GB2262682A - Remote meter reading system - Google Patents

Abstract

A system for remotely reading a gas or water meter in say a house 2 or other premises. A gas or water meter 3 is housed in a pit 4 adjacent the curtileges of those premises 2, there being an encoder means 5 forming an integral part of the meter 3. The encoder means 5 essentially converts fluid flow data from the meter 3 into electronic format. There is also in the pit 4 a meter interface unit 6 which conducts the electronic data via a suitable connection to PSTN 7 (Public Switched Telephone Network). Once in the PSTN 7, the electronic data is transferred to a utility remote metering centre 9 and a remote maintenance centre 10. There is also at the premises 2 a device in the form of a manually operable display device 11 whereby information encoded by the encoder 5 and interface unit 6 can be accessed by the consumer. The display device 11 may be battery powered and may incorporate a power-saving circuit. <IMAGE>

Description

LSCESS SYSIEM The invention relates to an access system, particularly to a system of accessing a volume of fluid flowing through a meter, for example a water meter or gas meter.

One of the problems of reading water consumption data, particularly for domestic consumers, is that ideally a meter should be situated inside the house, or at least as closely adjacent the curtilages of the consumer's premises. This is to obviate misreadings because of leakage. On the other hand, if the meter is within the house, access has to be gained thereto in order to take a reading, and this is not always convenient. Alternatively, if the meter is in a pit on public property, nevertheless personnel still have to go to the pit, raise a lid thereof etc., and gain access, which can cause a nuisance, as well as being expensive.

It is accordingly an object of the invention to seek to mitigate these disadvantages.

According to one aspect of the invention there is provided a system of accessing a volume of fluid passing through a meter, cam- prising means to convert a fluid flow into electronic information, a remote means to interrogate and/or access and store the electronic information, means to communicate the converter and remote means, and means adjacent the converter to provide local information concerning the amount of information collected by the converter.

The communication means may comprise a public telephone network, which may include a radio telephone link.

According to a second aspect of the invention there is provided a device for displaying information, a source thereof, comprising a circuit including a visual display, means for providing power, and a manual actuator whereby the device is actuated to display information in the source.

The source may comprise a means to convert fluid flow into an electronic form and communicate said information with a remote location, the converter comprising electronic accessing and connection means whereby the device can access the source.

The power means may comprise a battery, preferably two batteries.

The manual actuator may comprise a push button.

Using the invention it is possible to provide a system for reading a domestic utility meter such as a water meter or gas meter.

A system of domestic water meter reading embodying the invention is hereinafter described, by way of example, with reference to the accompanying drawings.

Fig 1 shows schematically the system according to the invention; Figs 2 and 3 show respectively a microprocessor and block diagram of a micrcprocessor of a display device of the invention.

Referring to the drawings, there is shown schematically in Fig 1 a house 2, or subscriber's premises. A water meter 3 is housed in a pit 4 adjacent the curtileges of those premises 2, there being an encoder means 5 forming an integral part of the meter 3. The encoder means 5 essentially converts fluid flow data from the meter 3 into electronic format. There is also in the pit 4 a meter interface unit 6 which conducts the electronic data via a suitable connection to PSTN 7 (Public Switched Telephone Network). Once in the PSTN 7, the electronic information is transferred through a meter reading access circuit post 8 to a utility terminal unit 9 and remote maintenance centre 10.

There is also at the premises 2 a device in the form of a manually operable display device 11 whereby information encoded by the encoder 5 and interface unit 6 can be accessed by the consumer.

Incidentally, it will be understood that more than one meter or kind of meter may be accessed via the unit 6, as shown at 12 in the Fig 1.

The display device 11 provides the consumer with an easy access meter reading capability from within the premises. The main features of the unit 11 centre around a clear, large character display. Having the ability to read the meter encoder 5, on demand also requires unit 11 to be capable of powering the unit 6 as well as itself. The source of this power comes from two batteries located within an enclosure or housing of the unit 11, these being the customer's responsibility to replace when discharged. A single push button allows the read and display cycle to commence and there is a timed interlock to minimise the "ON" time of the units 5, 6 and 11. The device 11 is installed within the custormer's premises and is connected to the system using a multicore cable.

The housing of the device 11 comprises a standard domestic mains meter box dimensions. Both flush mounting, via metal back boxes, and surface mounting embodiments are, it will be understood, envisaged. This provides for the installation of flush mounting device 11 in new houses or where such installation is deemed more appropriate.

