This module is what connects the doors and lights to the system. It contains an IO module for connecting relays and signal voltage connections, and is controlled by the SOL controller software. Connection to the main computer is via serial cable. This means that the distance from the main computer is somewhat limited. Typically the main computer is installed physically in the same enclosure as the IO controller, but the main computer can, if needed, be installed outside the box. Recommended maximum distance between the IO controller and the computer is 5 meters.