United States Patent 19
`
`Jahret al.
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,707,852
`Nov. 17, 1987
`
`4,132,981
`4,315,251
`
`1/1979 White .....sesererersscererrees 340/870.02
`2/1982 Robinsonetal.............. 340/870.03
`
`Primary Examiner—James L. Dwyer
`Attorney, Agent, or Firm—Malcolm R. McKinnon
`[57]
`ABSTRACT
`A utility usage data and event data acquisition system
`effective to acquire inputserial data messages represent-
`ing the amount of consumed utility services and/or
`binary event data from one or several external sources
`having differing drive signal requirements, the system
`also being effective to reformat the input data and ap-
`pendan identification code and an error detection code
`to the acquired data, and thereafter transmit messages
`comprising the identification code, the acquired data,
`the error detection code and other control information
`to a central location through the agency of coaxial
`cables, public switched telephone networks or other
`transmission facilities utilizing data terminals which
`accept serial binary messages at logic level voltages.
`Data message transmission is initiated either at random
`times by an algorithm within the control program of a
`microprocessor incorporated in the system or from an
`externally applied commandsignal.
`
`38 Claims, 6 Drawing Figures
`
`[54]. UTILITY USAGE DATA AND EVENT DATA
`ACQUISITION SYSTEM
`Ronald S. Jahr, Naperville, IL;
`Thomas H. Cowell, Corunna, Mich.
`
`Inventors:
`
`[75]
`
`[73] Assignee:
`
`Systems and Support, Incorporated,
`Owosso, Mich.
`
`[21] Appl. No.: 679,627
`[22] Filed:
`Dec. 10, 1984
`
`[62]
`
`Related U.S. Application Data
`Division of Ser. No. 310,054, Oct. 9, 1981, Pat. No.
`4,504,831.
`
`Int. C14 a...esceeseseeeeees H04M 11/00; GO8C 19/00
`[51]
`[52] U.S, CL.
`....ssscscresecceeesereresneones 379/107; 340/870.03
`[58] Field of Search.............--000 340/870.02, 870.03,
`340/870.11, 870.19, 310 A; 364/483; 179/2 A, 2
`AM; 379/106, 107, 92
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3,114,900 12/1963 Anderson ......reseseseere 340/870.11
`
`8/1972 Rowse ......-
`.. 340/870.03
`3,688,271
`6/1974 Vercellotti etal. ............ 340/870.03
`3,820,073
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`Sheet 1 of4
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`U.S. Patent Nov. 17, 1987
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`U.S. Patent Nov. 17, 1987
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`U.S. Patent Nov. 17, 1987
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`

`1
`
`4,707,852
`
`UTILITY USAGE DATA AND EVENT DATA
`ACQUISITION SYSTEM
`
`This is a divisional of co-pending application Ser. No.
`06/310,054 filed on Oct. 9, 1981, now U.S. Pat. No.
`4,504,831.
`
`BRIEF SUMMARY OF THE INVENTION
`This invention relates to electronic data acquisition
`systems, and, more particularly, to an improved utility
`usage data and eventdata acquisition system for acquir-
`ing and transmitting utility usage and event data to a-
`central location. Systems embodying the present inven-
`tion accept either messages comprising a serial stream
`of binary digits representing the amount of consumed
`utility services or binary event data from external
`sources at each of several inputs to the system. Exam-
`ples of applications of systems embodying the present
`invention include, butare not limited to, the acquisition
`and transmission to a central location of usage data for
`various utilities such as water, gas and electricity, the
`acquisition and transmission of event data such as event
`data respecting the opening and closing of doors, the
`operation or disablement of valves or switches, the
`selection of broadcast programs for viewing orlisten-
`ing, and other data such as alarm data respecting fire,
`intrusion, and medical or other emergencies or condi-
`tions. Data acquisition systems embodying the present
`invention incorporate many features which provide a
`cost effective alternative to prior manual, semi-mech-
`anized and automatic methodsofutility usage data ac-
`quisition and processing, a primary application for sys-
`tems embodying the present invention being to auto-
`matically acquire utility usage data for one or more
`utility services at remote locations near the point of
`consumption and forward the data to a central location
`for processing while eliminating many ofthe costs asso-
`ciated with prior utility meter reading. In addition to
`reducing the costs associated with prior meter reading,
`data may be acquired more frequently with systems
`embodying the present invention so as to eliminate the
`need for estimated service billing which results when
`meters are not read at least once every billing cycle.
