I want to say that there was some freeware utility, perhaps on the DECUS tapes throughout
the years, that offered very basic UPS monitoring. If I remember correctly, a UPS
that's having a power-fault would drop DTE or something like that, allowing a program
to monitor the serial port for a hangup, and then do whatever (presumably start a
countdown before taking action to see if DTE is raised again).
I don't know whether the current models do anything that basic any longer.
--Marc