Users Manual & Installation Guide
PV- 5127: Power supply module with UPS
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00h: SOFT_OFF (first half of 2-second delay)
FEh: SOFT_ON
FFh: SOFT_OFF (second half of 2-second delay), or SOFT_TEMPBAD
Other values: SOFT_DELAY, delayed shutdown in progress. value = remaining seconds until
SOFT_OFF
Software normally won’t read the values 00h and FFh since the 5V+12V is off at this time. Writing
00h will turn off power immediately, and it will stay off for at least two seconds. You shouldn’t
write FFh since this will turn power off for only one second, and this might not be enough for a
CPU to reboot cleanly. Writing FEh will cancel a delayed shutdown in progress. Writing other
values will initiate (or modify) a delayed shutdown, with the value being the number of seconds
until SOFT_OFF.
Software compatibility
Windows NT 4.0: The PV-5127 RS232 interface is directly compatible with the Windows NT 4.0
UPS service, using the CDB-9F cable. It can monitor the three statuses (Normal, Mains alarm,
Critical alarm), and use the RS232 Shutdown signal to power off.
Windows 2000 and XP: The UPS service in these operating systems can monitor the three statuses
(Normal, Mains alarm, Critical alarm) through RS232, but it cannot power off the PV-5127 with the
Shutdown signal. This is because the UPS service is terminated during shutdown, so it cannot
activate the Shutdown signal when shutdown is complete.
To power off the PV-5127 after a shutdown under Windows 2000 and XP, you must use either the
PS_ON signal with an ATX compatible CPU, or the PC/104 interface. Using the PS_ON signal
ensures that power is turned off exactly when the operating system has finished shutting down.
The PC/104 interface is used by the PV-5127 UPS minidriver available at http://www.micro-
technic.com/pv5127/. This method does not use an RS232 port or cable.
Linux: Several UPS monitoring daemons exist which use the “simple” or “dumb” signalling
protocol on a serial port. Examples are:
• apcupsd (http://www2.apcupsd.com): When using the CDB-9F cable, you should specify
UPSCABLE 940-0020B.
• Network UPS Tools (http://www.networkupstools.org): When using the CDB-9F cable, you
should specify genericups upstype=2.
• Other daemons: Make sure that you use the right handshake signals since no single standard
exists for which handshake are used for which function, and adapt either the software
configuration or the cable accordingly.
With some UPS hardware, you can experience a “deadlock” problem if mains power comes back
after the UPS monitoring software has decided to shut down the operating system. This happens if
the UPS monitoring software is unable to turn off power after the operating system has finished
shutting down, because mains power has come back. This cannot happen with the PV-5127
because it always turns off power for at least two seconds after a power-off command through
RS232 or PC/104, even if mains power is present.