`Furthermore, data may be acquired at an even greater
`frequency to permit time-of-day usage monitoring and-
`/orbilling.
`A significant feature of systems embodying the pres-
`ent invention is the ability to accept serial binary data
`messages from electronic utility meter encoders pres-
`ently in use or available for use with many existing
`manual reading utility meters. Since the meter readings
`acquired from these encoders are cumulative and non-
`volatile, there is no requirement to store the utility
`usage data within the data acquisition means and thus °
`the data is immuneto loss resulting from powerinter-
`ruptions, device failure or transmission failures.
`Systems
`embodying the present
`invention are
`adapted to accommodate several different methods of
`data transmission to a central location. Transmission of
`the acquired data over a coaxial cable system may be
`accomplished by interfacing the data acquisition means
`to a radio frequency transmitter which is directly con-
`nected to the coaxial cable system. A receiver at the
`central location demodulates the radio frequencysig-
`nals and recovers the data message. Alternatively, the
`data acquisition means and an associated data processor
`at a central location may comprise a sub-system of an
`
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`information distribution system. These systems provide
`a wide range of advanced telecommunication and sub-
`scriber services which may include alarm reporting,
`energy management, meterreading, pay television ser-
`vices, remote banking and shopping services, and usage
`sensitive billing among others. In this application, the
`data acquisition means interfaces directly with a sub-
`scriber terminal which communicates with and may be
`controlled by a host processor at a remote location.
`Data acquired by the data acquisition meansis transmit-
`ted to the subscriber terminal and thence to the host
`processor over transmission facilities utilized by the
`information distribution system. Transmission facilities
`utilized by an information distribution system mayin-
`clude coaxial cable, fiber optic cable, a switched or
`private line telephone network or any combination of
`these or other transmission media. The acquired data is
`transmitted to the central locationasit is received at the
`host processor or the acquired data is stored at the host
`processor and transmitted to the central location upon
`request from the central location.
`Systems embodying the present invention utilize a
`single-chip microprocessor whichsignificantly reduces
`the number of discrete analog and digital electronic
`components which would be required to accomplish
`the data acquisition task, thus reducing the cost of the
`system itself and improving reliability. Data message
`transmission through the system to the central location
`is initiated at random times determined independently
`by each acquisition means or by the application of an
`external logic level commandsignal to the acquisition
`means. The present invention further reduces the cost
`of data collection since bi-directional communication
`with either the central location or other acquisition
`means sharing the same communication channelis not
`required.
`In systems embodying the present invention, an error
`detection code is appended to each data messagetrans-
`mitted by the system to assure, with high reliability, that
`the data messagereceived at the central location is free
`of errors introduced during transmission. Moreover, the
`number of inputs to systems embodying the present
`invention may be easily expanded with the addition of
`applique circuitry described hereinafter in greater detail
`and permitting the system to accommodate a large num-
`ber of data sources as might be encountered in apart-
`ment and commercial complexes. Additional applique
`circuitry provides a means of detecting an impending
`powerinterruption or tamper alarm and transmitting a
`message with this data to the central location. The data
`messages transmitted by systems embodying the present
`invention may be readily adapted for a packet data
`transmission protocol thusfacilitating the application of
`the invention to current and future data distribution
`systems.
`.
`An object of the present invention is to overcome
`disadvantages in prior manual, semi-mechanized and
`automatic methods and apparatus for data acquisition
`and processing of the indicated character and to pro-
`vide an improved utility usage data and event data ac-
`quisition system incorporating improved means for
`acquiringutility service usage data at a central location
`from remote locations whichutilize serial binary meter
`encoding devices.
