Re: gEDA-user: OT: D-sub pin-shorter / pin-breaker?

[der Mouse <mouse@xxxxxxxxxxxxxxxxxxxx>]

> I'm working on a project that cables several boxes together, which
> signal each other using "dry contacts"; i.e. by closing or opening a
> pair of wires.  The interconnect cables all use D-sub connectors
> (DB9, DB15, and DB25).

ITYPM DE9 and DA15; I've never seen a 9- or 15-position connector in a
DB shell (but I've often seen DE9 and DA15 miscalled DB9 and DB15).
But that aside,

> For testing, I need to inject some hardware faults of the kind where
> such a pair of wires fails closed or fails open.  I am looking for a
> little device that has, say, a DB15 male on one end and a DB15 female
> on the other normally connected straight through [and which can
> create such faults]

I've seen these for DB25, in the form of connectors brought out to what
I might call "1-pin sockets" into which one can plug jumper wires.  (A
batch of jumper wires typically comes with them, but pretty much any
moderately-fine-gauge wire works fine, such as the stuff from spare
Cat5 or Cat3 cable.)  The ones I've seen generally hardwire pin 1
connected through, because they're designed for serial-line use, but I
suspect that's not universal (and even if it is, you can interpose
adapters which permute the pins to put the pairs on, say, 2&3, 4&5,
etc).  I've never seen them for DE9 or DA15, but I imagine they exist.
If nothing else, it would border on trivial to wire up adapters with a
DE9 (or DA15) on one end and a DB25 on the other, so you can use the
DB25 version of the thing.

Or, you can just solder wires to a connector and plug them into a
bog-standard solderless breadboard.  (I'm assuming your signals are
slow enough that rat's-nest wiring isn't going to produce unacceptable
levels of crosstalk.)

These suggestions do assume you don't mind manually moving wires to
induce "faults".  If that needs to be automated, you may need to wire
them up to relays or some such.

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