Apcupsd's Support for USB UPSes
General
Apcupsd version 3.9.4 or later (development version to be released as
3.10.1) provides direct support for USB UPSes on Linux systems.
To run apcupsd with a USB UPS, you need the following
things:
- A USB UPS (for example APC's BackUPS 350 CS)
- Apcupsd version 3.9.4 or higher
- Version 2.4.5 or later of the Linux kernel
- Alan Cox's patch to your kernel. If you have
kernel 2.4.5, you must have patch ac12 or
later. For later versions of the kernel, any
ac patch should do.
Connecting a Serial port UPS to a USB port
If you would like to free up your serial port and
connect your existing serial port UPS to a USB port,
it is possible if you have one of the later kernels.
You simply get a serial to USB adaptor that is supported
by the kernel, plug it in and make one minor change to
your apcupsd.conf file and away you go.
Thanks to Joe Acosta for this out to me.
The device that Joe and I are using is IOgear
guc232a USB 2 serial adaptor. There may be other adaptors
that work equally well. If you know of one, please let
us know.
At my site, running RedHat 7.1 with kernel 2.4.9-12,
I simply changed my /etc/apcupsd/apcupsd.conf
configuration line to be:
DEVICE /dev/ttyUSB0
Depending on whether or not you have hotplug working,
you may need to explicitly load the kernel modules
usbserial and
pl2303. In my case, this
was not necessary.
Getting and Building a Kernel
Please note that a number of Linux packagers are including
Alan Cox's patches in their standard releases. This is
true for RedHat 7.1 and 7.2 if you have the latest
kernel updates. As a consequence before getting and
building your own kernel, if you are already running
a 2.4.5 kernel or later, please check whether or not
it already has the necessary USB updates. This can
be done by creating the device files and running the
USB test program as described below.
For some very brief instructions on how to get and build your
kernel, see the Kernel Configuration
section of this manual. More information on configurating a kernel
can be found in the kernel-HOWTO do.
Making the Device Files
Once you have your kernel installed and working, you need to
define the hiddev device files. This can be done by invoking
the script in <apcupsd-src>/examples/make-hiddev, which does the
following:
#!/bin/sh
mkdir -p /dev/usb/hid
mknod /dev/usb/hid/hiddev0 c 180 96
mknod /dev/usb/hid/hiddev1 c 180 97
mknod /dev/usb/hid/hiddev2 c 180 98
mknod /dev/usb/hid/hiddev3 c 180 99
mknod /dev/usb/hid/hiddev4 c 180 100
mknod /dev/usb/hid/hiddev5 c 180 101
mknod /dev/usb/hid/hiddev6 c 180 102
mknod /dev/usb/hid/hiddev7 c 180 103
mknod /dev/usb/hid/hiddev8 c 180 104
mknod /dev/usb/hid/hiddev9 c 180 105
mknod /dev/usb/hid/hiddev10 c 180 106
mknod /dev/usb/hid/hiddev11 c 180 107
mknod /dev/usb/hid/hiddev12 c 180 108
mknod /dev/usb/hid/hiddev13 c 180 109
mknod /dev/usb/hid/hiddev14 c 180 110
mknod /dev/usb/hid/hiddev15 c 180 111
Installing the HIDDEV Header File
Once you have built the kernel, you must put
a copy of hiddev.h into /usr/include. Use the
following:
cd /usr/src<kernel-source-directory>/
cp include/linux/hiddev.h /usr/include/linux/
Building the Test Program
Next, we recommend that you build and run the
hid-ups test program. To build it enter:
cd <apcupsd-src>/examples
make hid-ups
There should be no errors.
Now assuming that everything has gone
well to this point and that you have connected your
USB UPS, enter:
./hid-ups
It should print a sample report of the information that
it has obtained from your UPS. CAUTION! Do not run two
copies of this program at the same time, or your kernel
will freeze.
The report that is printed should look very similar to the
report in <src>/hid-ups.rpt.
If the program reports that the device was not found
ensure that all the appropriate modules are loaded as described
in the Kernel Configuration
section of this manual, then unplug your UPS and plug it
back in. This should permit the kernel to recognize the
UPS.
Building and Installing apcupsd
If you have gotten this far successfully, the last step should
go fairly easily. You need a beta version 3.9.4 or later of
apcupsd. Follow the instructions in the Installation Chapter
of this manual, being sure to include the following options (in addition
to any others you need) on the ./configure line:
./configure \
--with-serial-dev=/dev/usb/hid/hiddev[0-9] \
--with-upstype=usb \
--with-upscable=usb \
--enable-pthreads \
--enable-usb
Discliamer
First, please rememeber this is beta software. It is not yet complete
and there are sure to be some problems. However, as of October 2001,
it has be successfully running with an APC BackUPS 350 CS for two and
a half months on kernel 2.4.5-ac12.
Known Bugs
If either you disconnect the UPS or it disconnects because of some
electrical problem, it will most certainly reconnect with a different
device number. Apcupsd will detect this and reconnect properly. However,
at the moment, it does not release the old device (serial port) lock
file and create a new one.
If you disconnect the UPS and plug in a different one or a
different model, it will continue to run, but the static data
such as the UPS name, model, serial number, and firmware will not
be updated. This will be corrected in a future version.
You should not run two USB UPSes on the same machine. If you do
and they both disconnect at the same time, apcupsd is very likely
to confuse the two due to the change in device names described above.
Currently (3.9.4) there is no code to power off the UPS. This will
be forthcoming in a subsequent release. In the mean time, the UPS will
normally power itself down one to two minutes after the machine is
shutdown.
The UPS has an internal set of timers and remaining capacity
counters, which it uses to determine when to shutdown. These are not
currently completely integrated with the equivalent apcupsd
counters (BATTERYLEVEL and MINUTES) basically because I (Kern) am
not sure what the "right" way to do it is. As a consequence,
apcupsd will shutdown on the first limit that triggers (either
an apcupsd limit, or the UPSes limits). The UPS internal
counter equivalent to BATTERYLEVEL can be found in the hid-ups report
and is RemainingCapacityLimit, which is typically factory set to 10 percent.
In addition, the Low Battery signal is normally given by the UPS when
less than 2 minutes of run time remain.
I've made some important changes to the master/slave code
on 3.9.3, and have just recently noticed that they sometimes disconnect
and cannot reconnect, so I recommend not to use versions
3.9.3 or earlier for master/slave configurations that are critical.
Hopefully this is fixed in apcupsd version 3.9.4.
I have also tested apcupsd on kernel version 2.4.7-ac1, and
it works fine. However, Samba NMB services failed to start on this kernel,
probably because I have an older Samba version. As a consequence, for the
moment, I have reverted to using kernel 2.4.5-ac12.
Version 3.9.3 only builds if USB support is enabled -- a problem with
#ifdefing that needs fixing.