`Another object of the present invention is to provide
`an improved utility usage data and event data acquisi-
`tion system capable of utilizing several data transmis-
`sion media.
`
`6
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`

`

`3
`Another object of the present invention is to provide
`an improved utility usage data and event data acquisi-
`tion system capable of accepting serial binary data from
`various meter encoding devices or binary event data at
`any of several inputs to the system.
`Another object of the invention is to provide an im-
`proved utility usage data and event data acquisition
`system incorporating improved meansprovidingfor the
`immediate transmission of a data message to a central
`location upon the occurrenceofa binary eventat any of
`several inputs to the system or upon the application of
`primary powerto the system.
`Another object of the invention is to provide an im-
`proved utility usage data and event data acquisition
`system which mayinclude optional meansfor transmit-
`ting data messagesto a central location at random times
`determined independently by each remote data acquisi-
`tion means thus permitting a number of acquisition
`means to share a common communication channel with-
`out such acquisition means communicating with each
`other or receiving commandsfrom the central location.
`Still another object of the present invention is to
`provide an improvedutility usage data and event data
`acquisition system which, when applied to a switched
`telephone network, incorporates means for establishing
`a telephone connection between the remote data acqui-
`sition means and the central location at random times
`determined independently by each acquisition means
`when it is unlikely that the telephonefacility will be
`required for normal service.
`Yet another object of the present invention is to pro-
`vide an improved utility usage data and event data ac-
`quisition system that is economical to manufacture and
`assemble, durable, efficient and reliable in operation.
`The aboveas well as other objects and advantages of
`the present invention will become apparent from the
`following description,
`the appended claims and the
`accompanying drawings.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG.1 is a schematic block diagram ofa utility usage
`data and event data acquisition system embodying the
`present invention and depicting several modes by which
`the data acquisition means may communicate with a
`central location;
`FIG.2 is a schematic diagram of the data acquisition
`means embodied in the system illustrated in FIG.1;
`FIG.3 is a schematic diagram of an optional applique
`circuit which may be incorporated within the data col-
`lection means to provide advance warning of an im-
`pending power interruption to the data collection
`means or an indication that such means has been tam-
`pered with;
`FIG.4 is a schematic diagram of an applique timing
`circuit which may be incorporated in the data acquisi-
`tion means when a radio frequency transmitter is uti-
`lized to transmit a composite data message to a central
`location;
`:
`FIG. 5 is a schematic diagram illustrating means for
`expanding the numberofinputs to the system; and
`FIG. 6 is a schematic diagram illustrating means
`which permits operation of the system with the public
`switched telephone network.
`DETAILED DESCRIPTION
`
`Referring to the drawings, a utility usage data and
`event data acquisition system, generally designated 10,
`embodying the present inventionis illustrated therein.
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`Asshownin FIG.1, the system 10 includes data acquisi-
`tion units, generally designated 11A and 11A-1, which
`are identical and shownin greater detail in FIG. 2. The
`number 11B designates an alternate embodiment of a
`data acquisition unit which is shownin greater detail in
`FIG. 6. The system illustrated in FIG. 1 depicts three
`different modes by which the data acquisition units
`11A, 11A-1 or 11B may communicate with a central
`location generally designated 20 and transmit a compos-
`ite serial binary data message which includes data ac-
`quired from four inputs, which inputs are designated
`12A, 12B, 12C and 12D inall three modes.
`Referring to the first modeillustrated, the data acqui-
`sition unit ILA transmits a composite serial binary data
`message (which includes data acquired from inputs
`12A, 12B, 12C and 12D)to a radio frequency transmit-
`ter 15 at logic level voltages over the lead 13B. The
`transmitter 15 establishes and modulates a radio fre-
`quencycarrier signal which carries the composite serial
`binary data message. The outputof the radio frequency
`transmitter 15 is connected to a coaxial cable distribu-
`tion system 16A by a coaxial cable 16B. At the central
`location 20, a radio frequency receiver 22 is connected
`to the coaxial cable distribution system 16A by a coaxial
`cable 16C.
