[OmniOS-discuss] UPS serial non-standard, WHY?

[Warren Marts]

Serial ports have two wiring standards DTE (data Terminal equipment)
and DCE (data Communication equipment), with the data pins and transmit
enables swapped.

Connecting DTE to DCE you use a straight-through cable; here both are DTE
so you need a crossover or "null modem" cable.

On Thu, Dec 4, 2014 at 6:08 PM, Michael Mounteney <gate03 at landcroft.co.uk>
wrote:

> OK, not an OmniOS matter but as a lot of people here will be using
> UPSs, I hope it's alright.
>
> I made what is apparently the common but incorrect assumption that the
> serial monitoring port on the back of my APC 700 UPS had a standard
> serial pinout but for some reason the TxD and RxD are swapped.  Is this
> just some random brain-&*^# on the part of an android within APC, or is
> there some actual reason for it?
>
> Don't plug a standard serial cable into the UPS:  it instantly powers
> off.  No fooling.
>
> This is the first step in getting UPS software monitoring in place.  I
> presume that the software of choice is NUT?  I can't find it in a
> repo so I suppose it's a build-it-yourself job.
>
> Michael.
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