| 摘要 |
An AC power line communications system includes means for transmitting data to and receiving data from a plurality of transceivers over a conventional AC power distribution network. A central procession unit is provided to poll a plurality of room control units which are placed in each room or designated area of a hotel, hospital or building complex. The central processing unit conducts this polling sequence by periodically transmitting, over the neutral and ground lines of the power distribution network, and interrogation signal having an address portion and a data portion. Each room control unit is arranged to receive the interrogation signal and to compare the address portion of this signal with an address previously programmed into the unit. If the address portion of the interrogation signal corresponds with the programmed address of the room control unit, the unit transmits a return signal to the central processing unit. The room control units uses the data portion of the interrogation signal to report a number of different features of functions within the room (or area) in which the room control unit is located. A sequence of successive, identical addresses is used to allow the room control unit to accept data from the central processor. The central processing unit processes the data contained in the return signal insuring that the data received by the room control unit coincides wih the data transmitted to it by the central processing unit and permitting a record of the data accumulated by the room control unit to be made. This AC power line communications system is well suited to be used in combination with a room status indicating system to monitor the status of each room in buildings such as a hotel, motel, or hospital complex, to monitor the condition of a smoke detector located in each room of the complex, to remotely control the operation of the heating and cooling equipment in each room of the complex, to convey message-waiting information to each room in the complex and to perform an automatic wake-up operation.
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