Pyronix PIR wiring

[studentspark]

Could some one please explain whats happening here.
Its the Pyronix V10.

Im trying to understand alarm wiring.
Im don't understanding the circuit, the two resistors share a common connection
How does the loop work.
I hope that makes some sense
Thanks

 

[secureiam]

Think of the common as a point to measure from for each zone, so you measure from common to zone 1 and from common to zone 2. In which case you are looking at two separate loops.