There is increasing demand for high-capacity indoor and outdoor units for multi-unit air conditioning systems that have reduced space requirements, improved functionality, and reduced equipment costs. In particular, the requirement will grow for air conditioning systems that consist of one outdoor unit and 100 or more indoor units. The new Super Link II air conditioner communication system plays an important role in supporting the further development of air conditioning systems. While maintaining interchangeability and compatibility with previous communication systems, Super Link II has a new automatic polarity and protocol adjustment algorithm that permits the mixed operation of conventional and new air conditioners with automatic address setting of up to 128 indoor units.