Making APC 500 Back UPS (basic) work with FreeBSD

Paul Mather paul at
Tue Feb 21 11:20:46 PST 2006

Chuck Swiger <cswiger at> wrote:

> Donald J. O'Neill wrote:
> > On Tuesday 21 February 2006 08:26, Chuck Swiger wrote:
> [ ... ]
> >> No.  If your UPS isn't smart and does not have an external USB or
> >> serial port, apcupsd has nothing to work with.
> > 
> > As best I can tell from the OP's description, and the APC website,
> they 
> > all have a UPS port. Go from there.
> All of the new Smart-UPS APC models that they are selling now have USB
> ports.
> There are plenty of older models around in the channel, and there is
> the entire
> Back-UPS model line that are not "smart", and thus have no
> monitoring/shutdown
> capabilities.  See the Subject: header...

For my home, I bought a Back-UPS Pro 1100 that was inexpensive.  It came
with a 940-0020C serial cable.  Unfortunately, this only supports simple
signalling, so you can't monitor the UPS for its vital statistics
regarding percentage battery life left, etc.  I guess that's why it was
inexpensive.  But, it does work with apcupsd, and you do get
notification of power loss and even a critical power low warning signal
you can use to trigger shutdown of your machines.  It has worked well
for me.

I don't know if your statement about the "entire Back-UPS model line"
also encompassed the Back-UPS Pro models.  I just wanted to say there
was at least one Back-UPS Pro UPS that did support monitoring/shutdown
capabilities, albeit the restricted simple signalling type.

I agree that if the OPs UPS doesn't have any type of data connection to
a host computer then it won't be possible to get it to interface with
apcupsd.  However, I haven't heard of an APC UPS that didn't come with
some kind of data cable, so it would be useful if the OP posted the
precise model: there are several in the Back-UPS 500 line, such as the
Back-UPS 500; Back-UPS CS 500; Back-UPS ES 500; etc.  All of them
support either a serial or USB cable.  (The CS supports both.)


e-mail: paul at

"Without music to decorate it, time is just a bunch of boring production
 deadlines or dates by which bills must be paid."
        --- Frank Vincent Zappa

More information about the freebsd-questions mailing list