Bidirectional, interactive fire detection system

• US 4,394,655 A
• Filed: 03/13/1981
• Issued: 07/19/1983
• Est. Priority Date: 03/13/1981
• Status: Expired due to Term

• Current Assignee: ADT Security Services Incorporated (Apollo Global Management, Inc.), Borg-Warner Security Corporation
• Original Assignee: Baker Industries, Inc. (Lincoln Electric Holdings Incorporated)
• Inventors: Wynne, John M., Vogt, William R.
• Primary Examiner(s): YUSKO, DONALD
• Application Number:
  US06/243,401
• Time in Patent Office: 858 Days
• Field of Search: 340/825.54, 340/870.24, 340/870.13, 340/505, 340/509, 340/510, 340/511, 340/514, 340/593, 340/825.36, 340/825.37
• US Class Current: 340/10.41
• CPC Class Codes: G08B 17/00 Fire alarms; Alarms responsive to explosion
• CPC Class Codes: G08B 25/04 using a single signalling line, e.g. in a closed loop

Abstract

The signalling system disclosed herein transmits groups of pulses to a plurality of transponders, and each transponder recognizes its address in a particular group of pulses. The group of pulses can reset the system, command a transponder to accomplish a specific function, or command the transponder to do nothing. Information returned from the transponder includes a reference voltage, which can be compared in the controller to continuously determine the margin from alarm of an associated transducer. The transponder further provides a signal identifying itself, and pulse duration signals representing analog signals received from one or more transducers associated with the transponders. No end-of-line termination is required, and branching is possible at any point along the loop.

Claims

1. A bidirectional, interactive signalling system comprising

a pair of electrical conductors,

a controller coupled to said conductors, for transmitting a series of signal groups sequentially over said conductors, each signal group comprising a plurality of pulse signals, each pulse signal having first and second portions of different amplitude;

and

a plurality of transponders, each coupled to said conductors, each transponder having its own unique address, with each of said transponders being connected to recognize as its address a particular signal group in the series of signal groups transmitted from the controller, and to respond upon recognition of its unique address by transmitting data back to the controller over the same conductor pair, which data may include information regarding a predetermined condition such as alarm and/or trouble, in which said controller transmits one or more commands to a selected one of the transponders by modulating a first portion of at least one signal in the signal group directed to the selected transponder, and the selected transponder replies by modulating the second portion of at least one pulse signal in the same signal group to encode data selected for return to the controller.

2. A signalling system as claimed in claim 1, in which the information returned by the selected transponder is encoded by modulating one or more characteristics of one or more signals within the particular signal group returned to the controller.

3. A bidirectional, interactive signalling system, comprising

a pair of electrical conductors,

a controller coupled to said conductors, for transmitting a series of signal groups sequentially over said conductors, in which each signal group comprises the same number of pulse signals, each pulse signal having a high amplitude portion and a low amplitude portion, and at least one pulse signal has a high amplitude portion modified by extending its time duration to signify command information, and

a plurality of transponders, each coupled to said conductors and each transponder including a counter, circuit means determining its own unique address, and means operative upon recognizing coincidence of its own address with the address represented by the number of signal groups sent by the controller to enable the transponder to respond by transmitting data back to the controller over the same conductor pair, which data may include information regarding a predetermined condition such as alarm and/or trouble, in which said controller transmits one or more commands to the enabled transponder by extending the time duration of the high amplitude portion of at least one signal in the signal group directed to the selected transponder, and the selected transponder replies by extending the low amplitude portion of one of the pulse signals in the same signal group to encode the data selected for return.

4. A signalling system as claimed in claim 3, in which each transponder includes means for receiving an analog signal from an attached device and for transmitting a selected data signal, which is a function of the received analog signal, to the controller when the transponder is enabled and commanded to transmit the data signal.

5. A signalling system as claimed in claim 4, in which the controller includes command means for selectively modifying a high amplitude portion of at least one signal in a signal group in a manner to convey at least one command to the enabled transponder.

6. A signalling system as claimed in claim 4, in which the controller includes means for examining the received data signal to determine whether a predetermined condition is present.

7. A signalling system as claimed in claim 4, in which the controller includes recording means for establishing a record of successive data signals received from the same transponder and thus providing a continuing indication of the sensitivity of the device producing said analog signal.

