UPS monitoring using RS-232 line
There is an industrial standard for using a serial port to monitor UPS systems (eg. APC !)
BD9 connector pinout
Pin 2 : Mains Fail 4 : Common 5 : Battery Low 6 : ShutdownThis is the connection to a DB9, you can obviously convert this to a DB25 connection !
The output of the UPS is Normally Open, going close for Fault Condition !
The Shutdown feature is a RS232 +level signal asserted from the Host PC for 1 sec to shut the UPS down....
This information was collected from UPS serial cable pinout discussion in sci.electronics.design newsgroup April 1997.
I have not tested this information so there is no guarantee on the correctness of this wiring.