Honeywell Silent Knight IFP-2000 Module 3 Installation Manual page 52

Flexput™ I/O Circuits Flexput
The polarity of the Flexput™ terminals differs
depending on whether the circuit is programmed
as an input or an output circuit
Input circuit
Detector or normally open contact
X terminal is negative X terminal is negative
O terminal is positive
Output circuit
Aux power or NAC
X terminal is positive
O terminal is negative
™ I/O Circuits