[aprssig] RJ45/RS232 Again

Fred Atkinson, WB4AEJ fred at wb4aej.com
Mon Mar 13 15:37:57 CST 2006


    OK, let me be more specific.  If you are familar with using a crossover
cable to connect the serial port of a PC to a Cisco router, switch, or
firewall,  you will have no trouble following this.

    I use Cisco rollover cables a lot because I teach computer networking.
I want to make an adapter to adapt the leads in a Cisco rollover cable to
the RS232 interface on a TNC-2.  Therefore, the same cable I use to
interface to Cisco devices I will be able to use [with this adapter] to
connect to the RS232 port on a TNC-2.

    A rollover cable is called just exactly what the pin out describes.  It
is as follows:

                     RJ45   to  RJ45
                       1    to    8
                       2    to    7
                       3    to    6
                       4    to    5
                       5    to    4
                       6    to    3
                       7    to    2
                       8    to    1

    Generally, you have a DB9 to RJ45 female adapter on your computer's
serial port, a rollover cable, and then the other end of the rollover cable
mates with the console (serial) port on a Cisco device.

    I have a few RJ45F to DB25M adapters from our good friends at Jameco.
Of course, you get the honor of setting the pins yourself.  I am trying to
determine the correct way to pin it out so I can use this arrangement to
talk to the RS232 interface on the TNC-2.

    Any feedback would be appreciated.


                                                                Fred, WB4AEJ

----- Original Message ----- 
From: "Daron J. Wilson" <daron at wilson.org>
To: <fred at wb4aej.com>; "'TAPR APRS Mailing List'" <aprssig at lists.tapr.org>
Sent: Monday, March 13, 2006 2:37 PM
Subject: RE: [aprssig] RJ45/RS232 Again

> What's on the modular plug end of this?  I'm assuming your TNC is the
> DB25,
> assuming this is a blue cisco 8 pin cable with modular plugs on it, but
> is plugged into the other end of the cable?
> Oddly enough, 8 pin modular plugs and RS-232 implementation vary depending
> on the equipment.  I guess I missed where you were going with this to
> with..
> > -----Original Message-----
> > From: aprssig-bounces at lists.tapr.org [mailto:aprssig-
> > bounces at lists.tapr.org] On Behalf Of Fred Atkinson
> > Sent: Monday, March 13, 2006 11:24 AM
> > To: aprssig at lists.tapr.org
> > Subject: [aprssig] RJ45/RS232 Again
> >
> > Hello,
> >
> >       I've revised that drawing showing the correct color codes for ch
> > of the RJ45 leads.  You can view it at
> > http://paws.wcu.edu/fatkinson/APRS/RS232_RJ45.pdf.
> >
> >       I've connected a Cisco rollover cable to it and plugged it into my
> > TNC-2.  But I'm not getting any data from it.  I am reasonably confident
> > that the TNC-2 is working.
> >
> >       Any idea what is wrong here?
> >
> >       73,
> >
> >
> >
> >                                                        Fred, WB4AEJ
> >
> > _______________________________________________
> > aprssig mailing list
> > aprssig at lists.tapr.org
> > https://lists.tapr.org/cgi-bin/mailman/listinfo/aprssig

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