Input and Output Connections
AC-225x-B Series Hardware Installation and User Manual 23
4.1.6 Normally Closed Supervised Double Resistor Input
Connection
Connect a 2.2 kΩ resistor in series to the input switch contacts.
Connect an 8.2 kΩ resistor parallel to the input switch contacts.
Normally Closed Supervised Input has 3 states:
▪ Switch Closed – Normal State:
Loop resistance = 2.2 kΩ
▪ Switch Open – Abnormal State:
Loop resistance = 10.4 kΩ
▪ Open circuit (Infinite loop resistance) or short circuit (0 resistance) across
input terminals – Trouble State
Figure 15: Normally Closed Supervised Input Connection (Double Resistor)
4.2 Inputs Description
4.2.1 Request-to-Exit (REX) Button Input
Use the REX input to open a door directly. Typically, the REX input is connected to
a Normally Open push button that is located inside the premises. The push button
is generally located in an easy-to-access position and opens a door without reading
a proximity card or PIN code.
4.2.2 Door Monitor Input
The Door Monitor input typically connects to a Normally Closed door sensing
micro-switch for door status monitoring. Using Door Monitor enables many