Information transmission system

• US 4,864,519 A
• Filed: 09/08/1988
• Issued: 09/05/1989
• Est. Priority Date: 12/18/1984
• Status: Expired due to Term

• Current Assignee: Gent Ltd. (Honeywell International Inc.)
• Original Assignee: Gent Ltd. (Honeywell International Inc.)
• Inventors: Johnson, Duncan M., Appleby, David
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Mattson, Brian M.
• Application Number:
  US07/241,775
• Time in Patent Office: 362 Days
• Field of Search: 364/505, 364/506, 364/550, 364/557, 364/481, 364/138, 364/140, 364/141, 364/148, 364/152, 364/579, 364/580, 364/200, 364/900, 340/577-579, 340/506, 340/508, 340/825.36, 340/825.05
• US Class Current: 700/292
• CPC Class Codes: G08B 25/003 Address allocation methods and details
• CPC Class Codes: G08B 26/005 with substations connected in series, e.g. cascade

Abstract

A driving device forming part of a controller is connected in a circuit and supplies power to a number of stations in the circuit. Each station has a microcomputer and at least one sensor capable of detecting a significant event of interest. Each microcomputer monitors its adjacent circuit, stores information derived from any sensor in its station and periodically informs the controller. The stations each have at least one circuit breaker controlled by its microcomputer for isolating that station from an adjacent station. The controller interrogates all the stations to identify any station at which an event has occurred and receives, stores, and analyzes data from the microcomputers and sends instructions thereto.

Claims

1. An information transmission system comprising

a plurality of sensors for the conversion of respective physical parameters to respective electrical signals,

a circuit connected to a driving device which supplies power via said circuit to energize the sensors, said circuit incorporating a plurality of circuit breakers connected in series in said circuit between respective parts of said circuit, each said circuit breaker acting to isolate at least one respective one of said parts of said circuit from an adjacent one of said parts,

a plurality of stations connected in parallel with one another to said circuit, so that each said station is adjacent at least one other one of said stations along said circuit, each said station incorporating a microcomputer, at least one of said circuit breakers and at least one of said sensors,

each said microcomputer periodically monitoring at least one respective one of said parts of said circuit adjacent its respective station, and monitoring, interpreting and storing information derived from said at least one sensor incorporated in that station, for determining from that information if an event has been detected by said at least one sensor at that station,

said microcomputer at each said station controlling each said circuit breaker therein, for creating at least one open circuit between respective adjacent ones of said parts of the circuit operationally, to isolate that station from at least one adjacent one of said stations, respectively, and

a controller incorporating said driving device being arranged to interrogate all of said stations to identify any one thereof at which one of said events has occurred, to analyze data relating to each such event, and to generate and send instructing signals to said microcomputer of each respective station concerning the respective sensed event.

2. A system according to claim 1, in which each said station in said circuit has a common address, and said controller comprises addressing means for allocating a unique primary address to each said station in said circuit.

3. A system according to claim 2, in which said addressing means is operable to allocate a unique group address to at least one selected group of said stations, said at least one selected group selectively including all of said stations.

4. A system according to claim 3, in which said addressing means is operable to allocate a plurality of said unique group addresses to respective groups of said stations, wherein each said station can be selectively included in at least two of said groups by allocation thereto of the at least two respective unique group addresses.

5. A system according to claim 4, in which said circuit incorporates a T-junction in at least one of said stations, each said station with at least one of said T-junctions incorporating at least two of said circuit breakers, each said circuit breaker of each said station with at least one of said T-junctions operating for selectively breaking at least one respective one of two of said parts of the circuit operationally, to isolate that station from a respective adjacent one of said stations if the microcomputer at that station detects a fault in that part.

6. A system according to claim 2, comprising a respective means at each said station, for permitting a first of said stations in said circuit to receive power from and communicate with said controller when its circuit breaker is open, and for permitting any other one of said stations in said circuit to receive power from and communicate with the said controller when each said circuit breaker of said other station is open and at least one respective circuit breaker of each of every one of all said stations between said controller and said other station are closed.

7. A system according to claim 6, in which said addressing means is operable firstly to allocate a primary address to any first station in said circuit, to elicit an acknowledging response from said first station, and to thereafter instruct said first station to close one of said at least one a circuit breaker thereof, wherein said addressing means is then enabled to communicate with and allocate primary addresses successively to others of said stations in the circuit, each said primary address providing unique identification of the respective station.

8. A system according to claim 7, in which, prior to the allocation of each said primary address, said addressing means sends a signal to the respective one of said stations, said signal including one of said common addresses, in order to elicit from said respective station an acknowledging response to said signal with the common address.

9. A system according to claim 7, said means at each said station being operable, after said allocation of a primary address to that station and prior to the allocation of a primary address to the next station, to send a signal to the controller confirming the allocation of that primary address to that station.

10. A system according to claim 7, in which each said said acknowledging response elicited determines that only the respective station has been allocated the respectivve primary address, by comparing the voltage at said respective parts of said circuit at each side of said at least one circuit breaker of said station.

