APC UPS control system - Manual (Page 72)

Power Off (killpower) of UPS Does Not Work:
Currently (as of 3.10.6) the code to power off the UPS works only if you have
a Linux kernel version 2.4.22 or greater, or you have applied the patches in
the examples directory to your kernel.
apcupsd Cannot Reconnect After a Reboot:
If apcupsd does not connect to the USB port when you reboot, it is probably
the appropriate kernel modules are not getting loaded correctly.
You can check this by bringing up your system, fiddling around until you
get apcupsd to work with the UPS, then doing cat /proc/modules andnd
save the output some place. Then reboot your computer and before you do
anything else, do the cat /proc/modules again. Most likely you will find
some of the usb modules are missing in the second listing.
There are two solutions:
• Ensure that you have the hotplug program loaded. It should fix the
problem. This is a bit of magic, so we are not exactly sure how it
works. The rpm I (Kern) have loaded is: hotplug-2001 02 14-15
You might want to read the man page on hotplug, and it might be
necessary to cp /etc/hotplug/usb.rc /etc/init.d/hotplug to get
it fully working.
• You can explicitly force the appropriate usb modules to be loaded by
adding:
/sbin/modprobe <missing-module-name>
in the /etc/rc.d/init.d/apcupsd script just after the start) case (at
about line 17). This will force the modules to be loaded before apcupsd
is invoked.
Monitoring and Tuning your UPS
After you have verified that your UPS is working correctly, you will probably
want to query the state of its health occasionally. The tools apcupsd gives
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