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WO1994017367A1 - Dispositif de mesure universel - Google Patents

Dispositif de mesure universel Download PDF

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Publication number
WO1994017367A1
WO1994017367A1 PCT/US1994/000855 US9400855W WO9417367A1 WO 1994017367 A1 WO1994017367 A1 WO 1994017367A1 US 9400855 W US9400855 W US 9400855W WO 9417367 A1 WO9417367 A1 WO 9417367A1
Authority
WO
WIPO (PCT)
Prior art keywords
input
selecting
conditioning
measurement device
providing
Prior art date
Application number
PCT/US1994/000855
Other languages
English (en)
Inventor
Martin J. Burns
Original Assignee
Honeywell Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Honeywell Inc. filed Critical Honeywell Inc.
Priority to AU60949/94A priority Critical patent/AU6094994A/en
Publication of WO1994017367A1 publication Critical patent/WO1994017367A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/08—Circuits for altering the measuring range
    • G01R15/09—Autoranging circuits
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D21/00—Measuring or testing not otherwise provided for
    • G01D21/02—Measuring two or more variables by means not covered by a single other subclass

Definitions

  • This invention is in the field of signal conditioning devices. More specifically, this invention is in the field of signal conditioning devices which must be capable of conditioning signals from varying sensor inputs and converting those signals to usable outputs.
  • HVAC heating, ventilation and air conditioning system
  • a system must be capable of measuring many different conditions.
  • An example would be the system must be capable of measuring the discharged air temperature from a furnace, damper positions, room temperature, outside air temperature, and numerous other conditions.
  • each of these measurements would be done by utilizing a single sensor and the proper conversion circuitry to provide a signal to a microprocessor so that the microprocessor can evaluate this information.
  • RTD resistance temperature devices
  • a shortcoming is that the variation of resistance is small with respect to temperature and this requires special circuitry to amplify and linearize the resistance produced. Thus, when one utilizes an RTD, one must utilize secondary circuitry to scale the inputs. As each RTD requires conditioning circuitry, it is desirable that the same circuitry be utilized for all RTDs. However, since RTDs are not the only sensor inputs, the system must be capable of conditioning many variable inputs.
  • the universal measurement device utilizes highly precise .1% tolerance resistors with common ground at the circuitry for the input.
  • a switchable 5-volt DC source was provided to power sensors briefly to allow measurement.
  • several amplifiers can be utilized to adjust the range of input voltages generated by currents flowing through the precision resistor.
  • the inputs to the universal measurement device are converted to a voltage by providing the input to a precision resistor electrically connected to ground. The voltage drop across the resistor provides voltage input to the buffer amplifier.
  • a desired input is conditioned selectin the desired input and routing the input to a buffer amplifier via an analog selector.
  • the buffered signal is provided to all of the conditioning amplifiers.
  • the desired buffer and scaling amplifier is chosen based on the sensor type.
  • the voltage at this point is sampled and combined with a reference leg made of two precision resistors. Since the RTD, 200 ohm resistor and a buffer amp are chosen with negligible error, the bridge circuit can accurately scale the voltage range of interest.
  • the selected amplified and scaled output is routed to the analog-to-digital converter. To calibrate the system, measurements are taken using reference resistors and a regression is performed and the results stored in EEPROM on the universal measurement device mother board. Thus, errors due to component initial values can be compensated for and used for each measurement.
  • Fig. 1 illustrates the schematic for the universal measurement device.
  • Fig. 2 illustrates one embodiment of an input circuit.
  • Fig. 3 illustrates a switchable 5 -volt supply.
  • the preferred embodiment comprises at least one input circuit 10, at least a first multiplexer 30, buffer 40, amplifying circuit 50, a first scaling circuit 51 and a second scaling circuit 52.
  • the universal measurement device also comprises a second multiplexer 60 and an A-to-D converter 70.
  • the input circuit 10 comprises an input node 15A which is electrically connected to a sensor (not shown). Node 15A is electrically connected to resistor 11 A which is also connected to ground. In this manner, when a sensor provides an input signal to node 15 A, resistor 11 A converts that input signal to a voltage.
  • the preferred embodiment is designed to operate with an input range of 0-20 milliamps. For this reason, a 200 ohm resistor has been selected for a resistor 11 A.
  • the scaled inputs at resistor 11 A will be between 0 volts to 4 volts.
  • the voltage drop across resistor 11 A is provided to multiplexer 30 through resistor 12 A.
  • Resistor 12A must be a resistor of a sufficient value to prevent a significant current drained through resistor 12.
  • multiple input circuits 10A through ION are illustrated. As this system is only limited by the number of multiplexer 30 inputs, there is no limit on the number of sensor inputs which can be conditioned through this circuit.
  • An outside source such as a microprocessor, provides a first input 80 to multiplexer 30 to determine which one of the inputs the outside source wishes to investigate.
  • a 74HC4051 multiplexer is utilized and is available from National Semiconductor.
  • the selected input signal is provided to buffer 40 and the output of buffer 40 is provided to multiple calibration amplifiers.
  • the buffered signal is provided to multiplier 50 and conversion amplifiers 51 and 52.
  • a second input 82 from the outside source determines which one of the conditioned signals is provided to the A-to-D converter 70.
  • A-to-D converter 70 when receiving this signal, converts it to a digital signal which is provided to a microprocessor or other source which requires the sensed signal.
  • Fig. 2 illustrates a second embodiment of input circuit 10.
  • Fig. 2 still utilizes resistor 11; however, a transient suppression diode 17 is electrically connected to node 15 and ground. In this manner, transients, which may be harmful to the system, are suppressed. Due to the simplistic input circuit utilized and the use of a high impedance input to the buffer, it is possible to avoid transient problems with a minimal parts count. This helps in achieving the overall goal of the invention of great versatility with a minimum parts count.
  • Sensor 16 provides an input current to input node 15. For this embodiment, an RTD sensor is used.
  • An RTD sensor may be a Honeywell C7100A averaging discharge sensor, or a Honeywell C7170A encapsulated temperature sensor, or the system may utilize a thermistor.
  • the only requirement for a sensor is that it provide a 0 to 20 milliamp input.
  • a 5 -volt source is provided at the input to the RTD sensor 16.
  • a switched 5-volt source is provided to the sensors to allow a microprocessor or some other source to turn sensor 16 ON and OFF, thus, preventing continuous operation which would cause self-heating errors.
  • a switchable 5-volt source as illustrated in Fig. 3, is provided.
  • the switchable 5-volt source comprises a transistor 92 with the source electrically connected to a 5.3 volt DC source.
  • the 5.3 volt DC source is also electrically connected to resistor 93 which is electrically connected to the base of transistor 92.
  • the emitter of transistor 92 is electrically connected through diode 91 to output node 90.
  • Output node 90 provides a 5-volt source to all of the external sensors.
  • Transient protection is provided by diode 91 and zenor diode 96.
  • the base of transistor 92 is also electrically connected to resistor 94 which is electrically connected to an external source.
  • External source 95 may be a signal provided by a microprocessor or it may be some other form of an external switch. When external source signal 95 is electrically connected to ground, transistor 92 is energized and node 90 provides a 5-volt source. When external source signal 95 is electrically high or a high impedance, transistor 92 is de-energized and node 90 does not provide any voltage and thereby shuts down all external sensors. In this manner, self-heating is prevented.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Arrangements For Transmission Of Measured Signals (AREA)

