Time division multiple access communication system for status monitoring

• US 3,927,404 A
• Filed: 10/18/1973
• Issued: 12/16/1975
• Est. Priority Date: 10/18/1973
• Status: Expired due to Term

• Current Assignee: Glenn F. Cooper
• Original Assignee: Glenn F. Cooper
• Inventors: Cooper, Glenn F.
• Primary Examiner(s): Habecker, Thomas B.
• Application Number:
  US05/407,660
• Time in Patent Office: 789 Days
• Field of Search: 340/413,152R,150,408
• US Class Current: 340/518
• CPC Class Codes: G08B 26/002 only replying the state of the sensor

Abstract

A communication system wherein data at a plurality of different zones is transmitted to a control panel at a central location over a common communication line including an address pulse generator at the central location which transmits a programmed number of address pulses over the communication line to effect sequential enabling of zone status monitors at each of the zones, each of which obtains power from the address pulses, and provides frequency signals representing a normal or off-normal condition for a variable for transmission over the communication line to the central location, and a receiver at the central location which decodes and processes the responses. A number of zone status monitors may be divided into groups with each group transmitting data to a central location over an area address pulse generator which is connected to the communication line, or multiple communication lines may be monitored from a master control panel through the use of slave control panels.

Claims

1. In a communication system for reporting information from a plurality of remote locations to a control location over a common communication channel, monitoring means at each of said remote locations including signal generating means operable to provide an information signal representing the condition of at least one variable monitored by said monitoring means for transmission over said communication channel to said control location, the signal generating means of different monitoring means being operable to provide an information signal during a different preassigned time slot, and master control means at said control location, including means for generating a synchronizing signal for defining the time slots for said monitoring means, and at least one slave control means connected in a local loop with at least certain ones of said monitoring means, said slave control means being connected to said common communication channel to receive said synchronizing signal and to responsively provide a further synchronizing signal for transmission over said local loop for controlling the operation of said certain monitoring means.

2. A system as set forth in claim 1 wherein said master control means further includes receiver means for receiving the responses provided by all of said monitoring means.

3. A system as set forth in claim 2 wherein said slave control means includes receiver means for receiving the responses provided by all said monitoring means.

4. A system as set fortH in claim 1 wherein said slave control means is normally controlled by the synchronizing signal provided by said master control means, said slave control means being operable to independently generate said further synchronizing signal in the event of interruption of the transmission of said synchronizing signal over said common communication channel.

5. In a communication system for reporting information from a plurality of remote locations to a control location over a common communication channel, a plurality of monitoring means each connected to said transmission line at a different one of said locations, means at one of said locations including address means having pulse generating means for generating a series of address pulses defining a time frame for transmission over said communication channel to said remote locations, the end of each of said address pulses defining the start of a time slot and the number of address pulses defining the number of time slots, and enabling means for controlling said pulse generating means to select the number of pulses in each time frame to provide a separate address pulse for each of said monitoring means to thereby define an individual response time slot for each monitoring means, each of said monitoring means, including response generating means and including pulse counting means for counting said address pulses and responsive to a predetermined number of said address pulses to enable the corresponding response generating means to provide a response signal representing the condition of at least one variable monitored by said monitoring means, the pulse counting means of different monitoring means being responsive to a different preselected number of said pulses of the series of address pulses to enable the corresponding response generating means to provide a response signal during a different preselected time slot for transmission over said communication channel to said one location.

6. In a communication system for reporting information from a plurality of remote locations to a control location over a common transmission line, a plurality of monitoring means each connected to said transmission line at a different one of said locations, control means connected to said transmission line at said control location and including address pulses generator means having pulse generating means for generating a series of address pulses defining a time frame for transmission over said transmission line to each of said monitoring means at said remote locations, the end of each address pulse defining the start of a time slot and the number of address pulses defining the number of time slots, and enabling means for controlling said pulse generating means to select the number of pulses in each time frame to provide a separate address pulse for each of said monitoring means to thereby define an individual response time slot for each monitoring means, each of said monitoring means including response generating means operable when enabled to provide a response signal for transmission over said transmission line to said control location, and pulse counting means for counting said address pulses and for effecting the enabling of an associated response generating means when a preassigned number of address pulses have been counted, the pulse counting means of different monitoring means being responsive to a different number of pulses of the series of address pulses transmitted over said transmission line to provide an enabling signal for an associated response generating means whereby the response signals provided by different ones of the response generating means are transmitted to the control location during different preselected time slots.

