The I/O module is used to connect sensors and relays to the enVigil system. Sensors are digital inputs to the I/O module from say, motion detectors or temperature sensors. Relays are digital outputs from the I/O module. Relays can be used for turning off/on lights or setting off a siren.

Each I/O module supports up to 4 sensors and 4 relays. Up to 8 such I/O modules can be daisy-chained to support 32 sensors and 32 relays.