Two and three wire utility data communications system

• US 5,243,338 A
• Filed: 06/23/1992
• Issued: 09/07/1993
• Est. Priority Date: 05/25/1990
• Status: Expired due to Term

• Current Assignee: Neptune Technology Group Incorporated (Roper Technologies, Inc.)
• Original Assignee: Schlumberger Industries Incorporated (Schlumberger NV)
• Inventors: Hamilton, David R., Wynn, Warren C. Jr., Brennan, William J. Jr.
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): GIUST, JOHN
• Application Number:
  US07/903,212
• Time in Patent Office: 441 Days
• Field of Search: 379/40, 379/100, 364/464.04, 364/465, 346/14 R, 346/14 MR, 324/103 R, 324/110, 324/113, 324/118, 324/153, 340/310 A, 340/310 R, 340/310 CP, 340/825.54, 340/825.56, 340/870.02, 340/870.03, 340/870.01
• US Class Current: 340/870.02
• CPC Class Codes: G01D 4/004 Remote reading of utility meters to a fixed location
• CPC Class Codes: G08C 17/04 using magnetically coupled devices
• CPC Class Codes: G08C 19/28 using pulse code
• CPC Class Codes: H04Q 2209/60 for transmitting utility meters data, i.e. transmission of data from the reader of the utility meter
• CPC Class Codes: H04Q 9/00 Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom
• CPC Class Codes: Y02B 90/20 Smart grids as enabling technology in buildings sector smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00
• CPC Class Codes: Y04S 20/30 Smart metering, e.g. specially adapted for remote reading

Abstract

A two wire/three wire utility data communications system for remotely reading utility meter registers. In the two wire version, a hand-held reading unit is inductively coupled over two wires via a port located remotely from a meter register. Alternatively, a meter interface unit (MIU) may be connected directly to the register via three wires. Each register includes one or more wheel position encoders. An AC interrogation signal is applied by the reading unit to encoder circuitry at the meter which powers the circuitry and causes the position of each encoder wheel to be read. In the two wire mode, register display information (e.g. the current meter reading) is transmitted back to the reading unit by varying the load (impedance) presented by the register side of the circuit. This causes a corresponding variation of the amount of current drawn from the reading unit. The current-modulated signal is decoded by the reading unit and converted into a register reading. The system can also operate in a three wire mode and read older fourteen wire encoded registers. Other features include remote programmability of register characteristics, the ability to interrogate multiple registers which share a common data bus, verification of encoder wheel positions before accepting a reading, real-time flow rate/leak detection, pulse output, and the capability of reading compound meters (i.e. meters having two registers to separately measure high/low flow rates).

Claims

1. A system for communicating with a measurement device over at least two wire lines, comprising:

a remote reader/programmer coupled to the lines, including means for generating an interrogate signal and means for storing a data signal; and

encoder means, responsive to a quantity of a commodity being measured by the measurement device and to the interrogate signal, for producing a modulated data signal indicative of the quantity and for communicating it to the remote reader/programmer via the lines, the reader/programmer storing the quantity indicative signal in the storage means;

the interrogate signal being modulated by the encoder means so as to vary the current flowing between the remote reader/programmer and the encoder means when the remote reader/programmer and encoder means are coupled via two wires, and the interrogate signal being used by the encoder means to generate a data signal whose, characteristics are varied when the remote reader/programmer and encoder means are coupled via at least three wires, so as to generate the modulated data signal.

2. The system of claim 1 wherein the remote reader/programmer and encoder means are inductively coupled over two wires and wherein the encoder means includes means for varying an impedance in accordance with data representing the measured quantity to cause the current flowing between the encoder means and the remote reader/programmer to be modulated in accordance with the data.

3. The system of claim 1 wherein the remote reader/programmer and encoder means are directly, electrically coupled over at least three wires, a first wire carrying clock signals generated by the reader/programmer, a second line carrying data signals from the encoder means, and a third line constituting electrical ground, the clock signals being applied by the reader/programmer to the encoder means as the interrogate signal, the encoder means including means for varying the characteristics of signals derived from the clock signals in accordance with data representing the measured quantity.

4. The system of claim 1 wherein at least two encoder means are coupled via the same wires to a reader/programmer, the reader/programmer including means for sequentially selecting and interrogating each of the encoder means.