7. A system as set forth in claim 6 wherein said pulse generating means includes time slot rate generating means for continuously generating clock pulses at a predetermined rate, power amplifier means, gating means operable when enabled to extend clock pulses to said power amplifier means to enable sAid power amplifier means to provide power address pulses, said enabling means being responsive to said clock pulses for enabling said gating means to pass a preselected number of said clock pulses to said power amplifier means to define the number of address pulses and therefore the number of time slots that are provided.

8. A system as set forth in claim 7 wherein said power amplifier means comprises operational transconductance amplifier means having an input connected to the output of said gating means to receive said clock pulses and capacitor means connected to an output of said operational amplifier means, said operational amplifier means being responsive to each clock pulse extended thereto to provide output current for causing said capacitor means to charge at a linear rate and to discharge at a non-linear rate to thereby provide current pulses having different rise and fall times.

9. A system as set forth in claim 6 wherein said address pulse generator means transmits a number of address pulses sufficient to define a separate time slot for each monitoring means and a further time slot.

10. A system as set forth in claim 9 wherein said control means includes transmission line continuity test means including means enabled during said further time slot to test the continuity of said transmission line during said further time slot.

11. A system as set forth in claim 9 wherein each of said monitoring means are normally unpowered, each said monitoring means including power circuit means responsive to a first one of the address pulses to provide an energizing signal for the corresponding pulse counting means to enable said pulse counting means to count further address pulses, and gating means, enabled by said pulse counting means after a preselected number of address pulses have been counted, to extend said energizing signal to the corresponding response generating means to enable the response generating means to provide a response signal during a preassigned one of the time slots.

12. In a communication system for reporting information from a plurality of remote locations to a control location, a plurality of monitoring means including a separate monitoring means at each of said remote locations operable to provide an information signal representing the condition of at least one variable monitored by said monitoring means for transmission to said control location, control means at said control location for providing a synchronizing signal for transmission to said remote locations for synchronizing the operation of all of said monitoring means, and transmission line means connecting said monitoring means and said control means in a continuous loop enabling bidirectional transmission between said control means and said monitoring means over first and second paths.

13. In a communication system for reporting information including normal and off-normal conditions for a plurality of variables from a plurality of remote locations to a control location over a common transmission line, a plurality of monitoring means, each connected to said transmission line at a different one of said locations, control means connected to said transmission line at said control location including time slot rate generating means for continuously generating clock pulses at a predetermined rate, power amplifier means, gating means operable when enabled to extend clock pulses to said power amplifier means to enable said power amplifier means to provide power address pulses and enabling means responsive to said clock pulses for enabling said gating means to pass a preselected number of said clock pulses to said power amplifier means to provide a separate address pulse for each of said monitoring means, the end of each address pulse defining the start of a response time slot for one of said monitoring means and the number of said address pulses defining the number of time slots, each of said monitoring means including initiating means having a plurality of condition sensing means each of whiCh indicates a normal or off-normal condition for a different one of a plurality of variables, response generating means including means operable when enabled to normally provide a response signal at a first frequency indicative of a normal condition for all of said variables, said response signal generating means being selectively controllable by said initiating means in the event of an off-normal condition for one or more of said variables to generate a response signal at a different frequency, means for coupling the response signal to said transmission line for transmission to said control location, and pulse counting means for counting said address pulses and for effecting the enabling of an associated response generating means when a predetermined number of said address pulses have been counted, the pulse counting means of different monitoring means being responsive to a different number of address pulses to provide an enabling signal for an associated response generating means whereby the response signals provided by different ones of said response generating means are transmitted to said control location during a different preassigned time slot.

14. In a communication system for reporting information from a plurality of remote locations to a control location, including a communication channel for carrying periodically receiving synchronizing pulses, the end of each synchronizing pulse defining a time slot and the number of synchronizing pulses defining the number of time slots, detecting means for detecting said synchronizing pulses and for providing a control output for each synchronizing pulse detected, comprising first monostable circuit means enabled by each synchronizing pulse to provide an output signal for approximately the duration of the synchronizing pulse and the time slot defined by the synchronizing pulse, and second monostable circuit means enabled by the output signal provided by said first monostable circuit means to provide said control signal.

15. In a communication system for reporting information from a plurality of remote locations to a control location over a common transmission loop, monitoring means at each of said remote locations operable to provide an information signal representing the condition of at least one variable monitored by said monitoring means, control means at said control location including synchronizing means including means for generating a plurality of synchronizing pulses for transmission over said common loop for controlling the operation of all of said monitoring means, the end of each of said synchronizing pulses defining the start of a time slot and a number of said synchronizing pulses defining the number of time slots, and means for preselecting the number of synchronizing pulses to define a separate time slot for each of said monitoring means and at least one further time slot which is assigned to said control means, and at least one area control means connected in an area loop with certain ones of said monitoring means, said area control means also being connected in said common loop to receive said synchronizing signal and to responsively provide a further synchronizing signal for associated monitoring means to effect the generation of information signals by the associated monitoring means and for relaying information signals provided by associated monitoring means to said common loop for transmission over said common loop to said control location.

