ARINC Specification 485, Part 2 specifies the ARINC 485-control protocol used by the LRUs described in ARINC Specification 628 Part 2. This document defines a multi-drop bus. The point-to-point configuration is also supported. The point-to-point bus is treated simply as a multi-drop bus with only one drop. There is one master LRU and one or more slave LRUs present on the bus. However; multiple buses may be connected in parallel, where each parallel bus operates independently from each other.