APC UPS control system - Manual (Page 64)

If you see a message to the effect of:
attach_shmarea: shared memory version mismatch (or UPS not yet ready to report)
or if all the displayed values are zero, you have not waited long enough.
Wait a bit longer and then re-execute the apcaccess status command.
If you see a message to the effect of:
APCACCESS FATAL ERROR in apcaccess.c at line 336
tcp_open: cannot connect to server localhost on port 3551.
It means that you have probably not enabled the Network Information
Server in your configuration file for apcaccess to work. This is done by
setting:
NETSERVER on
NISPORT 3551
in your apcupsd.conf file.
Communications Test
At this point, you should ensure that apcupsd is handling the connection to
the UPS correctly. This test assumes you have a UPS that speaks apcsmart
protocol, over either USB or a serial port. If you have an old-style voltage-
signaling UPS, please skip to the next section (Simulated Power Fail Test).
When apcupsd detects a problem, it generates an EVENT, which consists
of sending a message to the system log then invoking the apccontrol script
(normally in /etc/acpupsd/apccontrol) to handle the event.
In order to create an event, remove the serial port plug from the back of
your computer or from the back of the UPS. Within 6 seconds, apcupsd
should detect the lack of serial port communications and broadcast a wall
message indicating that the serial port communications was lost:
Warning communications lost with UPS lost.
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