16. A system as set forth in claim 15 wherein said area control means includes area synchronizing means for generating a further plurality of synchronizing pulses which comprise said further synchronizing signal for defining a predetermined number of time slots including a separate time slot for each of the monitoring means connected to said area loop and a time slot assigned to said area control means.

17. A system as set forth in claim 16 wherein each of said monitoring means connected to said area loop includes means responsive to a different one of said further synchronizing pulses to provide an information signal during an assigned time slot.

18. A system as set forth in claim 15 wherein said area control means includes pulse counting means operable to count out a group of the synchronizing pulses transmitted over said common line and means controlled by said pulse counting means to provide a plurality of synchronizing pulses corresponding in number to the synchronizing pulses of said group for transmission over said area loop to effect the generation of information signals by the monitoring means connected thereto.

19. A system as set forth in claim 16 wherein said area synchronizing means includes pulse counting means for counting the synchronizing pulses transmitted over said common loop, pulse generating means operable when enabled to generate further synchronizing pulses for transmission over said area loop to enable the monitoring means connected thereto, and enabling means controlled by said pulse counting means to enable said pulse generating means when a first preselected number of said synchronizing pulses have been counted and for disabling said pulse generating means after a further preselected number of synchronizing pulses have been counted.

20. A system as set forth in claim 19 wherein said pulse counting means includes pulse detecting means connected to said common loop for detecting said synchronizing pulses and providing a control signal for each synchronizing pulse detected, and counter means for counting the number of control signals provided by said pulse detecting means.

21. A system as set forth in claim 20 wherein said pulse detecting means includes first monostable circuit means enabled by each synchronizing pulse to provide an output signal of a preselected duration and second monostable circuit means enabled by the output signal provided by said first monostable circuit means to provide said control signal.

22. A system as set forth in claim 20 wherein said pulse detecting means includes first monostable circuit means enabled by each synchronizing pulse to provide an output signal for approximately the duration of the synchronizing pulse and the time slot defined by the synchronizing pulse, and second monostable circuit means enabled by the output signal provided by said first monostable circuit means to provide said control signal.

23. A system as set forth in claim 17 wherein said area synchronizing means includes continuity testing means enabled during the time slot assigned to said area control means to test the continuity of said area loop.

24. A system as set forth in claim 23 wherein said area control means includes response generating means enabled by said continuity testing means to provide an information signal during the time slot assigned to said area control means whenever said area loop is continuous.

25. A system as set forth in claim 24 wherein said area control means further includes amplifier means for extending the information signals provided by said response generating means and by the monitoring means connected to said area loop to said common loop for transmission over said common loop to said control location.

26. A system as set forth in claim 24 wherein said continuity testing means includes means for inhibiting said response generating means whenever said area loop is discontinuous to thereby prevent the generation of said response signal during the time slot assigned to said area control means.

27. A system as set forth in claim 21 including a plurality of area control means each connected in said common loop and each being connected in a separate area loop with a different group of said monitoring means, different area control means being operable to control the operation of the associated group of monitoring means at different times.

28. In a communication system for reporting information from a plurality of remote locations to a control location over a common communication channel, monitoring means at each of said remote locations opeRable when enabled to provide an information signal representing the condition of at least one variable monitored by said monitoring means, at least one area control means connected in an area loop with at least one of said monitoring means and operable when enabled to generate a synchronizing signal for enabling said one monitoring means, at least one local control means connected in a local loop with said area control means and operable when enabled to generate a further synchronizing signal for controlling the operation of said area control means, said local control means also being connected to said common communication channel, and master control means for generating a master synchronizing signal for transmission over said communication channel to enable said local control means.

29. A system as set forth in claim 28 wherein each of said monitoring means is enabled to provide said information signal during a different preassigned time slot, said master control means including time slot rate generating means for providing a master synchronization signal at a predetermined frequency, said local control means being responsive to said master synchronizing signal to generate said further synchronizing signal which defines a plurality of time slots, said area control means being enabled during certain ones of said plurality of time slots to provide said synchronizing signal for enabling at least said one monitoring means.