`The radio frequency receiver 22, which is tuned to
`the sameradio carrier signal frequency produced by the
`transmitter 15, amplifies, detects and demodulates the
`radio signal and transmits the recovered composite
`serial binary data message to the central data processor
`21 at logic level voltages over the lead 23. The compos-
`ite serial binary data messages generated by the data
`acquisition unit 11A is transmitted at random times.
`Therefore,
`in this configuration, a plurality of radio
`frequency transmitters 15 and their associated data ac-
`quisition devices 11A may share a common radio fre-
`quency channel with a low probability that two or more
`transmitters will be activated simultaneously preventing
`accurate reception of the data messages by the receiver
`22.
`Referring now to the second communication mode
`shown in FIG.1, the data acquisition unit 11B commu-
`nicates with the central location 20 over a switched
`telephone network 28A. The data acquisition unit 11B
`controls a telephone network modem 29 capable of
`establishing a telephone connection to a similar modem
`26 at the central location 20. The data acquisition unit
`11B initiates calls to the central location 20 at random
`times, as for example, between the hours of midnight
`and 5:00 a.m., when it is unlikely that the dedicated
`telephone loop 28B and 28Cwill be required to provide
`normal telephone service. Following establishment of
`the telephone connection to the central location 20, the
`data acquisition unit 11B transmits the serial binary data
`message which includes data acquired from the inputs
`42A, 12B, 12C and 12D to the telephone network
`modem 29 at logic level voltages over the lead 31. The
`telephone network modem 29 transmits the composite
`serial binary data message by shifting an audio fre-
`quencycarrier between two frequencies corresponding
`to binary zero and binary one. The audio frequencies
`are transmitted to the switched telephone network 28A
`over the subscriber telephone loop 28B and 28C. The
`telephone network modem 26at the central location 20
`receives the modulated audio frequency carrier signal
`over a dedicated telephone loop 28D and 28E. The
`telephone network modem 26 demodulates the compos-
`ite serial binary data message from the modulated audio
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`5
`frequencycarrier signal and transmits the data message
`to the central data processor 21 at logic level voltages
`overthe lead 27 asit is received.
`Referring to the third communication mode shownin
`FIG.1, the data acquisition unit 11A-1, whichis similar
`to the data acquisition unit 11A, communicates over the
`leads 13C and 17 with a subscriber terminal 18D which
`is part of an information distribution system 18A com-
`prised of a host processor 18B, transmission facilities
`18C and the subscriber terminal 18D. The data acquisi-
`tion unit 11A-1 transmits the composite serial binary
`data message which includes data acquired from the
`inputs 12A, 12B, 12C and 12D atlogic level voltages to
`the subscriber terminal 18D at random times or option-
`ally transmits the message upon receipt of a command
`from the subscriber terminal 18D. The optional com-
`mandis a logic level voltage change applied to the lead
`17 by the subscriber terminal 18D. The composite serial
`binary data messageis transmitted to the host processor
`18B overthe transmissionfacility 18C. The host proces-
`sor 18B then transmits the data message either immedi-
`ately or upon request from the central data processor 21
`over a data link 19 to the data link interface 24 at the
`central location 20. The data link interface 24 transmits
`the received composite serial binary data message to the
`central data processor21atlogic level voltages overthe
`lead 25.
`Although three modes of communication between
`the data acquisition units 11A, 11A-1 or 11B and the
`central location 20 are depicted in FIG. 1, any other
`mode which incorporatesfacilities capable of transmit-
`ting a serial binary data message from the data acquisi-
`tion units to the central location 20 may beutilized.
