The ST-IO is a Cresnet expansion module that provides eight low-voltage relay outputs and four digital/analog input ports. Typical applications include control of lighting, screens, drapes, and more. In "closure" mode, each input port will sense a contact closure signal from a door switch, motion sensor, etc., and can also accept analog 0-24 Volt DC signals when in "voltage" mode. The ST-IO may be used to provide a low-voltage control interface at a remote location, or may be rack mounted in the central equipment cabinet to EX and the number of control system ports (ST-RMK rack mount kit sold separately). Communication with the control system is via a single Cresnet connection.