Abstract

L'invention concerne un dispositif de mesure universel conçu pour recevoir des signaux d'entrée provenant d'au moins une source extérieure, ledit dispositif étant pourvu au moins d'un moyen de réception de signal d'entrée destiné à la réception d'un signal d'entrée provenant d'un capteur extérieur. Le moyen d'entrée fournit un signal de sortie équivalent au signal d'entrée provenant du capteur extérieur à un moyen de sélection qui sélectionne un des moyens de réception de signal d'entrée et fournit le signal de sortie provenant du moyen de réception de signal d'entrée à un amplificateur séparateur. L'amplificateur séparateur est relié électriquement à au moins un moyen de conversion. Chacun des moyens de conversion reçoit ensuite le signal de sortie sélectionné provenant du moyen de réception de signaux d'entrée et convertit ce signal. Chacun des moyens de conversion fournit son signal de sortie à un second moyen de sélection. Un second moyen de sélection sélectionne le signal approprié provenant du moyen de conversion, ce signal constituant ensuite le signal d'entrée de capteur approprié, converti, destiné à l'utilisation.
PCT/US1994/000855 1993-01-22 1994-01-21 Dispositif de mesure universel WO1994017367A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU60949/94A AU6094994A (en) 1993-01-22 1994-01-21 Universal measurement device

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US745593A 1993-01-22 1993-01-22
US08/007,455 1993-01-22

Publications (1)

Publication Number Publication Date
WO1994017367A1 true WO1994017367A1 (fr) 1994-08-04

Family

ID=21726260

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1994/000855 WO1994017367A1 (fr) 1993-01-22 1994-01-21 Dispositif de mesure universel

Country Status (2)

Country Link
AU (1) AU6094994A (fr)
WO (1) WO1994017367A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2136568A1 (es) * 1997-12-02 1999-11-16 Doiki S Coop Aparato electronico para medicion y control dimensional de piezas mecanizadas.
ES2140992A1 (es) * 1996-03-28 2000-03-01 Consejo Superior Investigacion Medidor multicota para piezas producidas por maquinas-herramienta.
CN104049658A (zh) * 2013-03-14 2014-09-17 深圳市海洋王照明工程有限公司 精密电压放大电路

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3449685A (en) * 1967-04-25 1969-06-10 Us Navy Automatic range selector employing plural amplifiers of different gains
EP0254142A2 (fr) * 1986-07-24 1988-01-27 NICOTRA SISTEMI S.p.A. Transducteur simple/multiple de mesure d'une ou de plusieurs quantités physiques ou variables électriques

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3449685A (en) * 1967-04-25 1969-06-10 Us Navy Automatic range selector employing plural amplifiers of different gains
EP0254142A2 (fr) * 1986-07-24 1988-01-27 NICOTRA SISTEMI S.p.A. Transducteur simple/multiple de mesure d'une ou de plusieurs quantités physiques ou variables électriques

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
CH. BURNIAUX: "Amplificateurs Programmables: conception et applications", TOUTE L'ELECTRONIQUE, no. 415, November 1976 (1976-11-01), pages 49 - 53 *
J. BORGMAN: "Automatic range switch", ELEKTOR, vol. 6, no. 7/8, July 1980 (1980-07-01), CANTERBURY, pages 7.99 - 8.00 *
V. TALKENBERGER: "Automatische Messbereichsumschaltung beim C 520 D", RADIO FERNSEHEN ELEKTRONIK, vol. 32, no. 5, May 1983 (1983-05-01), OST-BERLIN,DDR, pages 298 - 299 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2140992A1 (es) * 1996-03-28 2000-03-01 Consejo Superior Investigacion Medidor multicota para piezas producidas por maquinas-herramienta.
ES2136568A1 (es) * 1997-12-02 1999-11-16 Doiki S Coop Aparato electronico para medicion y control dimensional de piezas mecanizadas.
CN104049658A (zh) * 2013-03-14 2014-09-17 深圳市海洋王照明工程有限公司 精密电压放大电路

Also Published As

Publication number Publication date
AU6094994A (en) 1994-08-15

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