| 摘要 |
PROBLEM TO BE SOLVED: To provide a unit that can necessarily attain connection and communi cation, with at least one unit and receive an audio-visual program. SOLUTION: The unit 1 of this invention is provided with a circuit for communication with a connection means to a two-way communication network to receive the audio visual program. A 1st connector 11 is used for communication with a master unit 2. A 2nd connector 12 is used for communication with peripheral units 4, 5. A transmission means transmits a supply voltage on the 1st connector 11 generated from the master unit 2. A detection means 100 detects the presence of a supply voltage VBUS on the 1st connector 11. The detention means 100 controls a switching circuit 13, so as to operate the unit 1 in master mode with respect to the peripheral units 4, 5, when no supply voltage exists and so as to operate the unit 1 in a slave mode, with respect to the master unit 2 when the supply voltage exists.
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