Bidirectional communication between control element and electrical devices

• US 6,424,257 B1
• Filed: 04/18/2000
• Issued: 07/23/2002
• Est. Priority Date: 04/18/2000
• Status: Expired due to Term

• Current Assignee: Pittway Corporation (Honeywell International Inc.)
• Original Assignee: Pittway Corporation (Honeywell International Inc.)
• Inventors: Rauworth, Timothy A., Jen, Hsing C., Slater, James S.
• Primary Examiner(s): POPE, DARYL C
• Application Number:
  US09/551,379
• Time in Patent Office: 826 Days
• Field of Search: 340/511, 340/501, 340/518, 340/3.1
• US Class Current: 340/506
• CPC Class Codes: G08B 17/10 Actuation by presence of smoke or gases , e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
• CPC Class Codes: G08B 26/002 only replying the state of the sensor

Abstract

A software driven monitoring system includes a common control element coupled to a plurality of monitoring devices. The devices can indicate to the control element that a predetermined condition has been detected. Where the control element transmits a status inquiry command to the devices, those devices exhibiting the status provide the same indication to the control element as is indicative of the predetermined condition. One indication is a shunt or a short circuit of a medium between the common control element and the devices. An existing system can be upgraded by installing the control element, or upgrading an existing control program. Alternately, the devices can be installed in a system wherein the control element does not issue the status inquiry command. In those installations, the monitoring devices never issue a status reply as the required command is never received.

Claims

1. A dual mode fire detector usable in first and second different types of alarm systems, the first type of system having a control unit coupled by a cable to a plurality of detectors wherein the detectors, on detecting a fire condition, exhibit a latched alarm indicating condition on the cable, producing a predetermined current flow on the cable, wherein the current flow is detectable by the control unit as an indication of an alarm condition and wherein the control unit interrupts the alarm indicating current flow thereby resetting all of the detectors substantially simultaneously, and, wherein the second type of system has a different control element coupled to a second cable and alarm indicating fire detectors are coupled to the second cable, wherein the fire detectors each produce a current flow in the second cable in response to a fire and wherein the different control element includes circuitry for sending at least one status requesting message to the detectors via the second cable wherein the detectors exhibiting the requested status respond to the different control element'"'"'s status requesting message by each producing the same current flow on the second cable as the respective detector would produce thereon to indicate a fire, the dual mode detector comprising:

a fire sensor;

control circuits, coupled to the sensor and couplable to a communication cable, wherein the control circuits receive fire indicating signals from the sensor and status requesting signals from the cable, wherein the control circuits produce a current flow on the cable to indicate a fire condition and the same current flow is produced on the cable, in response to a received status request, to indicate the existence of the requested status, and where in the absence of status requesting signals, only a fire, sensed by the fire sensor produces the current flow.

2. A detector as in claim 1 wherein the current flow is produced by the control circuits exhibiting a change from a first impedance to a second impedance.

3. A detector as in claim 1 wherein the current flow produced in response to a status requesting signal is produced until electrical energy flowing to the control circuits is interrupted.

4. A device for communicating status in an alarm or security system which includes:

first circuitry to generate at least one output signal, and second circuitry for receiving at least one status request signal, and wherein the first circuitry will generate the output signal in response to receipt of the status request signal if the device is exhibiting a non-alarm status which corresponds to the received status request and wherein at least the first circuitry will generate the output signal independently of the status request signal if the device is exhibiting an alarm condition.

5. A device as in claim 4 wherein the output signal is generated by a change in an impedance value of the first circuitry from a first impedance value to a lower, latched impedance value.

6. A device as in claim 5 wherein the change in impedance value produces a current flow.

7. A device as in claim 4 wherein the device exhibiting the respective status will send the status indicating output signal during at least a predetermined time period following the received status request signal.

8. A device as in claim 4 which includes terminals for coupling to a wired communications medium;

and wherein the output signal generated by the first circuitry is a latched signal which is reset by interrupting electrical energy received from the wired medium.