30. A system as set forth in claim 29 wherein said area control means includes means responsive to said further synchronizing signal to generate a plurality of synchronizing pulses for transmission over said area loop during said certain ones of said time slots, each of said synchronizing pulses defining a separate time slot, different ones of said monitoring means being enabled during a different one of said time slots to provide an information signal.

31. In a communication system for reporting information from a plurality of remote locations to a control location over a common transmission line, a normally unpowered monitoring means at each of said remote monitoring locations, each of said monitoring means including power circuit means, pulse counting means and response generating means operable when energized to provide a response signal representing the condition of at least one variable monitored by said monitoring means for transmission over said transmission line to said control location, and control means at said control location for generating a plurality of address pulses for transmission over said transmission line to the remote locations for supplying power to each of said monitoring means and for effecting sequential readout of the monitoring means, the end of each address pulse defining the start of a time slot and the number of address pulses defining the number of time slots, the power circuit means of each monitoring means being responsive to a first one of said address pulses to provide an energizing signal for enabling said pulse counting means to count further ones of said address pulses, the pulse counting means of different ones of said monitoring means being responsive to a different number of address pulses to extend said energizing signal to an associated response signal generating means to enable a response signal to be provided whereby response signals are provided by different ones of said monitoring means during a different preassigned time slot.

32. In a communication system for reporting information, including normal and off-normal conditions for a plurality of variables, from at least one remote location to a control location over a communication channel, monitoring means at said remote location including initiating means having a plurality of condition sensing means each of which indicates a normal or an off-normal condition for a different one of the variables, and response generating means operable when energized to normally generate a response signal at a first frequency indicative of a normal condition for all of thE variables, said response generating means being selectively controllable by said initiating means in the event of an off-normal condition for one or more of the variables to generate a response signal at a different frequency, and means for coupling the response signal to said communication channel for transmission to said control location.

33. A system as set forth in claim 32 including control means at said control location for generating an enabling signal for transmission over said communication channel to said monitoring means at said remote location to effect energization of said response generating means.

34. A system as set forth in claim 33 wherein said monitoring means is normally unpowered, said monitoring means further including power circuit means responsive to said enabling signal for deriving a power signal from said enabling signal and means for extending said power signal to said response generating means for energizing said response generating means to provide a response signal.

35. A system as set forth in claim 32 wherein said response generating means includes priority means for assigning priorities to each of the variables to permit the condition of the highest priority variable to be transmitted to the control location whenever more than one variable is off-normal simultaneously.

36. A system as set forth in claim 35 wherein said initiating means includes first condition sensing means, second condition sensing means and third condition sensing means, said response generating means including priority means for assigning priorities to said first, second and third sensing means to permit an indication of an off-normal condition for said first condition sensing means to be transmitted prior to off-normal conditions for said second or third condition sensing means whenever an off-normal condition is indicated by more than one of said condition sensing means.

37. A system as set forth in claim 35 wherein said response generating means includes multifrequency signal generating means selectively operable to generate a response signal at one of a plurality of frequencies including said first frequency and a plurality of further frequencies which include a different frequency for each of the monitored variables.

38. A system as set forth in claim 37 wherein said initiating means includes a plurality of conductor means for connecting said condition indicating means to said response generating means, said response generating means further including means enabled whenever one of said conductor means is discontinuous to inhibit the operation of said signal generating means.

39. A system as set forth in claim 37 wherein said control means includes receiver means for receiving the response signal provided by said monitoring means, said receiver means including a plurality of frequency detecting means having a separate frequency detecting means for each frequency provided by said response signal generating means, each frequency detecting means being normally operable to provide a first output signal, and enabled to provide a second output signal whenever a response signal at the corresponding frequency is received by said receiver means and exclusivity circuit means controlled by the output signals provided by all of said frequency detecting means to provide an error signal whenever two or more of said frequency detecting means provide said second output signal simultaneously.

40. A system as set forth in claim 39 wherein said receiver means includes strobe pulse generating means enabled by said enabling signal to provide at least one strobe signal for permitting the outputs of said frequency detecting means to be extended to said exclusivity circuit means at a predetermined time relative to the termination of said enabling signal.

41. A system as set forth in claim 40 wherein said exclusivity circuit means is enabled by said strobe signal to provide an error signal whenever at least one of said frequency detecting circuits fails to provide a secoNd output signal at the time a second strobe signal is provided.

