APC SU1400XLT User Manual download pdf (Page 73)

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.

Testing Serial-Line UPSes

If you have a serial-line UPS, there are some tests you should run before the general ones described in

the Testing Apcupsd section.

To test your computer's connection with a serial-line UPS, you first need to establish that the serial line is

functioning, and then that the UPS is responding to commands. This can be a bit tricky, especially with a

dumb voltage-signalling interface, because it is completely quiescent when there are no commands being

passed, and the command repertoire doesn't include any self-tests.

Because it is easy to configure a serial cable incorrectly in such a way as to cause premature shutdowns

of the UPS power, we strongly recommend, especially for voltage- signaling (dumb) UPSes, that you do

most of the initial testing with your computer plugged into the wall rather than your UPS. Thus if the UPS

power is suddenly shut off, your computer will continue to run. We also recommend using safe-apccontrol

as described below, until you are sure that the signaling is correct.

Also note that if you launch the execution of apcupsd while your voltage-signaling UPS is on battery

power, it is very likely that your UPS will immediately shut off the power. This is due to the initialization of

the serial port line signals, which often looks to the UPS like a shutdown command.

Finally, double-check the state of your cabling and UPS indicator lights frequently during testing. For

voltage-signaling UPSes, apcupsd is not currently able to detect whether or not the serial cable is

connected. In addition, some simple signaling UPSes with certain cable combinations are not able to

detect the low battery condition. For more details please see Voltage Signalling Features Supported by

Apcupsd for Various Cables.

Establishing Serial Port Connection

Once you have compiled, installed, and invoked apcupsd, you should wait to allow apcupsd to configure

itself and establish contact with the UPS.

If you see a message similar to the following about 30 seconds after starting apcupsd...

apcupsd FATAL ERROR in apcserial.c at line 156

PANIC! Cannot communicate with UPS via serial port.

it means that apcupsd tried for about 30 seconds to establish contact with the UPS via the serial port, but

was unable to do so. Before continuing, you must correct this problem. Some of the possible sources of

the problem are:

• You have not configured the correct serial port name on the DEVICE directive in your apcupsd

configuration file.

• The serial port that you have chosen has logins enabled. You must disable logins on that port,

otherwise, the system prevents apcupsd from using it. Normally, the file /etc/inittab specifies the

ports for which a getty process is started (on Sun machines, the serial port program equivalent to

getty is called ttymon). You must disable this for the port that you wish to use.

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APC SU1400XLT User Manual Page 73