The UPSes from Inform are pretty decent and cheap. They even come with Linux, BSD and Unix drivers. The Linux ones – at least – don’t work, though. I bough a Guard LCD 1000 VA and played with it a little until I made it work with my Debian server.
The shipped drivers are garbage – however, the UPS works perfectly with Network UPS Tools (nut in Debian), with the driver megatec. Here is the magic to include in /etc/nut/ups.conf:
[InformGuardLCD] driver = megatec port = /dev/ttyS0 desc = "My UPS"
To check that it works, you should run upsdrvctl -DDDDD start and watch what happens. You should also try to plug out the UPS from the power socket to force it to go to batteries.
If everything is ok, the rest of the config is pretty straightforward, nut has working samples. After you start the daemons, you can check the UPS status with upsc InformGuardLCD.
Enjoy 
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What is the NUT version?
Becouse i try 2.0.4-4_i386.deb in debian etch, and your methot is not working to me..
Trully.
Alfonz
I am using nut version 2.2.2.-6. Maybe you should upgrade?
Yes, i need upgrade… but 2.2 NUT is’t stable in Etch…and i tired to pack myself and find dependencies…(udev etc.)
Thanks a lot, and have good day.
A.
Hi. Can you help me with cable pinout? I don’t have the cable and i can’t find a schematic on net.
Thanks
Hi Dimitris, it’s a standard serial cable.