TrueNAS supports monitoring UPS' using the open source Network UPS Tool (aka NUT). While they have done a good job of automating discovery, sometimes it is difficult to figure out which device is which when a UPS is plugged into a USB port.

The command

usbconfig

is your friend here. In this real life case, I found the Cyberpower PR1500 plugged in at ugen0.4.

ugen0.4: <CyberPower Systems PR1500LCDRTXL2U> at usbus0, cfg=0 md=HOST spd=LOW (1.5Mbps) pwr=ON (50mA)

It is on bus 0, port 4, so look for the direct link to that. It will either be called ugen* or uhid* in /dev

ls -ablph /dev/ugen* ; ls -ablph /dev/uhid*

This shows all entries named ugen* or uhid*, with the link that it actually points to.

lrwxr-xr-x  1 root  wheel     9B Nov 18 17:55 /dev/ugen0.4 -> usb/0.4.0

Services, then Actions for UPS

 Identifier: anything you want
 UPS Mode: Master
 Driver: find something close. Fro my PR1500, I used s PR6000
 Port: auto
 Shutdow: UPS goes on battery
 Shutdown Timer: 600 (seconds, or 10 minutes)
 

Start and see if it works. Then, you can view the UPS with

upsc ups

where 'ups' is the name you chose as Identifier.

If it all appears to be working, put a check for Automatically start. NOTE: you can view some stats on the UPS under Reporting.

Track CPU Temperature (by core) sysctl -a | grep temperature | grep cpu

Power

ipmitool sensor | grep 'Power Meter' | cut -d'|' -f2 ; upsc ups | egrep 'ups.load|ups.realpower.nominal'