home owner needs advice

[CalT <calT@xxxxxxxxxxxxxxx>]

I have some Optex Annunciators protecting my rear laundry room
entrances.

http://www.optexamerica.com/security-products/rctd-20u

I need a siren to be tripped by this to scare any burglar or whomever
away before they continue on into my home.  In the Optex manual it
says:

"Terminal Connection:  Any device with a zero voltage input terminal
can be connected to this terminal.  This may include electronic locks,
emergency sounding devices, and automatic reporting equipment."

I do not understand the term "zero voltage input terminal".

When the Optex triggers on movement it senses and the NO terminals
close, how can they activate any relay or whatever if the terminals
cannot have a voltage applied or current running through them?

Somewhere I am not understanding something here.  I am used to hooking
up relays in my screwing around over the years, but this has me
baffled.