We'll describe the possible values here, because they're a good way to explain your UPS's single most important interface property: the kind of protocol it uses to talk with its computer.
The 'apcsmart' protocol uses an RS232 serial connection to pass commands back and forth in a primitive language resembling modem-control codes. Originally introduced for Smart-UPS models (thus the name 'apcsmart'), this class of UPS is in decline, rapidly being replaced in APC's product line by USB and MODBUS UPSes.
This manual is divided into parts which increase in technical depth as they go.
If you have just bought a state-of-the-art smart UPS with a USB or Ethernet interface, and you are running a current version of Red Hat or SUSE Linux, then apcupsd is very nearly plug-and-play and you will have to read only the Basic User's Guide.
If your operating system is older, or if you have an old-fashioned serial-line UPS, you'll have to read about serial installation (see Installation: Serial-Line UPSes).
If you need more details about administration for unusual situations (such as a master/slave or multi-UPS setup) you'll need to read the sections on those topics as well.
The the authors, contributors and editors, expressly disclaim all and any liability and responsibility to any person, whether a reader of the manual or not, in respect of anything, and of the consequences of anything, done or omitted to be done by any such person in reliance, whether wholly or partially, on the whole or any part of the contents of the manual.
Without limiting the generality of the above, no author, contributor or editor shall have any responsibility for any act or omission of any other author, contributor or editor.
MODBUS (see below) is required in order to access the advanced data.
The following is a help guide to the steps needed to get apcupsd set up and running as painlessly as possible.
apcupsd supports many UNIX-like operating systems as well as several variants of Windows.
This is the manual for apcupsd, a daemon for communicating with UPSes (Uninterruptible Power Supplies) made by American Power Conversion Corporation (APC).
If you have an APC-made UPS, whether sold under the APC nameplate or OEMed (for example, the HP Power Trust 2997A), and you want you get it working with a computer running Linux, Unix, or Windows, you are reading the right document.