[rescue] Cheap UPSs

[rescue at sunhelp.org]

On Sun, 8 Jul 2001, Joshua D. Boyd wrote:

> I've been putting off buying a UPS for a long time because I wanted to
> wait to get one that could tell the computer to turn itself off.  Well,

A hint: this is relatively easy to do even if your UPS provides no power
good/fail feedback.  All you need to do is to hook an old modem to one of
your serial lines, plug it into unprotected power, and initiate a shutdown
either when a status line changes or it doesn't respond to a periodic
probe.

> Well, I get it home, open it, and find that this cheap little unit comes
> with the software and serial cable to be able to shut down the computer
> connected to it.  Presumably it speaks the standard APC protocol and as
> such will work with Suns or SGIs.  This is really cool.

The vanilla "Back UPS" units are contact closure, and can only report
power good/power fail.  This is useful, but naturally not as useful as the
true serial protocol used by the Back UPS Pro (also squarewave) and Smart
UPS (sinewave).  Beats the heck out of no UPS, though.

-James