`FIG.2 is a schematic diagram ofthe data acquisition
`units IIA and IIA-1 which are comprised of a microcon-
`troller 35 that executes a control program contained
`within the read-only program memory which is an
`integral part of the microcontroller 35. The microcon-
`troller 35 acquires either serial binary data messages
`from oneto fourutility meter encoders connected to the
`input leads, such as the input leads 12A, 12B, 12C and
`12D,respectively, or binary event data from one to four
`external sources connected to the respective input leads
`12A, 12B, 12C and 12D. A composite serial data mes-
`sage including the data acquiredat the input leads 12A,
`12B, 12C and 12Dis transmitted at logic level voltages
`over the output lead 13A at random times determined
`byan algorithm within the microcohtroller 35 program,
`upon the application of power to the unit on the leads
`43A or 43B, upon the application of an external logic
`level commandsignalto the lead 17, or upon the detec-
`tion of a binary event represented by transition of logic
`level state at any of the input leads 12A, 12B, 12C or
`12D. The output lead 13A may be interfaced with a
`radio frequency transmitter at the lead 13B or a sub-
`scriber terminal unit at the lead 13C for transmission of
`the composite serial data message to the central location
`20 illustrated in FIG.1.
`.
`The composite serial data messages transmitted over
`the leads 13A, 13B and 13C and thus to the central
`location 20 include the data acquisition unit identifica-
`tion code, binary event data, data messagesfrom utility
`meter encoders and an error detection code. The data
`acquisition unit identification code is a twelve bit code
`which permits the central location 20 to uniquely iden-
`. tify composite serial data messages from up to four
`thousand ninety five data acquisition units sharing a
`common communication channel,
`i.e., a single radio
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`frequency channel. The identification code for each
`data acquisition unit is implemented by opening the
`appropriate normally closed connections 36A through
`36L. The binary coded identification ranges in decimal
`value from zero with all
`twelve connections 36A
`through 36L closed to four thousandninetyfive with all
`twelve connections 36A through 36L open. Theleast
`significant bit is 36A and the mostsignificantbit is 36L.
`With reference to the input leads 12A, 12B, 12C and
`12D, the microcontroller 35 acquiresserial binary data
`from oneto fourutility meter encoders connected to the
`input leads. Each meter encoder requires three connec-
`tions to the data acquisition unit: a ground connection to
`the lead 37, encoder data output connected to oneof the
`four input leads 12A, 12B, 12C or 12D,and an encoder
`drive signal obtained from leads 38 or 39. Only one
`meter encoderdata output may be connected to any one
`of the input leads. Two types of meter encoder drive
`signals are provided. Thelead 38is utilized with meter
`encoders which require a constant drive voltage of
`eight to fifteen volts, and the lead 39 is utilized with
`meter encoders which require a clockedfive volt drive.
`The Zener diode ZDI regulates the eight to fifteen volt
`- drive to five volts through the dropping resistor R11.
`The eight to fifteen volt drive voltage is supplied
`through an optical-isolator OPT1. The conduction of
`the optical-isolator OPT1is controlled througha resis-
`tor R12 by the microcontroller on the lead 40.
`Meter encoders which require a constant drive volt-
`age transmit a serial binary data message whichincludes
`the utility usage data upon application of the constant
`drive voltage. Meter encoders which require a clocked
`drive transmit a serial binary data message which in-
`cludetheutility usage data only while the drive voltage
`is clocked or switched between high and low logic
`levels. Utilizing this difference in the operation of the
`two types of meter encoders, the acquisition units 11A
`or 11A-1 accepteither type of meter encoder connected
`to any- one of the four inputs 12A, 12B, 12C or 12D
`without regard to the type of encoder so connected.
`The acquisition and transmission ofutility meter serial
`encoderdata followingtheinitiation of composite data
`message transmission is accomplished by the microcon-
`troller 35 repeating the following procedure for each of
`the four inputs 12A, 12B, 12C and 12D in sequence
`beginning with the input 12A: the microcontroller 35
`applies a constant high logic level voltageto the lead 40.