42. In a communication system for reporting information from a plurality of remote locations to a control location over a common communication channel, monitoring means at each remote location for monitoring the condition of a plurality of variables, said monitoring means including response signal generating means selectivity operable when enabled to generate a response signal at one of a plurality of frequencies, a first one of said frequencies representing a normal condition for all of said variables and different ones of said other frequencies representing an off-normal condition for different ones of said variables, control means at said control location including receiver means and synchronizing means for generating a synchronizing signal for transmission over said communication channel to said remote locations to enable the response generating means of different ones of said monitoring means to provide a response signal for transmission over said common communication channel to said receiver means at said control location.

43. A system as set forth in claim 42 wherein said synchronizing means includes means for generating a plurality of synchronizing pulses which comprise said synchronizing signal, the end of each of said synchronizing pulses defining the start of a time slot, and the number of said synchronizing pulses defining the number of time slots, different ones of said response generating means being enabled to provide a response signal during a different preassigned one of said time slots.

44. A system as set forth in claim 42 wherein said receiver means includes a plurality of detecting means, including a separate frequency detector means corresponding to each one of said plurality of frequencies, said frequency detector means being selectively enabled in accordance with the frequency of the response signal provided by a given one of said monitoring means to provide an output signal indicating the condition of the variables monitored by said one monitoring means.

45. A system as set forth in claim 44 wherein each said frequency detector means comprises a phase locked synchronous detector means.

46. A system as set forth in claim 44 wherein said receiver means includes exclusivity logic circuit means including signal output means and signal processing means for extending the output signals provided by said frequency detector means to said signal output means, said signal output means being operable when enabled to provide an output signal representing the conditions of the monitored variables for a given one of said monitoring means only after an output signal has been provided by one of said frequency detector means for a predetermined time during the time slot assigned to such monitoring means.

47. A system as set forth in claim 46 wherein said receiver means includes strobe signal generating means enabled by the one of the synchronizing pulses which defines the time slot for said one monitoring means to provide at least one strobe signal for enabling said signal output means at a predetermined time during the time slot for said one monitoring means.

48. A system as set forth in claim 47 wherein said strobe signal generating means includes first monostable circuit means enabled by said one synchronizing pulse to provide a control output for a predetermined duration, and second monostable circuit means responsive to said control output to provide said strobe signal at said predetermined time.

49. A system as set forth in claim 47 wherein said exclusivity logic circuit means further includes inhibit means controlled by the output signals provided by said frequency detector means to provide an error output signal over said signal output means whenever at least one of said frequency detector means fails to provide an output signal during said predetermined time.

50. A system as set forth in claim 49 wherein said receiver means further includes error counting means for providing An error indication only after a predetermined number of error output signals have been provided by said inhibit means.

51. A system as set forth in claim 49 wherein said synchronizing means is continuously operable to generate said plurality of synchronizing pulses to provide repetitive scans of said monitoring means and wherein said error counting means includes accumulating means for accumulating a count of error output signals provided during successive scans.

52. A system as set forth in claim 51 wherein said receiver means includes scan reset means operable to reset said accmulating means whenever said inhibit means fails to provide an error output signal during a given scan.

53. A system as set forth in claim 43 wherein the condition of the variables monitored by each monitoring means is represented by a single frequency which is provided during the preassigned time slot, and wherein a change of state of a given variable is indicated by a change from one frequency of said plurality of frequencies to another frequency of said plurality of frequencies.

54. A current pulse generator responsive to low level signals to provide high power current pulses comprising operational transconductance amplifier means having a first input connected to a source of low level signals, a second input connected to a point of reference potential, and capacitor means connected to an output of said amplifier means, said amplifier means being responsive to each low level signal extended thereto to provide output current for causing said capacitor means to charge at a first rate and to discharge at a second rate to thereby provide a high power current pulse having different rise and fall times.

55. A current pulse generator as set forth in claim 54 which includes means for supplying control current to said amplifier means for controlling the charge and discharge rate of said capacitor means to provide a high power current pulse having a substantially linear rise time and a non-linear fall time.

56. A current pulse generator responsive to low level signals to provide high power current pulses comprising operational transconductance amplifier means having a first input connected to a source of low level signals, a second input connected to a point of reference potential, capacitor means connected to an output of said amplifier means, bias means connected to a bias input of said amplifier means to supply current to said amplifier means for establishing an output current level for said amplifier means, said amplifier means being responsive to each low level signal extended to said first input to provide output current for effecting charging and discharging of said capacitor means, and control means connected to a control input of said amplifier means to supply further current to said amplifier means to cause said capacitor means to charge at a first rate and to discharge at a second rate to provide a current pulse having different rise and fall times.

57. A current pulse generator as set forth in claim 56 wherein said control means causes said capacitor means to charge at a substantially linear rate and to discharge at a non-linear rate.