[CentOS] Need to test serial port connection

Thu Feb 26 20:41:14 UTC 2009
William L. Maltby <CentOS4Bill at triad.rr.com>

On Thu, 2009-02-26 at 14:29 -0600, Robert wrote:
> <snip>

> breakout box.  Lacking one of those, you might find the statserial 
> program to be of some use in figuring out what the control lines are doing.
> #  yum --enablerepo=dag install statserial
> will install it.  It has a short man page.   Run with no options except 
> device ( # statserial /dev/ttyS0 )  will cause it to loop, indicating 
> status of all control signals.   You can manually tweak any of the pins 
> with direction of "in" with a 9-volt battery or by using a paper-clip 

IIRC (very iffy) +/- 12 volts is needed.

> jumper from one of the "out" lines.  It won't be long before you can 
> identify the port, moving an "unknown" to "found". 

There are pins designated to _provide_ the correct voltage full time (on
25 pin units - unsure about 9 pin). The google will get a specification
of which they are - I can't remember.

> 
> Good luck!
> <snip>