The UIMM is simply an Inductive Modem Module (IMM) housed in a pressure case and incorporating an integral inductive coupler and cable clamp. It is designed to be cable-connected to an RS-232 serial instrument, and then clamped to the jacketed mooring wire.
The UIMM can also be used as a substitute for an IMM (housed inside a buoy) and an Inductive Cable Coupler (ICC); it receives inductive communications from other underwater IM devices and sends the data via RS-232 to the surface buoy (or bottom junction in a cabled observatory). The IMM is user-configured via RS-232 to send and receive commands to control the serial instrument and receive or retrieve data. Through its 4-pin connector, the UIMM communicates with the RS-232 instrument and consumes a small amount of power from it.