Apcupsd's Support for USB UPSes
General
Apcupsd version 3.9.8 or later (development version to be released as
3.10.0) 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) or an
IOGear Serial to USB converter.
- Apcupsd version 3.9.8 or higher
- Version 2.4.5 or later of the Linux kernel
- Either 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. Please note that USB
enabled kernels are becoming more and more common
so you may not need to build your own.
- Or a pre-built kernel containing the USB patches such
as is available as an update for RedHat 7.1, or standard
in RedHat 7.2. Other vendors provide USB ready kernels
as well.
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.
Direct support for USB UPSes
The rest of this chapter concerns making apcupsd work
by connecting your USB enabled UPS directly to a USB port
on your Linux machine.
Please note if you have cable number 940-0127A (and possibly
940-0128A), your UPS will be connected to your serial port
as a standard serial UPS and the rest of this chapter will
not apply to your case.
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
USB Specific Information
The UPS has an internal set of timers and remaining capacity
counters, which it uses to determine when to shutdown. These are in
addition to the apcupsd counters BATTERYLEVEL and
MINUTES. As a consequence, apcupsd will shutdown on the first
limit that triggers (either an apcupsd limit, or a UPS limit).
The UPS internal
counter equivalent to BATTERYLEVEL can be found in the hid-ups report
as 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.
If you are technically inclined, you may want to look at the /proc file
system to see what devices are attached to your USB ports.
The most interesting information will be found by listing the
contents of /proc/bus/usb/devices. This information is
updated by the kernel whenever a device is plugged in or unplugged,
irrespective of whether apcupsd is running or not.
To interpret the
codes in this file, please see
http://www.linuxhq.com/kernel/v2.4/doc/usb/proc_usb_info.txt.html
As a reference, on my system, I have the following entry
for my Back-UPS 350 direct connected USB device:
T: Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=1.5 MxCh= 0
D: Ver= 1.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
P: Vendor=051d ProdID=0002 Rev= 1.00
S: Manufacturer=American Power Conversion
S: Product=Back-UPS 350 FW: 5.2.I USB FW: c1
S: SerialNumber=BB0115017954
C:* #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr= 30mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=00 Prot=00 Driver=hid
E: Ad=81(I) Atr=03(Int.) MxPS= 8 Ivl= 10ms
And for my IOgear that runs my serial SmartUPS 1000 (plugged into
a USB port):
T: Bus=01 Lev=01 Prnt=01 Port=01 Cnt=02 Dev#= 4 Spd=12 MxCh= 0
D: Ver= 1.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
P: Vendor=0557 ProdID=2008 Rev= 0.01
C:* #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=100mA
I: If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=serial
E: Ad=81(I) Atr=03(Int.) MxPS= 10 Ivl= 1ms
E: Ad=02(O) Atr=02(Bulk) MxPS= 64 Ivl= 0ms
E: Ad=83(I) Atr=02(Bulk) MxPS= 64 Ivl= 0ms
Note that the IOgear device is using the serial driver (the I: line)
while the Back-UPS 350 is using the hid driver.
Known Problems
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, version 3.9.4 does not release the old device (serial port) lock
file and create a new one. This is not too serious.
If you disconnect the UPS and plug in a different one or a
different model, it will continue to function properly, but
in apcupsd version 3.9.4 the static data
such as the UPS name, model, serial number, and firmware will not
be updated. Versions 3.9.6 and greater detect
the change and do a complete reinitialization of the UPS and so
do not have this problem.
Currently (as of 3.9.8) 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.
Discliamer
First, please rememeber this is beta software. It is not yet complete
and there are sure to be some problems. We would appreciate hearing
about your experiences.