Monopolar, synchronized communication system

• US 6,577,232 B1
• Filed: 10/31/2000
• Issued: 06/10/2003
• Est. Priority Date: 11/02/1998
• Status: Expired due to Term

• Current Assignee: Pittway Corporation (Honeywell International Inc.)
• Original Assignee: Pittway Corporation (Honeywell International Inc.)
• Inventors: Hawkinson, Daniel C., Bohannon, Mark C., Doll, David C., Clow, Robert J.
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US09/702,502
• Time in Patent Office: 952 Days
• Field of Search: 340/505, 340/506, 340/512, 340/513, 340/514, 340/3.1, 340/3.2
• US Class Current: 340/505
• CPC Class Codes: G08B 26/004 with common interrogation of substations
• CPC Class Codes: H04L 25/029 Provision of high-impedance states
• CPC Class Codes: H04L 25/49 using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems spectral shaping H04L25/03828

Abstract

A communication protocol facilitates transmission at maximum rates for various types of cables. The protocol can be used to transmit information between a common control unit and a plurality of spaced apart devices coupled thereto. Alternately, the protocol can be used for transmission of information between devices. One control unit or device transmits clock pulses, while in a low impedance state. The devices respond to the clock pulses and transmit data on the communications link, in a low impedance state, when the source of clock pulses assumes a high impedance state. One or more features of transmitted signals can be used to implement one or more synchronized functions.

Claims

1. A communication apparatus comprising:

a source;

a multi-conductor communications medium, coupled to the source, wherein the source includes drive circuitry for impressing on at least one of the conductors of the medium a plurality of spaced apart, synchronization signals and a plurality of voltage-type clock pulses of a first polarity therebetween;

at least one electrical device, coupled to the medium, wherein the device includes receiver circuitry for detecting the synchronizing signals and for generating in the device electrical signals responsive thereto, wherein the device further includes transmitter circuitry for producing a plurality of spaced apart, data pulses on the at least one conductor wherein the data pulses are produced by the device as voltage pulses with the same polarity and wherein at least some of the clock pulses are between data pulses.

2. An apparatus as in claim 1 wherein the source includes circuitry for generating voltage clock pulses with a relatively low output impedance and for switching to a relatively high output impedance between clock pulses.

3. An apparatus as in claim 2 wherein the drive circuitry includes circuitry for generating as synchronization signals first and second spaced apart bounding waveforms with the clock pulses positioned therebetween.

4. An apparatus as in claim 1 wherein the synchronizing signals comprise selected transitions of voltage pulses.

5. An apparatus as in claim 1 wherein the synchronizing signals comprise selected current values.

6. An apparatus as in claim 1 wherein the medium provides electrical energy, to be stored in the device, between synchronization signals.

7. An apparatus as in claim 6 wherein the electrical unit includes energy storage circuitry for receiving and storing electrical energy from the medium between synchronization signals.

8. An apparatus as in claim 7 wherein the unit includes circuitry, powered by the energy storage circuitry for coupling the data pulses to the medium.

9. An apparatus as in claim 8 wherein the synchronization signals induced by the source drive circuitry comprise voltage transitions having substantially the same amplitudes.

10. An apparatus as in claim 1 wherein the device includes circuitry for transmitting data pulses to another device.

11. An apparatus as in claim 10 which includes a second electrical device, coupled to the medium, wherein the second device includes circuitry, responsive to the synchronizing signals and to the data pulses from the first device to carry out a predetermined, synchronized, function.

12. An apparatus as in claim 11 wherein one device comprises a condition detector and another device comprises an output function module.

13. An apparatus as in claim 12 wherein the source comprises a source of frame defining voltage pulses.

14. An apparatus as in claim 12 wherein the condition detector comprises one of a fire detector and a gas detector and the output function module comprises one of a visual alarm indicating output device and an audible alarm indicating output device.

15. A system as in claim 1 wherein the electrical device comprises an ambient condition detector which includes circuitry for detecting an ambient condition and for transmitting alarm indicating data pulses indicative thereof on the medium;

and

a plurality of output devices, coupled to the medium, for emitting at least one of an audible alarm signal and a visible alarm signal in response to the alarm indicating data pulses wherein the output devices emit in synchronism in response to the synchronization signals.

