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Installation: Serial-Line UPSes
Overview of Serial-Interface UPSes
If you have a UPS that communicates via serial port, you need to do two
things before you can even think about configuring the software. First, you
need to figure out whether it’s a dumb (voltage-signalling) UPS or speaks
the apcsmart protocol (see this discussion (see upstypes)). Second, if you
have an interface cable from APC, you need to figure out what kind it is.
If you don’t have such a cable, you need to build one. A straight-through
serial cable won’t work (see crazy).
According to Bill Marr the Belkin F5U109, also sold as F5U409 also works
with apcupsd for kernel versions 2.4.25 or higher and kernels 2.6.1 and
higher. These newer kernels are needed to have the patch that makes the
mct
u232 (Magic Control Technology) module and other adapters work with
RS-232 devices that do not assert the CTS signal.
Connecting a Serial-Line UPS to a USB Port
By using a special adaptor, you can connect your serial-line 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 adapter that is supported by the
kernel, plug it in and make one minor change to your apcupsd.conf file and
away you go. (Kern adds: Thanks to Joe Acosta for pointing this out to
me.)
The device that Joe Acosta and Kern are using is IOgear GUC232A USB
2 serial adapter. Bill Marr informs us that it also works with a Back-UPS
Pro 650 and the 940-0095B cable.
At Kern’s site, running Red Hat 7.1 with kernel 2.4.9-12, he simply changed
his /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 Kern’s case,
this was not necessary.
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