5. The system of claim 4 wherein each the encoder means includes means for storing a series of data bits uniquely identifying the encoder means, and wherein the reader/programmer includes means for addressing each of the unique series of bits so as to poll all encoder means coupled to the lines.

6. The system of claim 5 wherein the series of data bits is indicative of a register select number different from data bits stored by the encoder means representing a register serial number.

7. The system of claim 5 wherein the reader/programmer includes means for polling all encoder means coupled to the lines until no further data signals are emitted by the encoder means.

8. The system of claim 4 wherein at least one encoder means further includes means for storing data bits indicative of the presence of at least an additional encoder means coupled to the at least one encoder means whereby when the reader/programmer polls the at least one encoder means the data bits indicative of the additional encoder means are read by the reader/programmer and, in response thereto, the reader/programmer addresses the additional encoder means.

9. The system of claim 1 wherein the interrogate signal uses pulse-burst length encoding of interrogate signal data transmitted from the reader/programmer to the encoder means.

10. The system of claim 9 wherein the interrogate signal data is binary encoded data with a binary "1" represented by a series of interrogate signal pulses of a first predetermined length, and a binary "0" represented by a series of interrogate signal pulses of a second predetermined length.

11. The system of claim 10, wherein a register reset signal is represented by a series of interrogate signal pulses of a length greater than the interrogate signal pulses representing either a binary "1" or a binary "0".

12. The system of claim 1 wherein the encoder means includes non-volatile memory means for storing data indicative of one or more characteristics of the measurement device with which it is associated.

13. The system of claim 12 wherein the characteristic data include a meter serial number, meter type, and data indicative of the presence of a further meter register.

14. The system of claim 12 wherein at least a portion of the memory means may be reprogrammed by means of a separate Programming signal generated by the reader/programmer and applied to the encoder means.

15. The system of claim 14 wherein the interrogate signal uses pulse-burst length encoding of interrogate signal data transmitted from the reader/interrogator to the encoder means.

16. The system of claim 15 wherein the interrogate signal data is binary encoded data with a binary "1" represented by a series of interrogate signal pulses of a first predetermined length, and a binary "0" represented by a series of interrogate signal pulses of a second predetermined length.

17. The system of claim 12 wherein the programming signal is a signal having a frequency different from the interrogate signal.

18. The system of claim 14 wherein the memory may be reprogrammed to include data indicative of a meter serial number, meter type, presence of a further meter register meter manufacturer, meter polling selection data, selection of two-wire or three-wire mode of operation, meter register resolution, data length, enable/disable pulse output, and a data checksum to enable data error detection of the contents of the memory.

19. The system of claim 14 wherein the reader/programmer includes means enabling a user to customize any programmable features, including data length, data format and type of data to be programmed.

20. The system of claim 14 wherein the memory means comprises an EEPROM and wherein the encoder means includes means for discriminating between the programming signal and the interrogate signal to place the encoder means in a programmable mode when the programming signal is detected whereby the contents of the EEPROM may be overwritten, and to place the encoder means in an interrogate mode when the interrogate signal is detected, whereby the contents of the EEPROM are read out and transmitted to the reader/programmer.

21. The system of claim 20 wherein the programming signal includes a unique initial series of data bits in response to which the EEPROM is enabled to allow the contents thereof to be overwritten.

22. The system of claim 20 wherein the programming signal includes data query bits in response to which the EEPROM transmits its stored contents to the reader/programmer.

23. The system of claim 1 wherein the measurement device includes a register having at least one display wheel for displaying the measured quantity and wherein the encoder means includes means for checking the position of the at least one register display wheel at least twice to ensure that the generated data signal is accurately indicative of the actual position of the register display wheel.

24. The system of claim 23 wherein the reader/programmer includes means for comparing at least a first and second reading of the register display wheel, and for generating an error indication if the readings do not match.

25. The system of claim 1 wherein the reader/programmer further includes means for communicating the modulated data signals to an external general purpose programmable data processor.

26. The system of claim 25 wherein the reader/programmer is programmable by means of the data processor.

27. The system of claim 26 wherein the reader/programmer is programmable to store information in the storage means indicative of meter locations, route information, meter serial number and type, and previous meter reading.

28. The system of claim 1 wherein the encoder means is connected to a communications port by the wires and the reader/programmer is portable and is powered by a battery, the reader/programmer further including a connector for temporarily mating with the communications port, the connector and port enabling communication between the reader/programmer and the encoder means.

