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Master-slave signal transfer system for elevator

  • US 5,019,960 A
  • Filed: 05/11/1989
  • Issued: 05/28/1991
  • Est. Priority Date: 05/13/1988
  • Status: Expired due to Term
First Claim
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1. A master-slave system for monitoring transmission of elevator cell signals comprising:

  • a plurality of slave stations each having call signal transmission means for transmitting call signals and illuminating call registration lamps;

    a master station which receives said call signals from said slave station and transmits a call registration signal to a slave station responding to a call signal thereupon;

    each of said slave stations having;

    a timer which measures a time interval between transmission of a call signal and receipt of a call registration signal at a respective slave station;

    reply detection means, for transmitting an output signal when a call registration signal has not been received within a predetermined time interval; and

    abnormality detection means operable responsive to the output signal from said reply detection means for initiating retransmission of a call signal and resetting said timer, said abnormality detection means also being operable for extinguishing said call registration lamps when the output signal is not transmitted after retransmitting a call signal a predetermined number of times.

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