APC 900XL Power Supply User Manual


 
Page 27
6.0 UPS Monitoring
6.4 Computer interface port
The computer interface port is diagramed below for your reference. Those with technical
abilities wishing to use this port in a special application should be aware of the following
limitations and capabilities of the interface.
Outputs at pins 3, 5 and 6 are actually open collector outputs which must be pulled up
to a common referenced supply no greater than +40 Vdc. The transistors are capable of
a maximum non-inductive load of 25 mAdc. Use only Pin 4 as the common.
The output at Pin 2 will generate a LO to HI RS-232 level upon transfer of the output
load to power derived from the UPS’s battery. The pin is normally at a LO RS-232 level.
The UPS will shut down when a HI RS-232 level, sustained for 4.5 s, is applied to Pin
1. The UPS responds to this signal, following a delay, only during mains failures (load is
operating from the UPS’s internal power source).
An unregulated +24 Vdc appears at Pin 8 of the interface port whenever the UPS is
powered. The supply is limited to 40 mAdc maximum.