> "> - Buy a little box with two RS-232 connectors
> > (generally 25 pins,
> > but perhaps there are also 9-pins versions now)
> > with 9 two-color
> > LED's that indicate the state of the 9 most
> > important lines."
>
> Sound interesting..
> Is there a schematic for this device??
for 9-pin version: Ground is pin 5, for 25p it is pin 7.
use some kilo-Ohms resistors, e.g. 2k7, in series with the LEDs.
I built my tester with two separate LEDs per line (2x8 = 16 LEDs). Red LED is
lit with positive voltage, yellow one with negative volts. Separate LEDs have
the advantage over duo-LEDs that one can see even very short impulses, as they
flash on a LED which is normally dark. One can also use e.g. red LEDs only and
mark them with plus and minus sign.
circuit:
res.2k7 from signal pin (2, 3, ...) to Anode.red-LED and K.yellow-LED; K.red-LED
and A.yellow-LED to GND (pin 5 of DSUB-9 conn.)
Mostly 6 LED pairs are sufficient: 2 data lines, 4 handshake lines.
Data lines have normally (no data transmission) negative, handshake lines
positive voltage.
Alois
- - - - - - - - - - - - - - - - - - - - - - - - - -
Alois Bauer
WORK Microwave GmbH
Raiffeisenstr. 12, D-83607 Holzkirchen, Germany
Tel. {+49} (0)8024-6408-0 / FAX (0)8024-640840
--
Author: Alois Bauer
INET: [EMAIL PROTECTED]
Fat City Hosting, San Diego, California -- http://www.fatcity.com
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