11. A system according to claim 10, in which said microcomputer of each said station incorporating one of said sensors with an analog signal has a plurality of analog channels, each said channel being programable to perform a regular analog-to-ditial conversion and having a programable threshold, said controller is operable on start-up to allocate a conversion rate and a threshold value to each channel and thereafter is operable to request the digital value of selected conversions on a channel by channel basis, and each said digital value having being stored in the station microcomputer as a reference values associated with the respective channel.

12. A system according to claim 2, in which said controller is programmed to determine if one of said events has occurred at any one or more of said stations by a fast search routine that repeatedly addresses all the stations with a combination of a common address and a successively different selected numerical command, the microcomputer of each station being programmed to respond only (1) if at least one of said events has occurred as determined with its at least one respective detector and (2) if a predetermined result is obtained from a predetermined logic comparison by the microcomputer between each respective one of said different selected numerical commands and said primary address of that station.

13. A system according to claim 12, in which the microcomputer of each said station is programmed to recognise each respective one of said events at a respective one of more than one level of priority, and the controller is programmed so that the fast search routine identifies the stations in order of event priority.

14. A system according to claim 1, in which said circuit is a two-wire circuit comprising two wires, each said station being connected across said two wires, and each said circuit breaker and each said part of said circuit is comprised in a first of said two wires of said two-wire circuit.

15. A system according to claim 1, in which said circuit includes at least one T-junction, each said T-junction being at a respective one of said stations at which said circuit divides to further connect to two respective ones of said adjacent stations, each said station at each said T-junction incorporating at least two of said circuit breakers for selectively disconnecting each of at least two respective ones of said parts of the circuit operationally from a further respective one of said parts of said circuit, to isolate that station from at least one of said two adjacent stations if the microcomputer at that station detects a fault corresponding to a respective one of said at least two parts.

16. A system according to claim 1, comprising

a least predetermined ones of said sensor outputting respective analog signals,

said microcomputer of each respective one of said stations including at least one respective analog channel programmable to perform a regular analog-to-digital conversion from said analog signal output from the respective sensor therein, each said channel having a respective programmable threshold, and

means in said controller operable on start-up to allocate a conversation rate and a threshold value to each said channel, and thereafter operable to request a respective digital value of selected ones of said analog-to-digital conversions on a channel by channel basis, each said value being stored in said microcomputer of the respective station as a reference value associated with the respective channel.

17. A system according to claim 16, in which the analog output of each respective sensor continues to be monitored by the station microcomputer at the conversion rate and a predetermined intervals, each value thereof being compared with the respective stored reference value, wherein if the absolute difference between said values is not less than the respective programmed threshold, indicating that one of said events may have occurred at the station, this is registered by the controller upon its next interrogation of the station.

18. A system according to claim 16, in which the microcomputer of each said station has a buffer memory associated with said at least one analog-to-digital conversion channels thereof, wherein the values of the conversions thereon are stored in digital form, the oldest stored values being lost from said buffer memory as the newest value is written into it, so that the controller has access to a series of readings immediately proceeding and immediately following detection of each said event.

19. A system according to claim 1, in which during regular interrogation of the respective ones of said parts of said circuit by said stations the length of time that any signal different from a predetermined signal exists in a respective part of said circuit is monitored to determine if a short circuit fault has occurred, and after detection of any short circuit fault by all of said stations the circuit breakers of all of said stations are opened and then upon initiation by said controller are successively closed, the effect of each closure at each said station being monitored by the microcomputer of that station, until the station adjacent the fault is reached when its circuit breaker is opened to isolate the fault.

20. A system according to claim 1, in which said controller supplies power to said circuit in a selected number of states, one of said states being a high current state during which said controller sends signals to said stations, and a one of said states of said controller being such that it supplies current to each respective one of said stations via said circuit from a negative resistance source, said further state being used by said controller to receive signals from said stations.

21. A system according to claim 1, in which the circuit includes at least one loop having each of two endsconnected to a separate respective driving device comprised in said controller, to permit each said loop to be selectively energized from each end thereof.

22. An information transmission system comprising:

a circuit,

a plurality of stations connected in parallel with one another in said circuit,

at least one sensor in each said station to convert a respective physical parameter at each said station to a respective electrical signal,

a controller connected to said circuit, said controller including a driving device to supply power via said circuit to energize said sensors,

at least one circuit breaker in each of at least two of said stations, each said circuit breaker of each said station being connected in series in said circuit for breaking a respective part of the circuit to isolate that part from an adjacent part of said circuit, and

a microcomputer comprised in each said station and powered from said controller via said circuit, said microcomputer controlling at least one of said circuit breakers in its respective station,

wherein;

said microcomputer in each said station is arranged periodically to monitor, interpret and store information derived from each respective sensor in that station, and to determine from said information if a significant event has been detected by said sensor;

said controller is arranged to interrogate all of said stations to identify each one of said stations at which a significant event has occurred, to analyze data relating to each such event and to generate and send corresponding instruction signals to said microcomputers in all of said stations; and

said microcomputers in all of said stations periodically monitor a respective one of said parts of said circuit adjacent to the respective station and, upon detecting a condition characteristic of a short-circuit fault, open each said circuit breaker of the respective station which, upon initiation by the driving device, are then successively closed by their associated microcomputers until the fault is reached, whereupon the most recent one of said circuit breakers is closed is reopened by its associated microcomputer to isolate said short-circuit fault.