http://qkpm2ov2rjhjkhfsftskqho77uj5rewd5y44unkf6cb7tdhaxwcvh2id.onion/books/apc/APCUPSD%20User%20Manual.html
Typically
these are located in /dev/hiddevN , /dev/usb/hiddevN or /dev/usb/hiddev/hiddevN (where N is a digit 0 thru 9). Some
distributions (some Debian releases, possibly others) do not
provides these device nodes for you, so you will have to make them
yourself.