METHOD AND APPARATUS FOR APPLIANCE SERVICE DIAGNOSTICS
BACKGROUND OF THE INVENTION
 The preferred embodiments of the present invention generally relate to service diagnostics, and in particular relate to a method and apparatus for performing service diagnostics on appliances.
 The typical home, office building, or commercial establishment contains several appliances, including refrigerators, microwave ovens, ovens, stoves, heating systems, cooling systems, and the like. Modern appliances are much more sophisticated than their early counterparts, and often include microcontrollers or microprocessors that allow the appliance to be programmed, reprogrammed, and provide diagnostic information, as examples.
 Appliances in homes and other buildings often experience problems that require diagnosis and repair by a service technician. Service technicians must often use complex equipment and methods (that may also be inefficient and inaccurate) to perform service diagnostics on the appliances. Additionally, current manually performed service diagnostics often require the service technician to move and/or dismantle the appliance to locate the problem.
 The Internet has given rise to worldwide connectivity for many types of devices. Appliances, however, only have traditional standalone capability. Three primary communication technologies may be used to provide appliance connectivity: hard wiring, power line carrier (PLC), and wireless.
 Hard wiring (including for example RS-232, RS485, Ethernet, USB, HomePNA, and industrial twisted pair networks) offers superior performance capability (when measured in terms of speed, noise immunity, and the like) at an effective cost. However, a drawback is that additional wiring is required to a home or business. Hard wiring thus poses the significant problem of retrofitting networked appliances into existing homes and businesses and increases cost for new structures.
 PLC uses a 120V or 240V AC power line as a carrier for networking data by modulating the networking data on a high frequency carrier. The high frequency carrier is usually between 100-400 kHz to keep it below the range of FCC regulation. Although older technologies, such as X10, have achieved some market acceptance in lighting applications, they are generally deemed too slow and unreliable for major appliance networking needs. However, newer PLC technologies, such as CEBus and LonWorks, are now commercially available and provide improved data rates and noise immunity at reasonable cost.
 Wireless technologies (such as IEEE 802.11, Bluetooth, HomeRF, and the like) solve the problem of additional wiring by modulating data onto a radio frequency carrier (e.g., at 2.4 GHz) that is broadcast via antenna to desired recipients. Wireless approaches may offer higher bandwidth than PLC technologies currently available, but they do so at a higher cost. Furthermore, since most major appliances are packaged in a sheet steel enclosure (which makes an effective RF shield), antenna placement may be difficult. Cost effective wireless technologies are also subject to distance limitations, potential interference, and poor reception zones
that can often render their use in the home with large, immobile appliances impossible.
 As noted above, the intense manual labor involved in prior appliance diagnosis was unduly wasteful. Nevertheless, it was not previously possible to perform appliance diagnosis using, for example, the any of the physical network media identified above.
 A need has long existed for a method and apparatus for appliance diagnosis that overcomes the problems noted above and other previously experienced.
BRIEF SUMMARY OF THE INVENTION
 A preferred embodiment of the present invention provides a method of performing service diagnostics on appliances. The method comprises connecting to a local area appliance network, accessing an appliance in the local area appliance network, accessing functions of the appliance, and performing service diagnosis of the appliance using the functions. In a preferred embodiment, the local area appliance network is a power line carrier communication carrier network.
 A preferred embodiment of the present invention also provides a diagnostic interface for performing service diagnostics on appliances. The diagnostic interface comprises a display for viewing diagnostic and service information, processing circuitry, and a power line carrier communication interface for transmitting and receiving data on a power line carrier communication system. The diagnostic interface may also include an appliance bus interface and a PC card interface. The diagnostic interface may also connect to a remote system for service diagnostic information.
 An additional preferred embodiment of the present invention provides a system for performing service diagnostics on an appliance. The system comprises a diagnostic interface for performing service diagnostics on the appliance, a local area appliance network, the network allowing access to the appliance, and a dedicated appliance controller. In a preferred embodiment, the local area appliance network comprises a power line carrier network. In a preferred embodiment, the dedicated appliance controller is contained in the appliance. The system may also include a remote system and an Internet connection between the diagnostic interface and the remote system.
BRIEF DESCRIPTION OF THE DRAWINGS
 FIG. 1 illustrates a system for performing service diagnostics on appliances.
 FIG. 2 depicts an implementation of a diagnostic interface for performing service diagnostics on appliances.
 FIG. 3 presents a method for performing service diagnostics on appliances.
 FIG. 4 shows a flow diagram of a method for translating between a power line carrier communication protocol and an appliance communication protocol.
 FIG. 5 shows a software flow diagram for diagnosing and servicing appliances.
 FIG. 6 illustrates a diagnostics system that interfaces through a power line to an appliance.