Multiple Signal Fiber Optic Modems combine multiple system communications signals and converts them to fiber optic communications for transmission via a single, full duplex fiber optic cable connection that simplifies field wiring and increases transmission distances. Communications can be sent individually or combined. Application: For direct mounting onto a 4100ES/4100U expansion bay; Fiber Modems are required to be ordered in pairs (Left-Port Fiber Modems communicate only to Right-Port Fiber Modems)