Method for operating a field device and corresponding field device

Patent metadata

Field	Value
Publication number	US-2016294375-A1
Application number	US-201615086301-A
Country	US
Kind code	A1
Filing date	Mar 31, 2016
Priority date	Apr 1, 2015
Publication date	Oct 6, 2016
Grant date	—

Abstract

A method for operating a field device, and a field device that is operated according to the method, in which a measured value is generated, the measured value being assigned a current set point, a target current signal being issued depending on the current set point, wherein an actual current signal is fed back and the target current signal is compared to the actual current signal. To provide more exact comparison of signals a cross-correlation of the target current signal with the actual current signal is formed for comparison.

First claim

What is claimed is:

1 . A method for operating a field device, comprising:
generating a measured value, assigning a current set point to the measured value, issuing a target current signal depending on the current set point, and feeding back an actual current signal and comparing the target current signal to the actual current signal, wherein a cross-correlation of the target current signal with the actual current signal is formed for the comparison.

2 . The method according to claim 1 , wherein an auto-correlation one of the target current signal and of the actual current signal is formed, and wherein a deviation of the correlated signals is calculated in that the values of the cross-correlation of the actual current signal with the target current signal are related to the value of the auto-correlation of said one of the current set point and of the auto-correlation of the actual current signal.

3 . The method according to claim 1 , wherein the target current signal is digitized with a first sampling rate and the actual current signal is digitized with a second sampling rate that is set at a fixed relation to the first sampling rate.

4 . A field device, comprising:
at least one signal outlet and at least one control component which generates a measured value and assigns a current set point to the measured value, generates a target current signal depending on the current set point and issues the target current signal via the signal outlet and wherein the control component imports an actual current signal and compares the target current signal to the actual current signal, the control component forming a cross-correlation of the target current signal with the actual current signal for comparison.

5 . The field device according to claim 4 , wherein a converting device is provided for conversion of digital signals to analog signals.

6 . The field device according to claim 5 , wherein an analog filter is connected behind the converting device.

7 . The field device according to claim 6 , wherein the analog filter is a low pass filter having a cutoff frequency less than or equal to 25 Hz,

8 . The field device according to claim 5 , wherein a digital filter is provided for filtering the target current signal.

9 . The field device according to claim 4 , wherein an analog-digital converter is provided that digitizes the imported actual current signal.

Assignees

• Krohne Messtechnik Gmbh

Inventors

• Kunze Johannes

Classifications

• G08C19/02

  in which the signal transmitted is magnitude of current or voltage (G08C19/36, G08C19/38 take precedence) · CPC title

• G05B23/024

  Quantitative history assessment, e.g. mathematical relationships between available data; Functions therefor; Principal component analysis [PCA]; Partial least square [PLS]; Statistical classifiers, e.g. Bayesian networks, linear regression or correlation analysis; Neural networks · CPC title

• G05B19/0423

  Input/output · CPC title

• H03K5/24 Primary

  the characteristic being amplitude · CPC title

• H03M1/0626

  by filtering · CPC title