Measuring Channel Reference Switching for Independent Verification

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Solution Overview

Problem

Existing measuring devices with multiple channels lack reliable methods to verify the functionality of each channel, as known plausibility checks using D/A converters do not provide independent verification, leading to potential inaccuracies due to component aging and environmental influences.

Innovation Solution

A measuring device with at least two channels, where one channel acts as a safe measuring channel with a multiplexer that switches between measuring voltage and reference voltage, and a logic unit in another channel generates the reference voltage independently, allowing for comprehensive checking of the input range and detection of errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a plausibility check using a D/A converter is provided in the measuring channel, then the measuring channel can be checked for basic functionality, but independent verification is not possible and reliable checking is not guaranteed

Engineering Contradiction:
Improvechecking reliabilityVSAvoidverification independence
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A multiplexer is introduced as an intermediary component that allows the same analog input of an A/D converter to be connected to different voltage sources (measuring voltage or reference voltage). This enables independent verification by switching between measurement mode and test mode without requiring separate verification hardware, thus improving checking reliability while avoiding increased device complexity

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The A/D converter's analog input is designed to universally accept both measuring voltage and reference voltage through the multiplexer. This multi-functionality allows a single A/D converter to serve both measurement purposes and self-verification purposes, enabling reliable checking without adding separate verification channels

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If two independent channels are provided with multiplexer switching for test signals, then comprehensive checking is possible, but device complexity and cost increase

Engineering Contradiction:
Improvechecking reliabilityVSAvoidchannel quantity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Each measuring channel is equipped with a multiplexer that enables it to perform self-verification by switching its own analog input between measuring voltage and reference voltage. The channel uses its own A/D converter and logic unit for both measurement and testing, eliminating the need for separate independent verification channels and reducing overall device complexity while maintaining high checking reliability

Inventive Principle:
Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables reliable and independent verification of measuring channel functionality, ensuring accuracy and reliability by using a reference voltage generated from a second channel, which can be repeated and applied across all channels, thereby detecting errors within a specific range of analog voltages.

Implementation Method 1

the multiplexer being able to switch the analog voltage between a measuring voltage and a reference voltage

Methodology Applied
Scientific EffectElectrical switching:

Implementation Method 2

each measuring channel comprising an A/D converter for converting an analog voltage into a digital voltage value

Methodology Applied
Scientific EffectAnalog-to-digital conversion:

Implementation Method 3

the reference generator is designed to provide the reference voltage based on the digital value applied to it

Methodology Applied
Scientific EffectDigital-to-analog conversion:

Data Source

PatentEP2525232B1Measuring device with a secure measuring channel
Publication Date: 2018.06.20 PHOENIX CONTACT GMBH & CO KG
  • EP2525232B1 patent drawingFigure 1
  • EP2525232B1 patent drawingFigure 2~3

AI summary

The device has measuring channels (2a,2b) which are provided with analog-to-digital (A/D) converters (4a,4b) for converting of analog voltage value to digital voltage value. The logic units (5a,5b) are connected with A/D converters, in order to receive digital voltage value. A reference generator is provided to generate the reference voltage (Uref1,Uref2), based on digital voltage value. The multiplexers (3a,3b) switch analog voltage between the measuring voltage (UMess1,UMess2) and the reference voltage.