The device 11 has three prime assemblies, namely a front panel, a PCB enclosure or back box, and a mounting box. A single printed, wipe clean semi-transparent front sheet finishes the assembly.

Battery replacement is undertaken by the removal of the two escutcheon screws and on pulling the front panel out of its mounting box. The use of screw attachment for the battery and wiring access is mandatory for any equipment electrically coupled to PSTN approved equipment. Both the front panel and mounting box are proprietary units requiring minor machining work. The back box is made of a suitable material such as ABS either in vacuum or injection mould form.

Two PCB's are incorporated within the housing of the device 11. The main PCB contains all the major logic devices including the microcontroller, memory and display. This PCB is immediately located behind the front panel. The rear, smaller PCB is located within a protrusion in the back box adjacent to the batteries. This PCB houses the wiring terminal block, power supply and communications circuitry. Connection between the two is via flexi-strip.

After installation and the fitting of two fresh "PP3" batteries, which are alkaline manganese cell batteries and are replacable, the device 11 can access the encoder 5 and retrieve the meter reading.

On manual depression of the single control button the device 11 commences operation. Initially, the internal power regulators are activated, which in turn powers up the microcontroller of the device 11 and the local interface 6. The microcontroller electrically interlocks the push-button allowing the customer to release the button. At this point the display indicates a "WAIT" activity and remains in this state until the interface 6returns the meter data. The microcontroller monitors the dedicated camnunications lines between itself and its local interface 6 and commences data decoding. After all data is received, interrogated and validated the meter reading data is displayed on an LCD of the display of the device 6. The reading remains for a period of 10 seconds (approximately) after which time the device 11 down-powers automatically.

Failure to adequately communicate with the local interface 6 results in the word "ERROR" being displayed on the screen. An associated number will be included should the error be catastrophic. In this way, minor errors are just indicated by the word "ERROR" whilst, where possible, serious faults indicate an error message including a number between 1 and 9. These error messages provide a first line fault analysis and are reported by the customer.

The device 11 has as indicated, a microprocessor 13 as the core element. The control processor element U1 comprises an 80C39 microcontroller device having internal RAM. The device features a rtulti- plexed low byte Address and Data bus. Latch U2 separates the low Address byte and this plys, high order Address bits feed the EPROM U3. Data from the EPROM is accessed directly by the microcontroller and appears on lines DO - D7. The microcontroller is controlled by a crystal oscillator circuit comprising X , C and C and operates at 6 MHz. At the time of powering, a delayed reset circuit using components D , R and C ensures the proper processor initialisation.

The microcontroller has usable I/O pins which under software control can be programed as required. All display and, ancillary control functions are connected to these I/O pins allowing the software to exercise maximum control and flexibility.

All components are CMOS and as such consume minimum power during operation. The clock frequency of 6 MFbc is a compromise between operational software speed and power consumption.

The device 11 is as described battery powered, specifically from two series connected PP3 batteries. In order to operate over a reasonable period of time the power control circuitry of the device 11 functions as a current source. Considering the total power demand on the batteries, it will be understood that when energised the device 11 powers the interface 6, the meter encoder 5 and itself. The total current drawn by the interface 6 and encoder block is approximately 20 mA (maximum 25 mA). The device 11 draws approximately 8 mA on its own. Voltage factors occur at the interface 6 power terminals in so far as 12 Volts must be available for full interface 6 operations. Allowing for 1 V to be dropped over the cabling between the device 11 and the interface 6 requires 13 V terminal voltage to be available at the CDU.

Because the distance between the members 6 and 11 will vary from site to site it is clear that the line losses will also vary. For this reason the power supply operates as a current source having the ability to generate a constant current of 33 mA. This ensure that the series voltage drop is very small, thus allowing a reasonable span of battery voltages. Taking all these parameters into account equates to an end point total battery voltage of approximately 14 V or, 7 V for each battery. This gives a total, typical battery life of five hours. Equating this parameter to typical usage indicates the following, typical battery life: a) If the device 11 is used once every day for one year, the battery hours used = one hour.

b) If the device 11 is used four times per month for one year, the battery hours used = eight minutes.

The battery shelf life is the determining factor in battery life rather than usage of the system.

