Patriot UPS to Windows 2000 configuration |
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I rescued a Patriot UPS from the dumpster.
The only problem was a dead
battery. I found a battery that was the same size
and rating. After the battery was replaced the UPS
started working. This UPS has a "dumb"
serial interface. It uses the control lines on the
interface to indicate power loss and low battery.
Windows 2000 has a built-in UPS service. The problem was identifying which pin on the serial interface Windows was monitoring. I searched the web for serial UPS pinouts. I tried a few out on my Win2K box. |
Patriot model SPS450VA B |
Here is the cable pin out |
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UPS interface DB9 connector pin | PC serial port DB9 connector pin |
1 shutdown the UPS when this pin is held high for 5 seconds | 4 DTR - Held high to shut down the UPS when the computer shuts down |
3 normally open switch connects to GND when power fails | 8 CTS - When low issues an AC power loss warning |
4 UPS GND | 5 GND |
5 normally open switch connects to GND when UPS battery is low | 1 DCD - When low initiates computer shut-down |
The PC serial port signal RTS (pin 7) is held high. I used this pin to pull-up CTS (pin 8) and DCD(pin1). Connect a 10K ohm resistor from PC serial port RTS ( pin 7) to CTS ( pin 8). Connect another 10K ohm resistor from PC serial port RTS ( pin 7 ) to DCD (pin1). This will pull CTS and DCD high until the UPS closes one of the switches. I bought the 10K resistors and DB9 connectors, male for the UPS and female for the PC at RadioShack. The resistors are connected to the PC DB9 connector. These signal levels do not meet the RS232 design guidelines. It works on my PC, your mileage may vary | |
Schematic of the UPS cable
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Windows 2000 software configuration
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In the
control panel open Power Options,
click on the UPS tab. Next click
the Select Button.
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Choose Generic for the manufacturer, click on
Custom, select the com port the UPS is connected to, and then click the
Next button.
Choose the com-port which will connect to the UPS. Click the Next.
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Click the negative radio buttons for the
Power Fail/On Battery and the Low Battery signal polarity. Then click
the Finish button.
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Next click the Configure button.
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Configure the UPS software response as shown.
Then click OK.
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Finally Apply the changes by clicking the
Apply button. The power management software will begin
monitoring the UPS.
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