The 1U643-001 Breakout Box and Data Logger is a diagnostics tool for monitoring aircraft systems by providing a test point breakout between various electronic modules and their associated interconnects with the aircraft. The 1U643-001 was designed as a dual-purpose tool. It can be used stand alone as a normal breakout box or, when connected to a notebook computer via the RS232 serial port, as a data viewing, logging, and recording instrument. The 1U643-001 data logger allows diagnosis of aircraft system malfunctions by enabling the user to record data from aircraft systems for later viewing by knowledgeable systems engineers or technicians.