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1. Introduction

This HOWTO covers connecting a UPS to a computer running Linux. The idea is to connect the two in such a way that Linux can shutdown cleanly when the power goes out, and before the UPS's battery gives out.

This includes pointing out the existence of software packages which aid in establishing such communications, and detailing exactly how such communications are carried out. The latter often is unnecessary if you can find a software package that's already been configured for your UPS. Otherwise, you'll have to read on.

To a large extent this document is even more redundant than when I originally wrote it three years ago. All the basic information has always been contained in the powerd man page that comes with the SysVinit package. Whereas three years ago one could commonly find Linux distributions which didn't even include this man page, I don't believe this is the case any longer.

Furthermore, when I first wrote this Howto, there was no software other than powerd.c for Linux/UPS communications and control. Today there are quite afew UPS control packages available in Sunsite's UPS directory.

None the less, I'm continuing to maintain the UPS Howto. Why bother? Well,

1.1 Contributors

I am forever indebted to those from whom I've received help, suggestions, and UPS specific data. The list includes:

Note that email addresses appearing below as excerpts from email messages can be out of date. The above is probably out of date too, but some of it's more recent than what's below.

Also, many apologies to anyone whom I've failed to note in this list. Please email me and I'll add you.

1.2 Important disclaimer

I really can't guarantee that any of this will work for you. Connecting a UPS to a computer can be a tricky business. One or the other or both might burn out, blow up, catch fire, or start World War Three. Furthermore, I only have direct experience with the Advice 1200 A UPS, and a 5kva Best Ferrups, and I didn't have to make a cable. So, BE CAREFUL. GATHER ALL INFORMATION YOU CAN ON YOUR UPS. THINK FIRST. DON'T IMPLICITLY TRUST ANYTHING YOU READ HERE OR ANYWHERE ELSE.

On the other hand, I managed to get everything working with my UPSs, without much information from the manufacturer, and without blowing anything up, so it is possible.

1.3 Other documents

This document does not cover the general features and capabilities of UPSs. For that type of information, you might turn to The UPS FAQ. It can also be found at It is maintained by Nick Christenson ( ), but seems to have last been updated in 1995. In email to him, he'd like that you put UPS or UPS FAQ or something along these lines in the Subject line of the message.

There're also more and more UPS manufactures sprouting up on the net. Some of them actually supply useful information on their web sites. A convenient list of UPS manufacturers' web sites is available at The UPS Directory. Said site also has a UPS FAQ.

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