29. The system of claim 1 wherein the encoder means is connected to a communications port by the wires and the reader/programmer is portable and is powered by a battery, the reader/programmer further including a connector for temporarily mating with the communications port, the connector and port enabling communication between the reader/programmer and the encoder means, and wherein the port comprises an inductive coil having two wires connected to the encoder means and the connector comprises a second inductive coil connected to the reader/programmer and adapted to be temporarily disposed proximate the port to enable communication between the reader/programmer and encoder means.

30. The system of claim 1 wherein the encoder means is connected to a communications port by the wires and the reader/programmer is portable and is powered by a battery, the reader/programmer further including a connector for temporarily mating with the communications port, the connector and port enabling communication between the reader/programmer and the encoder means, and wherein the port comprises a receptacle having at least three electrical contacts disposed therein and connected via at least three wires to the encoder means, the connector including at least three electrical contacts adapted to mate with the receptacle contacts when the connector is brought into contact with the port to enable communication between the reader/programmer and encoder means.

31. The system of claim 1 wherein the interrogation signal is the sole source of power for the encoder means.

32. The system of claim 1 wherein the encoder means comprises an absolute encoder coupled to a display register associated with the measurement device.

33. The system of claim 1 wherein the reader/programmer includes display means for displaying information represented by the modulated data signal.

34. The system of claim 1 wherein the reader/programmer includes means for decoding the modulated data signal and converting it to binary-encoded ASCII format.

35. The system of claim 1 wherein the measurement device includes means for producing switch closures at a rate proportional to a commodity being measured by the meter and the encoder means includes means for storing and transmitting data indicative of the switch closure rate to the reader/programmer in response to the interrogate signal.

36. The system of claim 1 wherein the measurement device includes means for producing switch closures at a rate proportional to a commodity being measured by the meter and the encoder means includes means for storing and transmitting data indicative of the switch closure rate to the reader/programmer in response to the interrogate signal, and wherein the reader/programmer and encoder means are inductively coupled to each other via two wires, the encoder means including means for generating data signals at two alternating and different frequencies indicative of the switch closure rate produced by the measurement device.

37. The system of claim 1 wherein the measurement device includes means for producing switch closures at a rate proportional to a commodity being measured by the meter and the encoder means includes means for storing and transmitting data indicative of the switch closure rate to the reader/programmer in response to the interrogate signal, and wherein the remote reader/programmer and encoder means are directly, electrically coupled over three wires, the encoder means including means for producing a data pulse upon the accumulation of a predetermined number of switch closures from the measurement device.

38. The system of claim 1 wherein the measurement device includes means for producing pulses at a rate proportional to a commodity being measured by the meter and the encoder means includes means for storing and transmitting data indicative of the pulses to the reader/programmer in response to the interrogate signal.

39. The system of claim 1 wherein the measurement device includes means for producing pulses at a rate proportional to a commodity being measured by the meter and the encoder means includes means for storing and transmitting data indicative of the pulses to the reader/programmer in response to the interrogate signal, and wherein the reader/programmer and encoder means are inductively coupled to each other via two wires, the encoder means including means for generating data signals at two alternating and different frequencies indicative of the rate of pulses produced by the measurement device.

40. The system of claim 1 wherein the measurement device includes means for producing pulses at a rate proportional to a commodity being measured by the meter and the encoder means includes means for storing and transmitting data indicative of the pulses to the reader/programmer in response to the interrogate signal, and wherein the remote reader/programmer and encoder means are directly, electrically coupled over three wires, the encoder means including means for producing a data pulse upon the reception of a predetermined number of pulses from the measurement device.

41. The system of claim 1 wherein the reader/programmer includes means for generating the interrogate signals for a predetermined time period in excess of the time required for the encoder means to respond thereto, and means for reading and storing data signals emitted by the encoder means in response to the interrogate signals, and further including means for comparing the data signals and for generating a signal representative of any difference therebetween over time and for generating a signal indicative of the time rate of change of a quantity represented by the data signals, whereby to give an indication of the rate of change of the quantity of a commodity being measured by the measurement device over the predetermined time period.

42. The system of claim 1 wherein the encoder means includes means for responding to the encoder means includes means for responding to the interrogate signal in a first manner and then automatically responding in a second manner.