[Tfug] Yet another poser

[Bexley Hall]

--- johngalt1 <johngalt1 at uswest.net> wrote:

> My junk box has a number of serial adapters also.
> But this is far from comprehensive. There are just
> too many possibilities.

Yup.  I stick to the mainstream ones and add oddballs
as the need arises (i.e. if I am going to *have* to
build a special cable, I might as well make it as
a "widget", instead!).

But, I've had to deal with a lot of oddball "devices"
over the years that bastardize the "RS-232" interface
(about the only thing they can claim as conforming
to the "Standard" is the connector shell!  :< ).
Things with exotic voltages on pins, current loop
signals mixed with EIA232 levels, nonstandard use
of signals (e.g., pacing via RLSD!), etc.

> Lately, I have been rolling my own. I am fond of
> those DB9 or DB25 shells with RJ45 jacks molded 
> in. If the device doesn't require handshaking, I
> don't bother. If transmit, 
> receive and ground doesn't work, I put one of those
> passthroughs with the 
> LEDs on each side and the device may give a clue
> what it wants. Cisco and 
> others place the center conductors (4,5) as ground.
> Then, transmit and 
> recieve share the next conductors out (3,6). If I
> need to change between DTE 
> and DCE, I use an RJ45 cable that has a twist
> instead of straight through. 

This is where I rely on widgets.  Cables are just
extension cords.  :>

> Beyond that, it's not well thought out.
> 
> Regarding the Ethernet crossover issue, I pulled out
> a factory made cable 
> bought at Graybar. It omits pairs other than the
> transmit and receive pairs. 
> I put an "X" tag or sharpie mark on such cables.

Hmmm... an off-list comment from a friend shows
the extra conductors as present.  :-(


       
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