MultiCom 351/352 is a serial duplexer that allows two devices to be connected to a single serial port on a UPS. It can be used where numerous serial connections and multiple polling of UPS are required, and is ideal for LAN networks with a firewall. Characteristics • Cascading configuration giving a maximum of 4 serial communication ports • LEDs signalling the communication flow • Firmware upgrade option through the serial port.   for more detail and data sheet go to downloads categories