`The constant high logic level voltage is applied to the
`light emitting diode within the optical-isolator OPT1
`throughthe resistor R12 and the phototransistor within
`the optical-isolator OPT1is forced into saturation and
`thus switches the eight to fifteen volt supply voltage at
`the collector of the phototransistor to the encoderdrive
`lead 38. The Zener diode ZD1 and the dropping resistor
`R11 reduce the constant eight to fifteen volt drive volt-
`age to a constantfive voltsat the lead 39. Meter encod-
`ers connected to the lead 38 or 39 which operate with a
`constant drive voltage will commence transmission of
`their serial binary data messages. These messages ap-
`pear simultaneously on the input leads 12A, 12B, 12C or
`12D which connect to the outputs of the meter encod-
`ers of the constant drive voltage type. Meter encoders
`of the type which require a clocked drive voltage will
`not respondat this time on their respective input leads
`since the drive voltage is held constant. The microcon-
`troller 35 examines the input lead 12A for a change of
`logic state which indicates the start of the serial data
`message from a constant drive voltage encoder.If logic
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`level transitions are detected by the microcontroller 35,
`the seria] data message from the encoderis accepted by
`the microcontroller 35 as received over the input lead
`12A and the messageis appended to the composite data
`message currently in the process of transmission over
`the lead 13A.If logic level transitions are not detected
`at the input lead 12A,indicating that no serial encoder
`of the constant drive voltage type is connected to this
`input
`lead,
`the microcontroller 35 will commence
`clocking the encoder drive voltage at the leads 38 and
`39 by clocking the logic level voltage at the lead 40. A
`serial encoder of the type which requires a clocked
`drive voltage connected to the input lead 12A will
`commencethe transmission of the serial data message.
`The microcontroller 35 detects the serial data message
`at the input lead 12A as logic level transitions. The
`serial data message from the encoderis accepted by the
`microcontroller 35 over the input lead 12A and ap-
`pended to the composite data message. If neither type of
`serial encoder is detected at input lead 12A, the mi-
`crocontroller 35 removes the drive voltage from the
`leads 38 and 39 by dropping the logic voltage on the
`lead 40 to a low level and appends null data to the
`composite data message. The null data indicates to the
`central location 20illustrated in FIG.1 that neither type
`of serial encoder is connected to input lead 12A. The
`foregoing process is repeated for each of the remaining
`input leads 12B, 12C and 12D in sequence, thus acquir-
`ing and appending to the composite data message utility
`usage data from serial encoders connected to the inputs.
`Thus a system with differing serial encoders communi-
`cates with different drive signal formats to the data
`collection unit.
`In addition to acquiring data from utility meterserial
`data encoders, the data acquisition units 11A or 11A-1
`detect and transmit binary event data which occursat
`any of the input leads 12A, 12B, 12C or 12D.A binary
`event is any transition of logic level state, either low to
`high level or high to low level which occurs at any of
`the input leads. Sources of binary event data mayin-
`clude, but are not limited to, normaliy open or normally
`closed switches or push buttons, relay contacts, or any
`external circuitry capable of producing a logic state
`transition at any of the input leads. Each of the four
`input leads function independently and each may be
`connectedto either a utility meter serial data encoder or
`a source of binary event data but not both. Each time a
`binary eventis detected at any of the input leads, trans-
`mission of the entire composite serial data message over
`the leads 13A, 13B and 13Cis initiated. Composite data
`messages initiated by binary events are retransmitted
`twice or more at closely spaced random timesto in-
`crease the probability that the composite data message
`including the binary event data is received without
`error at the central location 20.
`A crystal resonant circuit CRC-1 is provided for the
`microcontroller 35, the crystal resonant circuit being
`comprised of a crystal CR-1, resistors R5 and R6, and a
`capacitor C5 which are electrically connected asillus-
`trated in FIGS.2 and 6.
