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Lead line supervision system

  • US 5,181,241 A
  • Filed: 04/30/1991
  • Issued: 01/19/1993
  • Est. Priority Date: 06/20/1986
  • Status: Expired due to Term
First Claim
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1. A method for detecting malfunction conditions in a data transmission system including a data transmitting station and a remote data receiving station connected via a data transmission media having first and second data transmission lines, said data transmitting station including output switching means having a first terminal coupled with said first data transmission line and a second output terminal coupled with said second data transmission line operable with said data receiving to provide data pulses thereto, and output current gating means coupled between said first and second data transmission lines, said method comprising:

  • aplying a potential of a first polarity to said data transmitting station;

    generating data pulses of said first polarity upon periodic closures of said switching means;

    detecting the presence of each of said data pulses of said first polarity continuing for a first preselected duration; and

    providing a first output signal when the presence of said data pulses of said first polarity exceeds said first preselected duration.

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