Cyber power CP1000PFCLCD is supported in the version of NUT used in freenas, and is included in the UPS dropdown menu. However, doing a test of the UPS at the expected point of shutdown the console message responds:
FreeNAS upssched-cmd: Shutdown not initiated as ups.status indicates CP1000 is ONLINE (OL)
ups.status is indicating both before and after the issuing of this message that the UPS is "OB DISCHRG". Clearly stating that the UPS is running off battery and discharging.
Following this command, plugging in the UPS initates an immediate shutdown of the computer without a safe shutdown of freenas.
Some additional comments can be found here, starting at post #21.