9. A device as in claim 4 which includes at least one sensor selected from a class which includes at least a smoke sensor, a thermal sensor, a flame sensor, a gas sensor, an intrusion sensor, a position sensor, a motion sensor, and a flow sensor.

10. An ambient condition detector usable in two different types of monitoring systems wherein one system includes functions not present in the other, the detector comprising:

an ambient condition sensor; and

control circuits, coupled to the sensor and couplable to a wired medium, wherein the control circuits receive condition indicating signals from the sensor, and, status requesting signals from the medium, wherein the control circuits go from a first output state to a second output state in response to the existence of a predetermined ambient alarm condition, and the same change from the first to the second output state is exhibited in response to a received status request, to indicate the existence of the requested status, and, where in the absence of status requesting signals, only the sensed, predetermined ambient alarm condition produces the same change in output state.

11. A detector as in claim 10 wherein the control circuits include further circuitry whereby the second output state is a latched state whereupon the latched second output state can only be reset to the first output state by interrupting a flow of electrical energy to at least the control circuits.

12. A monitoring system comprising a communications medium;

a plurality of detectors coupled to the medium wherein each detector comprises an ambient condition sensor; and

control circuits, coupled to the sensor and couplable to a wired medium, wherein the control circuits receive condition indicating signals from the sensor and status requesting signals from the medium, wherein the control circuits go from a first output state to a second latching output state in response to the existence of a predetermined ambient alarm condition, and the same change of output state is exhibited in response to a received status request, to indicate the existence of the requested status, and, where in the absence of status requesting signals, only the sensed, predetermined ambient alarm condition produces the change in output state; and

wherein the communications medium is serially couplable to each of first and second common control units without modifying any of the detectors, wherein the first control unit detects current flowing in the medium in response only to at least one detector exhibiting an alarm condition and wherein the first control unit communicates with the detectors by resetting all detectors in the system, thereby interrupting the current flow and wherein the second control unit detects current flowing in the medium in response to at least one detector exhibiting an alarm condition, and also at a different time, detects the same current flowing in the medium, after sending a status request to the members of the plurality provided that the at least one detector is exhibiting the requested status.

13. A system as in claim 12 wherein the change in output states corresponds to a change in an impedance value of the control circuit from a first impedance value to a lower impedance value.

14. A system as in claim 13 wherein the change in impedance value produces a current flow.

15. A system as in claim 14 which includes a system control unit for resetting the detectors from the latched second state to the first state.

16. A system as in claim 12 which includes at least one sensor selected from a class which includes at least a smoke sensor, a thermal sensor, a flame sensor, a gas sensor, an intrusion sensor, a position sensor, a motion sensor, and a flow sensor.

17. A device for communicating status in an alarm or security system which includes:

first circuitry to generate at least one output signal, and second circuitry for receiving at least one status request signal, and wherein the first circuitry will generate the output signal in response to receipt of the status request signal and wherein at least the first circuitry will generate the output signal independently of the status request signal if the device is exhibiting an alarm condition;

thus allowing the device to operate in at least two different types of systems.

18. A device as in claim 17 wherein the at least two different types of systems include a first system that generates status request signals and a second system that does not generate status request signals.

19. A device as in claim 18 wherein the device only provides alarm signals in the second system and the second system does not generate status request signals.

20. A device as in claim 18 wherein the device provides alarm signals and non-alarm status request signals in the first system and the first system generates status request signals.

21. A device as in claim 17 wherein the at least two different types of systems include a first system that generates status request signals and has additional circuitry for use in a second system that does not generate status request signals.

22. A device as in claim 17 wherein the output signal is generated by a change in impedance value of the first circuitry from a first impedance value to a lower impedance value.

23. A device as in claim 17 wherein the device exhibiting a respective status will send the respective status indicating the output signal during a predetermined time period following the received status request signal.

24. A device as in claim 17 which further comprises at least one smoke sensor.

25. A device as in claim 24 which further comprises at least one of a thermal sensor, a flame sensor, a gas sensor, an intrusion sensor, a position sensor, a motion sensor, and a flow sensor.