Current Loop Communication System for Automatic Slave Device Configuration

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Solution Overview

Problem

Current communication systems in automation technology, particularly those used in safety-related applications, face challenges in automatically detecting and configuring systems, especially in ensuring reliable data transmission and power supply without interference, as existing systems often combine data and power transmission over a single bus, which is not suitable for safety-critical environments.

Innovation Solution

A communication system utilizing a current loop for data transmission between a master device and slave devices, where the master device injects a constant quiescent current, and switching devices are used to modulate this current for data exchange, allowing for automatic system configuration detection by evaluating changes in current and voltage levels, ensuring robustness and safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single bus is used to carry both power and data, then device complexity is reduced, but reliability deteriorates because the system is not suitable for safety-related applications

Engineering Contradiction:
Improvesystem complexityVSAvoidsafety reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent segments the transmission medium into separate functions: a current loop dedicated for data transmission and a separate power supply unit for power delivery. This separation ensures that data communication and power supply operate independently, preventing interference and enabling safety-critical applications while maintaining system reliability.

Inventive Principle:
Principle #1Segmentation

2Reliability

If manual configuration is used for system setup, then reliability is improved through careful setup, but productivity deteriorates due to time-consuming configuration

Engineering Contradiction:
Improveconfiguration reliabilityVSAvoidsystem setup speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent implements preliminary action through automatic device recognition and configuration. When a device is connected to the current loop, the master device automatically detects the device type, determines the number of devices, and configures the system parameters without requiring manual intervention. This preliminary automatic configuration maintains reliability while dramatically improving setup productivity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system performs self-service through automatic self-configuration. Each device on the current loop is automatically recognized and configured by the master device based on electrical characteristics and communication protocols. The system determines device types, addresses, and operational parameters autonomously, eliminating the need for manual configuration while ensuring reliable setup.

Inventive Principle:
Principle #25Self-service

3Loss of information

If switching devices are added for current modulation, then data transmission capability is improved, but device complexity increases

Engineering Contradiction:
Improvedata transmission accuracyVSAvoidswitching device complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The patent merges the switching function with the existing device structure. The switching devices (first switching device in master, second switching device in slave) are integrated into the current loop architecture, allowing current modulation for data transmission without adding significant external complexity. The switching elements work in coordination to encode data while maintaining a relatively simple overall system structure.

Inventive Principle:
Principle #5Merging (Combining)

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

Enables reliable, efficient, and safe data transmission and system configuration detection, even in fault conditions, by using current modulation and automatic detection mechanisms, thus enhancing the reliability and robustness of the communication system for safety-related applications.

Implementation Method 1

data transmission by current modulation between a master device and at least one slave device

Methodology Applied
Scientific EffectCurrent modulation:

Implementation Method 2

a first switching device (110) switchable into a current loop (140) and controllable by the first evaluation and control unit (60), which is configured to open and close the current loop (140) for data transmission

Methodology Applied
Scientific EffectElectrical switching:

Implementation Method 3

automatic system configuration detection by evaluating changes in current and voltage levels

Methodology Applied
Scientific EffectElectrical measurement:

Data Source

PatentEP3516828B1Communication system for current-modulated data transmission via a current loop
Publication Date: 2023.02.15 PHOENIX CONTACT GMBH & CO KG
  • EP3516828B1 patent drawingFigure 1
  • EP3516828B1 patent drawingFigure 2
  • EP3516828B1 patent drawingFigure 3

AI summary

The invention relates to a communication system (10) for current-modulated transmission of data via a current loop (140) into which a master device (20) and at least one slave device (1501, 150n) are looped. The at least one slave device (1501, 150n) has a switching device (2501, 250n) that is actuatable by an evaluation and control device (1601, 160n) and that is configured to short a current loop (140) in the closed state, wherein the evaluation and control unit (1601, 160n) is configured to temporarily close and then reopen the switching device (2501, 250n) during a system configuration detection phase. An evaluation and control unit (60) of the master device (20) is configured to detect when the at least one slave device (1501, 150n) is looped into the current loop (140).