Smart Adapter for Digital Appliances
February 2004
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A technology from Wrap S.p.A called Power Modulation combines digital appliances and a new device called the Smart Adapter. The device is used for connecting electrical appliances through networking. It has a communication node and a power meter, and is located between an electrical appliance and its outlet. Through the communication node, the adapter can communicate with the home bus; through the power meter, it can analyze the electric current absorbed by the appliance and generate useful functional and diagnostic data related to the appliance.

When used with a digital appliance, the adapter can directly communicate by using its internal power meter to measure the electric current absorbed by the appliance during each cycle of the mains. Using this concept, the digital appliance is reportedly able to send at least a bit per cycle (i.e., 50 or 60 bits per sec, depending on the value of the powerline frequency). It absorbs a small electric current (10 mA) from the mains using a small triac, driving a suitable and inexpensive resistive load, the company says.

Furthermore, the adapter can send commands to the digital appliance by creating short and precise interruptions on the power supply applied to the appliance itself; the digital control system of the appliance can then easily decode such commands measuring the variation of the period between two consecutive zero-crossing transitions of the power line voltage. The adapter is reportedly able to send at least one nibble (4 bits) at a time, without affecting the functionality of the appliance.

The communications between the appliance and the Smart Adapter is managed by a specific hardware peripheral (Macrocell) embedded in a next-generation microcontroller specifically designed for the appliance industry.

According to the company, using the smart adapter, power modulation is a simple method to reliably transfer information from the appliance to the wiring system, without adding any significant costs to the appliance itself. The company also says the technology is capable of generating value in the short term - becoming an efficient and useful tool for white goods appliance in-line testing and accurately checking all of the electric components within the appliance.

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