The current regulator is formed around Q1, Q2 and associated components. when the energise button is depressed current is drawn from the battery via R3, R2, D7 and D8. Base current through Q1 causes that device to begin conducting. Owing to the action of D7 and D8 the voltage between the base of Q1 and the battery positive vail is clamped at approximately 1.3 V. Of this Ql's base emitter junction will clamp 0.7 V, leaving 0.6 V across R31. This fixed voltage acros R31 therefore causes a constant current to flow through Ql's collector, The value of R31 is selected for the required current flow where I = 0.7/R31. Elements Q2, R4 and R5 provide a button interlock circuit controlled by the microcontroller. Local device 11 regulation is provided by the series regulator comprising R30 and D2.

To give warning of the need for battery replacement a comparator circuit is employed which feeds the microcontroller, U4B configured as a comparator compares the power rail of the interface 6 with a reference voltage. The reference used is the +5 V CDU supply. The output of the comparator drive Q3 conditions the signal for microcontroller use. Hysteresis is provided by positive feedback via R26. When battery Volts are satisfactory the output of U4B is positive and Q3 is "on". This sets the reference point at pin 6 of U4B at 5.05 V. Resistors R23, R24 and R28 devide the interface 6 power rail such that the comparator switching point, 5.0v V, is reached when the interface 6 power rail is at 13 V. At this point the collector of Q3 rises to VOC indicating the low battery state.

Current loop data communications from the interface 6 is terminated by resistor R7. This allows bi-directional current to flow and R7 converts this current to a voltage, the polarity of which is determined by the current direction. Amplifier U4A is configured as a differential amplifier of unity gain reference to 3,5 V by resistor ladder Rll, R12, R13 and R22. The resistor chain also provides two further reference voltages of 4.89 and 2.33 V. Comparator U5A com- pares the amplified signal of U4A with the higher, 4.89 V, reference and if the amplified signal is greater the output of U5A is at zero Volts. The same occurs with U5B but using the lower 8, 2.33 V reference, In this way, positive currents of sufficient magnitude are detected by U5B. The result of the offset rererences used gives noise immunity to the sytem as equivalent currents of greater than +/- 0.3 mA must flow through R7 before data detection will occur.

Two sets of detectors are used to generate more information concerning the state of the data link than could be achieved with a single line. These "extra" states are used to indicate error conditions on the line.

Element U7 is a tri-plexed LCD display controller device which interfaces directly to the microcontroller. It contains all necessary control circuitry to drive the selected 6 digit multiplexed LCD display. The processor writes individual digit data into dedicated registers within U7. The multiplexing requirements of LCD displays is complex in nature, due to their need to be supplied with a.c.

voltages. All phased voltages necessary are generated within U7 allowing the simplified configuration adopted. LCD display contrast is a function of the amplitude of the a.c. voltage applied to the segments and this is set by diodes D2 and D6 and R29. The voltage selected for this application is 5.1 - (5 x 0.6) = 2.1 V.

The interface 6 is part of the automatic meter reading access system 1. It is located in close proximity to the consumer's water meter and is used to read data from the meter 3, following reception of a specific tone sequence. After the data is read, the interface 6 formats the data and sends it to the meter reading access circuit (MAC) located in the telephone exchange local to the consumer, using the consumer's existing telephone line. Normal telephone usage is not affected.

The information gathered by the NRAC equipment is transferred by modem to the unit 9 which acts as the data gathering centre and is used for display and archiving purposes.

The unit 9 stores a file which correlates to the consumer's telephone number and other information with a unique customer account number. During a meter reading operation, this file is accessed to send each subscriber's telephone number in succession to the MRAC in order to read each meter. The unit 9 accumulates the meter readings as they are received and produces an output file of meter readings for further processing.

The interface 6 is conneced in parallel across the tip and ring telephone lines. During normal telephone use, the interface 11 appears as a very high impendance across the tip and ring pair, and is, therefore, transparent to normal telephone transmissions. All of the operating power of the interface 6 is drawn from the telephone line.

The interface 6 has an auxiliary port interface facility for driving the device 11 which enables the consumer to access the mater meter reading without looking into the meter pit.

This facility can "double" as a port for test purposes where meter information, line integrity and circuit performance can be accessed.

The MRAC is connected to the PSTN via the Telephone Test Trunk, which enables communication with respective interfaces 6 without disruption to the consumer S telephone usage. The onward transmission of collected water meter 3 data, is performed by normal modem or private circuits to the unit 9.

