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Heartbeat communications

  • US 5,631,629 A
  • Filed: 02/08/1995
  • Issued: 05/20/1997
  • Est. Priority Date: 02/08/1995
  • Status: Expired due to Term
First Claim
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1. A dual channel communications method comprising:

  • (A) providing a control system with a central control station and a remote sensor for sensing a process status, said central control station and said remote sensor being connected by a power supply line and an output line;

    (B) impressing a non-periodic high-amplitude process status signal on said output line at said remote sensor so as to transfer status information about said process status to said central control station;

    (C) simultaneously impressing a periodic low-amplitude low-frequency diagnostic condition signal on said output line at said remote sensor so as to transfer diagnostic information about an operating condition of said remote sensor to said central control station;

    (D) monitoring the electrical state of said output line at said central control station to detect the level of said non-periodic high-amplitude process status signal so as to receive status information about said process status at said central control station; and

    (E) monitoring the electrical state of said output line at said central control station to detect the presence of said periodic low-amplitude low-frequency diagnostic condition signal so as to receive diagnostic information about i) said operating condition of said remote sensor, ii) said power supply line and iii) said output line at said central control station.

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