[Soekris] Second Serial Port as RJ45?

Bernd Walter soekris-tech at cicely.de
Tue Nov 26 21:01:03 UTC 2002


On Tue, Nov 26, 2002 at 02:56:18PM -0500, Henry Spencer wrote:
> > > Put dual DIN connectors on the box instead -- achieves the goal of reducing
> > > real estate, but according to a standard.
> 
> The mini-DIN connectors have a couple of problems, alas.  For one thing,
> the usual ones have no mechanical locking, which is a serious defect in
> some operating environments.  For another, to do nonstandard cabling --
> which is far from rare in the serial world -- you pretty much have to use
> an adapter to convert them to some more tinker-friendly connector first. 

Ack - mini-DIN is not an option.
And you can't expect any field service to have those adapters in their
toolbox.

> RJ-45 would be a much better choice, if only people followed a single
> standard.  (Any single standard; even the EIA standard that everyone
> ignores would be better than each device being different.)

The problem is that you don't get all wires on an RJ45.
But for console I only need 3 wire and all pinouts, that are used today,
agree on those.
For all other situations there is no real problem to build custom
cables by need.

> > The Nemith system admin book has a scheme from Berkeley to wire RJ-45
> > well.  A straight cable is DTE-DCE, a reversed cable is a null modem!
> 
> An overrated virtue, especially if you prefer to use Cat5 cabling rather
> than having separate cable types for network and serial.  (A Cat5 crossover
> is not the same as a reversed flat cable.)

I very much prefer using flat cable (ISDN style) for RJ45 serials.
It cheap cable and you can easily setup in the exact length you need.
Exact length is a very fine feature in high density racks.
And with those cables is easiest to setup such a reversed cable than any
other pinout.

-- 
B.Walter                   BWCT                http://www.bwct.de
ticso at bwct.de                                  info at bwct.de




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