@visi.com>]

On 2008-10-03, johnny <johnny@pan-tone.com.sg> wrote:

> Right Now I need to write a simple C code to control the
> serial / parallel port under linux working like this: Detect
> there is an input signal / voltage change and send some output
> signal / voltage accordingly, eg: if DSR is detected to be
> high, I want to set RTS to be high as well; if RI is detected
> to be high, I want DTR set to be low etc.
>
> I have read the Serial-How to and Serial programming-How to,
> however I am still not so clear regarding to this simple
> programming.

Ignore the serial programming howto.  It's out-of-date,
incomplete, unmaintained and just plain wrong in many areas. I
needs to be gotten rid of, but that doesn't seem to be
possible.

A far better source of information is the Serial Programming
Guide for Posix Operating Systems:

http://www.easysw.com/~mike/serial/serial.html

Specifically, the information about modem control and status
lines is in chapter 5.1:

http://www.easysw.com/~mike/serial/serial.html#5_1

-- 
Grant Edwards                   grante             Yow! Inside, I'm already
                                  at               SOBBING!
                               visi.com