Method and Apparatus for Determining a Process Variable

• US 20140172349A1
• Filed: 12/12/2013
• Published: 06/19/2014
• Est. Priority Date: 12/18/2012
• Status: Abandoned Application

• Current Assignee: ndress+Hauser Wetzer GmbH+Co., KG
• Original Assignee: ndress+Hauser Wetzer GmbH+Co., KG
• Inventors: Hrle, Thomas
• Application Number:
  US14/104,206
• Publication Number:
  US 20140172349A1
• Time in Patent Office: Days
• US Class Current: 702/130
• CPC Class Codes: G01K 15/005 Calibration

Abstract

A method and apparatus for determining a process variable, of a primary sensor, wherein by means of the primary sensor an analog measurement signal is produced, which analog measurement signal is converted into a digital signal representing the measured variable, wherein by means of at least one secondary sensor at least one reference signal is produced, and wherein as a function of the point in time, at which the reaching of a predetermined state of the process variable, especially the reaching of a value of the reference signal.

Claims

1-15. -15. (canceled)

16. A method for determining a process variable, especially for validation, adjusting, calibrating and/or certification of a primary sensor comprising the steps of:

producing, by means of the primary sensor an analog measurement signal representing a process variable;

converting the analog measurement signal by means of an analog to digital converter into a digital signal representing the measured variable;

producing by means of at least one secondary sensor, at least one reference signal, representing the process variable, preferably a state of the process variable, such as, for example, a defined standard state; and

displaying the reference as a function of the point in time, at which the reaching of a predetermined state of the process variable, especially the reaching of a value of the reference signal itself, occurs wherein;

the value of the measurement signal of the primary sensor converted by means of the analog to digital converter is logged; and

/or

the connection between the analog to digital converter and the primary sensor is interrupted; and

/or

the sampling rate of the value of the measurement signal of the primary sensor converted by means of the analog to digital converter is changed; and

/or

a processing, especially a measured value averaging, of the value of the measurement signal of the primary sensor converted by means of the analog to digital converter is changed in the evaluation unit.

17. The method as claimed in claim 16, wherein:

the measurement signal of the primary sensor is a continuous measurement signal.

18. The method as claimed in claim 16, wherein:

the reference signal is a discrete signal, preferably a signal that can be evaluated in a binary manner, or a discretely evaluatable signal, or a signal that exhibits a jump.

19. The method as claimed in claim 16, wherein:

an analog signal representing the process variable is ascertained by means of the secondary sensor; and

the process variable ascertained by means of the secondary sensor is converted into the reference signal by means of a measurement transmitter.

20. The method as claimed in claim 16, wherein:

the measurement signal and the at least one reference signal are fed to a signal logging apparatus, which is connected with, respectively includes, the analog to digital converter.

21. The method as claimed in claim 16, wherein:

the connection to the primary sensor can be produced and/or interrupted by means of the signal logging apparatus, preferably as a function of the reference signal.

22. The method as claimed in claim 16, wherein:

the digitized measurement signal representing the process variable is stored by means of an evaluation unit.

23. The method as claimed in claim 16, wherein:

the reaching of a predetermined state of the process variable is transmitted via a signal line between the at least one secondary sensor and the evaluation unit.

24. The method as claimed in claim 16, wherein:

the transmission of the reference signal via the signal line occurs in addition to, preferably parallel to, the transmission of the reference signal to the logging apparatus (H1).

25. The method as claimed in claim 16, wherein:

the process variable is a temperature.

26. An apparatus for determining a process variable, preferably for adjusting, calibrating and/or certification of a primary sensor, comprising:

a primary sensor, which serves for producing an analog measurement signal representing a process variable;

an analog to digital converter, which serves for converting the analog measurement signal into a digital signal representing the measured variable;

at least one secondary sensor, which serves for producing at least one reference signal representing the process variable; and

a control unit, which is connected with said primary sensor and said at least one secondary sensor,

which control unit includes said analog to digital converter and serves, as a function of the point in time, at which the reference signal displays the reaching of a predetermined state of the process variable, especially by reaching a value of the reference signal itself, to;

log the value of the measurement signal of said primary sensor converted by means of said analog to digital converter; and

/or

interrupt the connection between said analog to digital converter and said primary sensor; and

/or

change the sampling rate of the value of the measurement signal of said primary sensor converted by means of said analog to digital converter; and

/or

change a processing in said evaluation unit, especially a measured value averaging, of the value of the measurement signal of said primary sensor converted by means of said analog to digital converter.

27. The apparatus as claimed in claim 26, wherein:

said primary sensor is a sensor element for ascertaining temperature.

28. The apparatus as claimed in claim 27, wherein:

after completed conversion of the primary measurement signal, respectively storing of the primary measurement signal, the connection between said primary sensor and an AD converter is reestablished.

29. The apparatus as claimed in claim 26, further comprising:

first and second secondary sensors are provided, as well as a circuit arrangement between said control unit and said first and second secondary sensors, wherein;

the circuit arrangement combines the reference signals output respectively by said first and second secondary sensors logically with one another and outputs a resulting reference signal to said control unit.

30. The apparatus as claimed in claim 29, wherein:

in said evaluation unit an adjustment is performed based on a value pair formed by the reference signal by means of said primary sensor and the known transition point.