The F900-821 Input-Output Module is an addressable device that provides a Style “B” (Class B) or Style “D” (Class A) initiating device circuit to monitor dry contact initiating devices. The module’s output provides a Form “C” dry contact for control or override functions. The module features a LED status indicator that blinks during communication. The LED can be programmed to come on steady when the initiating device circuit goes into alarm or the output is activated.