Sensor system for determining a physical, measured variable

• US 8,197,135 B2
• Filed: 11/24/2006
• Issued: 06/12/2012
• Est. Priority Date: 12/23/2005
• Status: Active Grant

• Current Assignee: Endress + Hauser GmbH + Company KG (Endress+Hauser AG)
• Original Assignee: Endress + Hauser GmbH + Company KG (Endress+Hauser AG)
• Inventors: Grozinger, Roland, Ruf, Klaus
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): Jagan, Mirellys
• Application Number:
  US12/086,781
• Publication Number:
  US 20090201972A1
• Time in Patent Office: 2,027 Days
• Field of Search: 374/183, 374/185, 374/178, 374/117
• US Class Current: 374/183
• CPC Class Codes: G01F 23/2962 Measuring transit time of reflected waves
• CPC Class Codes: G08C 19/02 in which the signal transmitted is magnitude of current or voltage G08C19/36, G08C19/38 take precedence

Abstract

A sensor system for determining a physical, measured variable, and includes a sensor and a control/evaluation unit, which are spatially separated from one another and electrically conductively connected via a cable having at least two conductors, wherein provided in the sensor are a temperature measuring element for determining temperature and a sensor identifier for sensor identification. The control/evaluation unit drives the temperature measuring element and the sensor identifier via a shared conductor with a positive voltage or a negative voltage, and, depending on the applied voltage, reads a temperature measured value of the temperature element or an identifying value of the sensor identifier.

Claims

1. A sensor system for determining a physical, measured variable, comprising:

a sensor; and

a control/evaluation unit, which are spatially separated from the sensor and electrically conductively connected with the sensor via a cable having at least two conductors, wherein;

provided in said sensor are a temperature measuring element for determining temperature and a sensor identifier for sensor identification;

said control/evaluation unit drives said temperature measuring element and said sensor identifier with a positive voltage or a negative voltage via a shared conductor of said at least two conductors and, depending on the applied voltage, reads a temperature measured value of said temperature element or an identifying value of said sensor identifier;

a temperature-dependent resistance is provided in said temperature measuring element; and

an identifying resistance is provided in said sensor identifier; and

in series with said temperature-dependent resistance and/or in series with said identifying resistance, in each case, an electrical blocking element of opposed blocking direction is provided.

2. The sensor system as claimed in claim 1, wherein:

said sensor is an ultrasonic sensor for ascertaining a fill level in a container, and a piezoelectric transducer is provided in said ultrasonic sensor as sensor element for ascertaining the physical variable.

3. Apparatus as claimed in claim 1, further comprising:

a third conductor in the cable which serves for operating said sensor element by said control/evaluation unit.

4. The sensor system as claimed in claim 1, further comprising:

a switching element in said control/evaluation unit for switching the positive voltage or the negative voltage and corresponding series resistances onto said shared conductor.

5. The sensor system as claimed in claim 4, wherein:

the particularly applied positive voltage or negative voltage with the corresponding series resistance and said sensor identifier or said temperature measuring element form, via said two conductors of the cable, a voltage divider.

6. The sensor system as claimed in claim 1, further comprising:

at least one electrical, blocking element in said temperature measuring element and/or in said sensor identifier.

7. The sensor system as claimed in claim 6, wherein:

the blocking element comprises a diode.

8. The sensor system as claimed in claim 6, wherein:

said blocking element comprises a field-effect transistor, or a unipolar transistor.

9. The sensor system as claimed in claim 8, wherein:

said field-effect transistor is so arranged with respect to the temperature-dependent resistance of said temperature measuring element or with respect to the identifying resistance of said sensor identifier that a voltage drop at the temperature-dependent resistance or at the identifying resistance switches on said field-effect transistor.