Optocoupler HART Signal Isolation for Compact Field Transmitters
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Solution Overview
Problem
Existing signal transmission systems between field devices and higher-level units in process automation technology face challenges in efficiently combining analog and digital signals while maintaining galvanic isolation, often requiring large space for transformer-based solutions.
Innovation Solution
The use of an optocoupler arrangement for signal transmission, which converts and optically transmits data signals between field devices and higher-level units, replacing traditional HART transformer setups to achieve galvanic isolation with high measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a HART transformer is used to transmit the HART signal, then galvanic isolation is achieved, but a lot of space is required
Solution Approach 1:
The patent replaces the mechanical/electromagnetic transformer-based galvanic isolation system with an optical isolation system using optocouplers. The HART signal is converted to optical signals that transmit information across the isolation barrier without requiring large transformer components, thus achieving galvanic isolation while significantly reducing space requirements
Solution Approach 2:
The patent introduces an optical intermediary (optocoupler) between the primary and secondary sides of the isolation barrier. The optocoupler converts electrical signals to optical signals and back, serving as a mediator that achieves galvanic isolation without the space-consuming transformer architecture
2Productivity
If analog and digital signals are combined in a two-wire process control loop, then communication efficiency is improved, but signal interference may occur
Solution Approach 1:
The optocoupler acts as an intermediary that separates the analog and digital signal paths while maintaining efficient communication. By converting signals to the optical domain for transmission across the isolation barrier, the system prevents electrical interference while preserving the benefits of combined analog-digital communication
Solution Approach 2:
The patent substitutes electrical signal transmission with optical signal transmission across the isolation barrier. This replacement eliminates electromagnetic interference between analog and digital signals while maintaining the efficiency of combined communication modes
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 approach allows for compact and efficient transmission of both main process variables and additional data, maintaining galvanic isolation and achieving high measurement accuracy, while enabling bidirectional communication in compliance with the HART standard.
Implementation Method 1
an optocoupler arrangement is used to transmit the data signal... The signal is then transmitted optically digitally in this optocoupler arrangement
Implementation Method 2
The optocoupler arrangement is configured to transmit the data signal between the first conversion arrangement and the second conversion arrangement
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
The present invention relates to a signal transmission system for transmitting a main process variable and further data between a field device and a higher-level unit, comprising a first conversion arrangement, a second conversion arrangement, and an optocoupler arrangement (10, 10a, 10b) connected between the first conversion arrangement and the second conversion arrangement, wherein the first conversion arrangement is configured to convert at least the further data exchanged between the field device and the higher-level unit into a data signal such that it can be transmitted via the optocoupler arrangement (10, 10a, 10b); wherein the optocoupler arrangement (10, 10a, 10b) is configured to transmit the data signal between the first conversion arrangement and the second conversion arrangement;and wherein the second conversion arrangement is configured to convert the data signal to the additional data exchanged between the field device and the higher-level unit and to transmit it to the field device. Furthermore, the invention relates to a method for transmitting a main process variable and additional data between a field device and a higher-level unit.