[rescue] e4500 serial wiring

Dave K davek08054 at gmail.com
Thu Jul 12 09:34:58 CDT 2007

On 7/12/07, Sridhar Ayengar <ploopster at gmail.com> wrote:
> Dimitar Vasilev wrote:
> > ... null-terminal cable ... null-modem [cable] ...
> Excuse my ignorance, but what is the difference?

I don't remember the details right now, but some where in the past I
needed to interconnect two DCE devices, and needed a very specific
"null terminal" configuration to do that.

In my mind a "null modem" cable is for interconnecting DTEs, and a
"null terminal" is for interconnecting DCEs, contrary to what "other"
people may call them.

The real difference is, of course, in the way the control signals are
handled, and whether they are actually being used for anything.  I
think in my example the DCEs were using half-duplex signalling, in the
manner of old 202 and 208 modems, and may even have been synchronous,
requiring clock signal handling.

Dave K
Unix Systems & Network Administrator
Mount Laurel NJ

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