I have an APC connected to a master freenas device.
I have a desktop connected to a separate dumb ups with a battery that lasts up to 1hr.

i want to use upsmon slave on the desktop, to be triggered for a power failure by the freenas master,
to then shutdown after 20min if power has not been restored.

I have struggling to figure out the correct config for

can i do this without a heartbeat UPS? Can someone help with the correct config please.