The Protege Single Input Expander provides the interface of an additional input for monitoring and automation in the Protege integrated access control, security and building automation system. With an input which can be used for extended monitoring functionality, the Single Input Expander provides extensive hardware advancements that allow flexible input programming and configuration. The Single Input Expander is designed to allow the simple upgrade of systems where motion detectors, smoke detectors, and any other dry contact input devices have been deployed using a four-wire bus topology. Using the RS-485 module network, the expander is ideal for schools and larger sites where long cable runs and complex wiring routes are present.