Synchronized network of electronic devices including back-up master units
First Claim
1. A method of synchronizing a plurality of electronic devices including a master unit and a plurality of other units, comprising the steps of:
- transmitting a synchronizing signal at predetermined intervals from the master unit to at least one of the other units; and
in each of at least two of the other units, detecting whether a synchronizing signal is received by the respective other unit within a respective predetermined period of time and changing a mode of operation of the respective other unit if a synchronizing signal is not received by the respective other unit within the respective predetermined period of time, each of said synchronizing signals for initiating an operation of a device which receives the respective synchronizing signal.
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Accused Products
Abstract
Operation of a plurality of electronic devices is synchronized. The plurality of devices include a master unit and a plurality of other units, and the master unit transmits a synchronizing signal to at least one of the other units at predetermined intervals. Each of at least two of the other units detects whether a synchronizing signal is received at the respective unit within a predetermined period of time. If not, the respective unit changes from a slave mode of operation to a master mode of operation. Contention between the two or more potential back-up master units is resolved based on priority in a daisy-chain arrangement or by providing different time-out watch-dog periods for the potential back-up devices.
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Citations
25 Claims
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1. A method of synchronizing a plurality of electronic devices including a master unit and a plurality of other units, comprising the steps of:
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transmitting a synchronizing signal at predetermined intervals from the master unit to at least one of the other units; and in each of at least two of the other units, detecting whether a synchronizing signal is received by the respective other unit within a respective predetermined period of time and changing a mode of operation of the respective other unit if a synchronizing signal is not received by the respective other unit within the respective predetermined period of time, each of said synchronizing signals for initiating an operation of a device which receives the respective synchronizing signal. - View Dependent Claims (2, 3)
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4. A synchronized network of electronic devices, comprising a plurality of electronic devices and means for interconnecting the devices for transmission of synchronizing signals among the devices, each said synchronizing signals for initiating an operation of a device which receives the respective synchronizing signal, said plurality of electronic devices including:
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(a) a master unit for transmitting a synchronizing signal at predetermined intervals to at least one other of said electronic devices, and (b) at least two back-up units each for detecting whether a synchronizing signal is received by the respective back-up unit within a respective predetermined period of time and for transmitting a synchronizing signal at predetermined intervals if a synchronizing signal is not received by the respective back-up unit within the respective predetermined period of time. - View Dependent Claims (5, 6, 7, 8, 9, 10)
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11. A synchronized network of electronic devices, comprising:
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a master device including means for generating synchronizing signals at regular intervals and an output terminal for outputting the synchronizing signals; a second device including an input terminal connected to the output terminal of the master device, means for generating a synchronizing signal in response to receipt of a synchronizing signal at the input terminal, and an output terminal for outputting the synchronizing signal generated by the means for generating of the second device; and a third device including an input terminal connected to the output terminal of the second device, means for generating a synchronizing signal in response to receipt of a synchronizing signal at the input terminal of the third device, and an output terminal for outputting the synchronizing signal generated by the means for generating of the third device; said second device further including means for determining whether a synchronizing signal is received at the input terminal of the second device during a predetermined period of time and for generating synchronizing signals at regular intervals if it is determined that no synchronizing signal is received at the input terminal of the second device during the predetermined period of time, each of said synchronizing signals for initiating an operation of a device which receives the respective synchronizing signal. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A device for reading an electronic article surveillance marker, comprising:
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receive means for receiving a synchronizing signal; means for generating, in response to receipt of the synchronizing signal by the receive means, an interrogation signal for interrogating the marker; control means for determining whether a synchronizing signal is received by the receive means during a predetermined period of time; and sync means, responsive to the control means, for generating periodic synchronizing signals at regular intervals, and for generating interrogation signals at regular intervals in synchronism with the periodic synchronizing signals generated at regular intervals, if it is determined by the control means that no synchronizing signal is received by the receive means during the predetermined period of time, each of said synchronizing signals for initiating an operation of a device which receives the respective synchronizing signal. - View Dependent Claims (20, 21)
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22. A device for reading an electronic article surveillance marker, comprising:
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receive means for receiving synchronization signals; interrogation means for generating interrogation signals for interrogating the marker; and sync means for generating synchronization signals; the device being selectively operated in a first mode of operation in which the interrogation means and the sync means are each responsive to the receive means for respectively generating an interrogation signal and a synchronization signal upon receipt of the synchronization signal by the receive means and a second mode of operation in which the interrogation means and the sync means respectively generate interrogation signals and synchronization signals at regular intervals in synchronism with each other during periods in which the receive means receives no synchronization signals, the device further comprising control means, operatively associated with the receive means, the interrogation means and the sync means, for switching the device between the first and second modes of operation, each of said synchronization signals for initiating an operation of a device which receives the respective synchronization signal. - View Dependent Claims (23, 24, 25)
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Specification