A home automation system comprises a number of sub-systems for controlling various aspects of a house, such as a security sub-system, an HVAC sub-system, a lighting control sub-system, and an entertainment sub-system. The network comprises a host computer connected through a host interface to a plurality of nodes. The network is in a free form topology and employ asynchronous communication. The host computer polls each node on the network to determine system configuration and to perform a diagnostic check on the system. The messages that are transmitted between the nodes are comprised of a source address, a destination address that uniquely identifies the location of each piece of hardware on the system, a message type field, and a data length segment. Each hardware device has a mirror image software object in the host computer to which messages are directed. The user interfaces for the various sub-systems share a common interfacing method whereby use of the system is greatly simplified.