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Building technical management controller with a two-wire data and power transmission line

  • US 5,089,974 A
  • Filed: 11/02/1989
  • Issued: 02/18/1992
  • Est. Priority Date: 11/04/1988
  • Status: Expired due to Term
First Claim
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1. An integrated power and data transmission apparatus for controlling the operation of electrical equipment in a building comprising:

  • a two-wire bus including a first line acting as a voltage supply line and a second line acting as a return line for power and asynchronous data transmission;

    a power supply means for providing a low level DC voltage to said two-wire bus, said power supply means including a current limiter for limiting the current supplied by said power supply means to said two-wire bus when said supply line and said return line are short-circuited;

    a plurality of independently addressable modules coupled to said two-wire bus and powered by said power supply means, said plurality of modules including at least one module which transmits a command signal and one module which performs a preprogrammed function in response to said command signal, wherein each of said plurality of modules includes;

    a) data transmission and data reception means for performing data transmission and data reception with another module;

    b) a programmable microcontroller for controlling the operation of the module including performance of said preprogrammed function and said data transmission and data reception;

    c) interface means coupled to said two-wire bus including means for providing uninterrupted power to the module and short-circuiting means controlled by said programmable microcontroller for short-circuiting said supply line to said return line; and

    d) data communication priority means for determining a priority of data communication for the module including mans for detecting when a difference occurs between a signal present on said two-wire bus with a data transmission signal output from the module and withdrawing from data transmission when said difference is detected;

    wherein data is transmitted on said two-wire bus as a binary DC signal with a logic high represented by the presence of a supply voltage of the two-wire bus and a logic low represented by a zero voltage on the two-wire bus caused by the short-circuiting of said supply line with said return line.

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