Cisco SCH-IO-EXT-8 Reference Manual page 7

If you connect dry contact closure devices, such as door switches, connect the switch between +12V
Note
(Power) and SIG (Signal).
Connect to the Contact Port
The Cisco I/O Extender provides four (4) contact ports for the pluggable terminal block provided.
See
Figure 5
+12V and GND are used to power the Motion Sensor. SIG and GND are used to detect the state of the
Note
Contact in the Motion Sensor.
Figure 6
OL-27368-01
Figure 5 through Figure 7
Contact Port for Voltage Source (e.g., Motion Sensor)
Contact for Dry Contact (e.g., Door Contact Sensor)
to learn how to connect the device to a contact port.
Cisco Smart+Connected I/O Extender Reference Guide
Connecting the Devices
7