RE: console over modem?

It should be noted that you should only ground one end of the cable,  just like in balanced audio, you could get some pretty nasty AC hum's if you ground both ends...
 
-Mike

________________________________

From: Claus@Monowall [mailto:[email protected]]
Sent: Tue 5/19/2009 3:26 AM
To: Wayne Fiori
Cc: [email protected]
Subject: RE: [m0n0wall] console over modem?



Normally I connect RTS, CTS, RX, TX as one conductor en each pair and connect the 4 other conductors in the pair to GND.

GREEN           RX                           
WHITE(GREEN)             GND
BLUE                     TX
WHITE(BLUE)              GND
ORANGE                   RTS
WHITE(ORANGE)            GND
BROWN                    CTS
WHITE(BROWN)             GND

This configuration lets me run 115200 over 80m in normal server-room conditions.

Claus

-----Original Message-----
From: Wayne Fiori [mailto:[email protected]]
Posted At: Tuesday, May 19, 2009 8:05 AM
Posted To: Monowall
Conversation: [m0n0wall] console over modem?
Subject: Re: [m0n0wall] console over modem?

Considering the difference in data rates and signaling, re ethernet
versus serial, the wire pair twists are not important in the serial
cable. They are important for ethernet however. But even at 9600 baud,
a 15m cable is pushing the length limits.
--
=Wayne


On Mon, May 18, 2009 at 10:54 PM, Mohammed Ismail <[email protected]> wrote:
>
>
> -----Original Message-----
> From: Wayne Fiori [mailto:[email protected]]
> Sent: Tuesday, May 19, 2009 7:51 AM
> To: [email protected]
> Subject: Re: [m0n0wall] console over modem?
>
> The rule of thumb is 15m (or 50ft) before you start to loose line
> rate. The best way to go is a DB-9 to RJ45 adapter. Use a straight
> ethernet cable and do all the pinouts on the adapter
> (http://www.commdevices.com/pdf/null-modem-rj45-db9-pinout.pdf)
> --
> =Wayne
>
>
> =========================
>
> This says the same while using high quality cable.
> http://www.connectworld.net/cable-length.html
>
> also I guess Tx,RX should be on the same pair of cables inside the cat
> cable.
> Just like the Ethernet
> 1 2 3 6   each two in a pair.
> If we did not do it like that, we start to loose rate after 25m on regular
> Ethernet network.
> I have been told that twists do some thing to reduce resistance!
> Any idea?
>
> Mohammed
>
>
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