16. A communication apparatus comprising

a voltage drive source;

at least a two-wire medium for communication, coupled to the source, wherein the source includes drive circuitry for impressing on the medium a plurality of spaced apart, voltage-type clock pulses of a first polarity across two of the wires and a plurality of synchronizing signals;

an electrical device, coupled to the medium, wherein the device includes circuitry for detecting the voltage-type clock pulses and the synchronizing signals and for generating in the device electrical signals responsive thereto;

wherein the device contains a storage circuit for storing energy received between synchronizing signals; and

wherein the device further includes transmitter circuitry for driving the medium, from the energy source in the device, with a plurality of spaced apart voltage-type data pulses, having the same polarity, across the two wires.

17. An apparatus as in claim 16 wherein the source includes circuitry for generating at least one of voltage-type synchronizing signals, and synchronizing current signals.

18. An apparatus as in claim 16 wherein the device includes circuitry which establishes at least one threshold detection level and includes circuitry coupled thereto to detect the synchronizing signals.

19. An apparatus as in claim 16 which includes a second device, wherein the devices include circuitry for transmitting messages therebetween.

20. An apparatus as in claim 19 wherein one device comprises a detector having a sensor and another device includes a module having an output transducer wherein the transducer is energized in time in accordance with the synchronizing signals.

21. In a communication system, a method of communicating comprising:

providing a start-frame indicator by altering a line voltage of a first polarity relative to a predetermined value;

generating clock pulse voltages with the first polarity;

switching between high and low impedance time intervals;

sending data pulses of the same polarity during a high impedance time interval;

providing an end-frame indicator for the message by returning the line voltage to the predetermined value.

22. A method as in claim 21 which includes:

detecting the start frame indicator at one device and in response thereto generating a message, in the form of data pulses, to a different device.

23. A method as in claim 22 where the devices exhibit a high impedance unless transmitting a data pulse.

24. A communications system comprising:

circuitry for sequentially producing a plurality of communications cycles wherein each cycle includes a data phase and a power phase with each data phase including a data phase start signal and a plurality of spaced apart voltage clock pulses wherein the clock pulses are output with a first polarity while the circuitry exhibits a first output impedance and with each power phase exhibiting an output voltage of the first polarity while the circuitry exhibits the first output impedance and wherein the circuitry exhibits a second, higher, output impedance between clock pulses;

a wired communications medium, coupled to the circuitry, and extending therefrom;

a plurality of electrical units, coupled to the medium, wherein the units each include energy storage circuitry for receiving energy from the medium during the power phase wherein the energy storage circuitry is decoupled from the medium during the data phase.

25. A system as in claim 24 wherein the units each include interface circuitry coupled to the medium and having third and fourth output impedances with the third being substantially greater than the fourth, control circuitry coupled to the interface circuitry for coupling pluralities of binary data sequences, via the interface circuitry, to the medium between clock pulses wherein at least some of the data sequences include spaced apart bit positions with some of the bit positions being coupled to the medium with the fourth output impedance and wherein data in some of the bit positions are represented by voltage pulses having the first polarity.

26. A system as in claim 24 wherein each power phase ends with a start of cycle transition and each data phase ends with an end of cycle transition.

27. A system as in claim 26 wherein one transition is opposite the other.

28. A system as in claim 26 wherein the cycle producing circuitry does not impart electrical energy to the medium between clock pulses.

29. A system as in claim 28 wherein the units do not impart electrical energy to the medium, between clock pulses unless a selected binary value is to be coupled thereto.

30. A system as in claim 29 wherein the units do not impart electrical energy to the medium between clock pulses where another binary value is to be coupled thereto.

31. A system as in claim 26 wherein the pluralities of binary data sequences correspond to data bytes and the cycle transitions bound transmissions via the medium having variable numbers of bytes.

32. A system as in claim 26 wherein the cycle producing circuitry generates an end clock before the end of cycle transition.

33. A system as in claim 29 wherein the cycle producing circuitry generates a transmission rate indicium after the start of cycle transition.

34. A system as in claim 26 which includes a time interval before the end of cycle transition wherein a unit can transmit a transmission quality indicator, via the medium, to other units.

35. A system as in claim 26 wherein at least some of the units include at least one ambient condition sensor.

36. A system as in claim 35 wherein the sensors are selected from a class which includes a smoke sensor, a gas sensor, a heat sensor, a movement sensor, and a position sensor.

37. A system as in claim 26 wherein the units include a processor and executable instructions for transmitting messages to other units via the medium during the data phase.

38. A system as in claim 37 which includes a system control device coupled to the medium.

39. A system as in claim 37 wherein some of the units include circuitry for carrying out an output function.

40. A system as in claim 39 wherein the output function is selected from a class which includes energizing a solenoid, energizing a visual output device, energizing an audible output device, and de-energizing an air moving device.