8. A bidirectional, interactive signalling system for detecting and indicating a predetermined condition, comprising

a pair of line conductors,

a controller coupled to said conductors, for transmitting a series of signal groups sequentially over said conductors, said controller comprising a pair of input conductors across which a voltage V is applied, a first resistor coupled between one of said input conductors and one of said line conductors, means for coupling the other of said input conductors to the other of said line conductors, a second resistor connected between the line conductors at the output side of the controller, a first switch coupled in parallel with the first resistor to short out the first resistor when the switch is closed and pass a voltage V to the line conductors, and circuit means connected to provide a response in accordance with the voltage across the second resistor, and

a plurality of transponders, each coupled to said conductors, each transponder having a series circuit comprising a third resistor and a second switch coupled between the line conductors, all of said resistors having substantially the same resistance value, so that with both switches open a voltage V/2 appears across the second resistor, and with the first switch open and the second switch closed a voltage V/3 appears across the second resistor.

9. A bidirectional, interactive signalling system as claimed in claim 8, in which said controller includes means for regulating opening and closing of the first switch to provide said series of signal groups in which each group has the same number of signal pulses, each pulse having a high amplitude portion and a low amplitude portion, closure of said first switch establishing the high amplitude pulse portion by applying a voltage V across said second resistor, irrespective of the position of the second switch, and opening of said first switch establishing the low amplitude pulse portion across said second resistor at a voltage V/2 when said second switch is open and at a voltage V/3 when said second switch is closed.

10. A bidirectional, interactive signalling system comprising

a pair of electrical conductors,

a controller coupled to said conductors, for transmitting a series of signal groups sequentially over said conductors, in which each signal group comprises the same number of pulses, each pulse having a high amplitude portion and a low amplitude portion, and including command means for selectively extending the time duration of different ones of the high amplitude portions of said pulses in different pulse groups to provide command information, and

a plurality of transponders, each coupled to said conductors and each transponder including a counter, circuit means for determining its own unique address, means operative upon recognizing coincidence of its own address with the address represented by the number of signal groups sent by the controller to enable the transponder to respond to such command information as may be received from the controller, means for receiving an analog signal related to a predetermined condition, and means for transmitting response information, which is a function of the received analog signal, to the controller when the transponder is both enabled and commanded to transmit the response information by selectively extending the time duration of the low amplitude portion of at least one pulse in the same pulse group which contains the command information for the responding transponder.

11. A signalling system as claimed in claim 10, in which the transponder circuit means for determining the address is adjustable to set a desired address in any of the transponders.

12. A signalling system as claimed in claim 10, in which each transponder includes means adjustable to provide an identification signal for transmission to the controller in the same pulse group which contains the command information for the responding transponder, to provide identification of the device forwarding the analog signal to the enabled transponder.

13. A signalling system as claimed in claim 10, in which each transponder includes a signal lamp for selective illumination upon receipt of predetermined command information from the controller.

14. A signalling system as claimed in claim 10, in which at least certain ones of said transponders include an electromechanical actuator connected to be operated in response to receipt of predetermined command information from the controller.

15. A signalling system as claimed in claim 14, in which said electromechanical actuator is a set-reset relay, and the relay is set in response to a first type of command information and is reset in response to a different type of command information.

16. A signalling system as claimed in claim 10, in which a detector for particles of combustion is connected to provide said analog signal to the transponder, and the controller includes an examining circuit for determining, from the response information, whether an alarm condition exists at said detector.

17. A signalling system as claimed in claim 16, in which said examining circuit also determines the sensitivity of the detector from the response information.

18. A signalling system as claimed in claim 16, in which said examining circuit also determines from the response information whether the detector is coupled to its associated transponder.

19. For use in a bidirectional, interactive signalling system in which a series of data groups are sequentially passed over a pair of line conductors, each data group having the same number of pulses and each pulse having a high amplitude portion and a low amplitude portion, each data group carrying command information encoded by modifying a high amplitude portion of one or more pulses in each group, the improvement which comprises

a transponder, coupled to said line conductors and including a counter, circuit means determining its own unique address, means operative upon recognizing coincidence of its own address with the address represented by the number of data groups sent over the line conductors to enable the transponder to provide response information, and means for transmitting the response information over the line conductors in the same data group in which the transponder is both enabled and instructed to transmit the response information by modulating a low amplitude portion of at least one signal in the signal group directed to the enabled transponder.