Users Manual & Installation Guide
PV- 5127:
Power supply module with UPS
Page 17 of 31
PC/104 interface
The PV-5127 has a software interface where the CPU can read status information and perform a
power-off through the PC/104 bus. The power-off can be delayed up to 253 seconds, so that the
UPS monitoring can start the delayed power-off, then start a shutdown of the operating system, and
the actual power-off happens after the operating system has finished shutting down.
When a delayed power-off has been initiated, the software can later cancel or modify it. This
means that the delayed power-off can be used as a software watchdog: If the software e.g. once
every second starts a power-off specifying a delay of 10 seconds, the system is continuously kept
on. If, because of a software error, the refreshing of the delayed power-off stops, the PV-5127 will
power off the system in 10 seconds. If mains is present and the system temperature is OK, the PV-
5127 will turn on again two seconds later, ensuring a clean reboot.
This interface is used by the PV-5127 UPS minidriver for Windows 2000/XP. You only need the
following information if you want to write your own UPS monitoring or watchdog software.
To the CPU, the PV-5127 appears as a fixed block of eight I/O addresses at 250h-257h. It doesn’t
use any memory addresses, IRQs, or DMA channels.
SIGNATURE (port 250h, read only):
This port always reads as 37h. Software can read this register to verify the presence of a PV-5127
adapter.
STATUS (port 251h, read only):
0000bmss
This port contains the following read-only status information bits.
ss (STATUS bit 1-0): System temperature, according to the internal or external system temperature
sensor.
ss=00:
Too cold
ss=01:
Cool
ss=10:
Warm
ss=11:
Too hot
m (STATUS bit 2): Mains present.
m=0:
Mains voltage not present
, running on battery
m=1:
Mains voltage present
Address
Read/write Function
250h
read only
SIGNATURE
251h
read only
STATUS
252h
read only
BAT_STATUS
253h
read only
RS232_STATUS
254h
read/write
SHUTDOWN
255h
-
Reserved
256h
-
Reserved
257h
-
Reserved