The main functions of the MRRC are to enable communication to take place between the unit 9 and the interface 6 located at the con sumer's premises and to perform meter reading cycles as instructed by the unit 9.

Connection through the telephone network to the interface 6 is achieved by connection of the MRAC to the British Telecom exchange test trunk. The test trunk is normally used for maintenance purposes and has the ability to connect to the subscriber's line without ringing the telephone. This gives the automatic meter reading system the ability to obtain water consumption data from the encoded meter 3 via the interface 6 using the consumer's existing telephone, without ringing tone being generated and more importantly, without intruding into the consumer's use of the telephone.

Following a command from the unit 9, the MRAC establishes connection to the interface 6 through the telephone exchange test trunk.

The MRA: then sends a special tone to the interface 6 which will be recognised by that interface as the initiation signal to commence a meter reading cycle.

Having read the meter consumption value of the encoder unit via the interface 6, the MRAC will pass the information back to the unit 9, thus completing the meter reading cycle for that consumer.

A function provided by the MRAC is the ability to "sum" usage data of the system 1. The MRAC can transmit this data over modem links to a computer system for collection at a central point.

The MRAC also has a maintenance capability, allowing remote access by, for example the unit 10 for the purpose of trouble-shooting and fault isolation of system 1 problems. Alarm indications are provided, indicating failure of the MRAC itself.

It will be understoood that the MRAC has a high level of security of communications on all its functions to prevent unauthorised access or tapering. The security includes ID numbers and callback security for all modem ports. A facility for changing ID and callback numbers is included.

MRAC units are situated in each telephone exchange covering the utility company's service area.

The unit 9 effectively comprises a "commend centre" function of the system 1 and includes at the telephone exchange local to the house 2 a circuit MRAC which is a meter reading access circuit. An IBM PC (or compatible) iwth disk storage, printer, a tape drive for data storage, a modem for communication through the telephone network and automatic meter reading software.

Located in the utility Company's central office, the unit 9 has the ability to carnunicate to the equipment deployed in the telephone exchange 7 local to the area served. The MRAC, having received its message from the unit 9, establishes a connection with the interface 6 as requested by the unit 9.

The software operating used enables the unit 9 automatically and sequentially to read all meters 3 within the utility Corrpany 'S supply area, by selecting the appropriate MRAC in the required meter reading schedule. A report will then be generated for each consumer.

Both the equipment and the interface 6 require security codes to be transmitted by the unit 6 prior to commencing communications. Each requires unique codes, which are retained within the database of the unit 8 and automatically transmitted, when access is actioned.

The unit 9 has three primary operating modes.

a) Database Entry Mode The function of this trode is to allow entry of data of all subscribers and MRAC units in the system. Also to allow database maintenance such as entry, modification and deletion of both subscriber and MRAC information.

b) Meter Reading Mode This mode allows the unit 9 to read the meter 3 connected to the system 1 in a number of ways: - unattended operation (automatically read all meters between certain hours of the day), - manual reading (user - initiated reading of one or more meters), - keyboard initiated automatic reading of some or all meters.

c) Report generation Mode Generation and printing of various reports.

It will be understood too that in addition to the above operating modes the system 1 provides database facilities for subscriber information, set-up parameters and meter readings.

Claims (8)

1. A system of accessing a volume of fluid passing through a meter, comprising means to convert a fluid flow into electronic information, a remote means to interrogate and/or access and store the electronic information, means to communicate the converter and remote means, and means adjacent the converter to provide local information concerning the amount of information collected by the converter.

2. A system as claimed in Claim 1, wherein the communication means comprises a public telephone network.

3. A system as claimed in Claim 2, wherein the public telephone network includes a radio telephone link.

4. A device for displaying information, a source thereof, comprising a circuit including a visual display, means for providing power, and a manual actuator whereby the device is actuated to display information in the source.

5. A device as claimed in Claim 4, comprising means to convert fluid flow into an electronic form and communicate said information with a remote location, the converter comprising electronic accessing and connection means whereby the device can access the source.

6. A device as claimed in Claim 4 or Claim 5, wherein the power providing means comprises a battery.

7. A device as claimed in Claim 6, wherein the power providing means comprises two batteries.

8. A device as claimed in any one of Claim 4 to 7, wherein the manual actuator comprises a push button.