On Sep 6, 11:27, Curt Vendel wrote:
> You can use any straight through RJ45 cable, standard Cat5 is fine as
well.
> Radio Shack sells do it yourself connector kits with rj45 on the plastic
> hood and you just plug in the appropriate cables to the connector, for
the
> DB-9/DE-9 wire as follows:
>
> 2 - yellow
> 3 - black
> 4 - orange
> 5 - green & red
> 6 - brown
> 7 - blue
> 9 - white
>
> If you run into problems and can't get it going, just let me know, I've
made
> like a doz of them as I use them all the time on various cisco devices.
That's somewhat Cisco-specific, if those are the standard colours. The
standard colours for 8-way flat cable (in order in the cable) are
1 grey (some cables use white)
2 orange
3 black
4 red
5 green
6 yellow
7 blue
8 brown
However, that's not always used in pre-made sockets. I have three
different ones on the desk beside me. One goes blue, orange, black, red,
green, yellow, brown, white, for example. That would give you the
following pinout:
RJ45 pin DE9 pin signal
white 8 9 Ring Indicator
brown 7 6 Data Set Ready
yellow 6 2 Transmit Data
green 5 5 Signal Ground
red 4 5 Signal Ground
black 3 3 Receive Data
orange 2 4 Data Terminal Ready
blue 1 7 Request To Send
It would be much more usual to pair RTS with CTS (DE9 pin 8).
One of the most common ways to wire an RJ45 for serial, are to wire the
centre pair both to ground, with TxD on one side and RxD on the other.
That way, if you turn the cable upside down you (as in a normal flat
cable, one end is wired opposite to the other) you cross over RxD and TxD
without losing the ground. TxD is pin 3 on a PC-compatible DE9 serial
port, RxD is 2, and signal ground is pin 5, so that's fine. In a flat
cable, the pairs start from the centre two wires, and work outwards to both
sides, ending up with the 4th pair being the two outermost wires.
But most systems that use this scheme put DTR and DSR (or occasionally DCD)
on the next wires out from the centre (3rd pair), and DTR is on DE9 pin 4
(orange, OK) and DSR on pin 6 (brown, no I don't think so) and DCD on pin 1
(which Cisco obvioously doesn't use). The reason for putting DTR and DSR
(or DCD) on the next two wires is again for the crossover effect. That's
what DEC and several other companies do.
Similarly, some systems put RTS and CTS on the outermost two wires.
Looks like Cisco are using a non-standard colour order (or your RS adaptor
is) but otherwise following one of the common wirings for flat cable
(except for RI and RTS!).
Of course, lots of people use UTP instead of flat cable. Then one way to
start off is to put TxD and corresponding ground on pins 1+2 (which is one
pair) and RxD and corresponding ground on the next pair (3+6). That way,a
normal UTP crossover cable (one end wired to TIA 568A and the other to
568B) crosses things over correctly. That leaves 4+5 and 7+8 for other
signals, usually unused but sometimes DTR+DSR and RTS+CTS (to keep each
pair of signals in a single pair of wires, but it makes crossover cables
"interesting"). DEC do it like that, they put 1 and 3 on the RJ45 to
ground (actually Tx- and Rx-), TxD and RxD on 2 and 6, DTR and DSR on 7 and
8. Sun do a similar thing (but not quite the same).
There is *no* standard for this, and I've found at least three common (and
largely incompatible) wiring schemes, and several more obscure ones
(Cabletron, Xylogics, ...)
--
Pete Peter Turnbull
Network Manager
University of York
Received on Wed Feb 06 2002 - 15:04:23 GMT