MicroTTU is a flexible, multi-port, and precisely timed subsea serial multiplexor designed to withstand the harsh environment of ROV operations. MicroTTU uses a single ROV serial channel to add six channels or ports for additional communication capability to any ROV, AUV, or Towfish. All sensor data is appended with a precise time tag or exported to either a virtual or real serial port in the same form as the original sensor data. Also, a data logging option is supplied within the surface software for individual channel logging to separate files.