`Referring to FIG. 4, an applique timing circuit is
`illustrated which is included with the data acquisition
`unit 11A when the radio frequency transmitter 15 is
`utilized to transmit the composite data message to the
`central location 20. The function of this applique timing
`circuit is to provide powerto the transmitter over the
`jead 14A for the duration of composite data message
`transmission after which power to the transmitter on
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`the lead 14A is removed thus disabling the radio fre-
`quency transmitter 15. Power is applied to the leads
`14A and 14B bythe applique timing circuit when a high
`to low level logic state transition occurs on the lead
`13B. This transition occurs at the beginning of the com-
`posite data message transmission over the leads 13A,
`13B and 13C. This high to low logic level transition on
`the lead 13B triggers an integrated timing circuit 51
`which brings the leads 14A and 14B from a low logic
`level to a high logic level for a fixed time determined by
`the time constant of the resistor R4 and the capacitor
`C4. The time constant-is chosen to produce a high logic
`level output at the lead 14A for a duration slightly
`longer than the time required to transmit the composite
`data message. Thus the applique timing circuit of FIG.
`4 controls powerto the radio frequency transmitter and
`thus controls the maximum duration of the transmitted
`radio frequency carrier over the coaxial cable 16B. This
`circuit provides a degree of protection against the possi-
`bility of malfunctions which might result in a “locked
`on” or constant radio frequency carrier which would
`interfere with the transmissions of other data acquisition
`units which share a common radio frequency channel.
`The lead 14B is an input to the microcontroller 35
`which permits the microcontroller to monitor the status
`of the power applied to the transmitter 15. Should a
`malfunction occur which results in the constant applica-
`tion of power over the lead 14A to the transmitter 15
`and thus the transmission of a constant radio frequency
`carrier, the microcontroller detects this condition over
`the lead 14B and will commence the continuoustrans-
`mission of the composite data message over the lead
`13B and thus to the central location 20, permitting iden-
`tification at the central location 20 of the malfunction-
`ing data acquisition unit.
`Powerfor the microcontroller 35 is obtained over the
`lead 41 from a three-terminal integrated circuit voltage
`regulator 42 which is connected to capacitors C2, C3
`and groundas illustrated in FIGS. 2 and 6. The voltage
`regulator 42 reduces and regulates the primary eight to
`fifteen volt supply voltage appearing at the lead 43C to
`five volts required by the microcontroller 35. The pri-
`mary eight to fifteen volt supply voltage may be pro-
`vided from an external DC powersupply connected to
`the leads 43A and 44A or from the subscriber terminal
`18D over the leads 43B and 44B. A wiring option 45A
`and 45Bselects thie source of the primaryeightto fifteen
`volt supply voltage. The resistor R1, diode D1 and
`capacitor Ci with the wiring option 46A installed pro-
`vide a low level reset signal on the lead 47 to the mi-
`crocontroller 35 each time the primary supply voltage is -
`restored to the lead 43C. The microprocessor 35 trans-
`mits a composite data message to the central location
`following the occurrence of eachresetsignal at the load
`47. Information within the composite data message
`indicates to the central location 20 that the data message
`transmission wasinitiated by a reset signal. The appli-
`que circuit depicted schematically in FIG. 3 may be
`incorporated within the system to generate a reset sig-
`nal and thusinitiate the transmission of a composite data
`message to the central location 20 upon the detection of
`an impending interruption of the primary supply voli-
`age or that tampering with a data acquisition unit 11A
`or 11A-1 has occurred. In the embodiments of the in-
`vention incorporating this feature, the wiring option
`46B is installed and the option 46A remains open. An
`integrated circuit voltage level detector 49 produces a
`low logic level voltage at the lead 48 when the primary
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`inputs and/or binary event data in the mannerprevi-
`supply voltage on the lead 43A falls below the thresh-
`ously recited.
`old voltage on the lead 50 established by the voltage
`FIG. 6 is a schematic diagram of the alternate em-
`divider resistors R2 and R3, the resistor R2 also being
`bodiment of the invention illustrated in FIG. 1 and
`connected in series with a resistor R7 as illustrated in
`referenced by the numeral 11B. In this embodiment of
`FIG.3. Thetransition from a high to a lowlogic level
`the invention, a microcontroller 58 acquires utility
`on the lead 48 permits the capacitor C1 to b