Serial Asynchronous Databus Topology Determination

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Solution Overview

Problem

Existing methods for determining the topology of serial asynchronous databuses, such as fieldbus systems, are inaccurate and disruptive to ongoing operations, especially at higher baud rates, due to reliance on reflection measurements that require an inoperative bus and are affected by unknown influence factors like contact resistances.

Innovation Solution

A method that calculates average response times for request and response telegrams at multiple measurement sites along the databus, allowing for precise determination of signal run times and distances between bus subscribers during regular operation, without the need for special wiring configurations or measurement signals, using existing data traffic telegrams like FDL status telegrams.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If reflection-based run time measurement is used to determine cable length, then measurement precision is improved, but the bus must be inoperative and measurement signals interfere with ongoing operation

Engineering Contradiction:

Improvecable length measurement precisionVSAvoidbus operation continuity

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The method uses the bus subscribers' own response telegrams to the request telegrams as the measurement signals. The subscribers respond to the request telegrams with response telegrams that contain the necessary timing information, eliminating the need for external measurement signals and allowing the bus to remain operational during measurements.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The measurement process continues the normal communication flow by using existing request and response telegram exchanges. The measurement is performed during regular bus operation without interrupting or stopping the bus, maintaining continuous useful action while obtaining measurement data.

Inventive Principle:

Principle #20Continuity of useful action

2Ease of operation

If DC current measurements are used to determine bus topology, then ease of operation is improved, but measurement precision deteriorates due to unknown influence factors like contact resistances

Engineering Contradiction:

Improvemeasurement simplicityVSAvoiddistance measurement accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The method replaces electrical resistance-based measurements with time-based measurements. Instead of measuring current and resistance to determine distance, the system measures the time of flight of signals and calculates distance from the speed of light, eliminating the influence of contact resistances and electrical interference.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The method introduces time as an intermediary parameter to determine distance. By measuring the time difference between request and response telegrams and using the speed of light as a constant, the system can calculate distance without being affected by electrical properties like contact resistances that plague direct electrical measurement methods.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If active measurement methods are used during regular bus operation, then productivity is improved, but measurement precision deteriorates due to signal interference with communications

Engineering Contradiction:

Improvemeasurement execution during operationVSAvoiddistance measurement accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The bus subscribers serve as both the communication entities and the measurement targets. They respond to request telegrams with response telegrams that naturally carry the timing information needed for measurement, eliminating the need for separate measurement signals that would cause interference.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The method merges the communication function and measurement function into a single process. The same request and response telegram exchanges that perform data communication also provide the timing information for distance measurement, combining two functions without adding interfering measurement signals.

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

This method provides accurate and reliable topology determination even at higher baud rates, increasing precision with more measurements, and does not interfere with ongoing data communication, offering efficient and precise distance calculations between bus subscribers.

Implementation Method 1

the time differences between the transmission of a particular request telegram and the reception of the related response telegram are determined

Methodology Applied

Scientific EffectTime of Flight: Time of Flight

Data Source

PatentUS9442880B2Method for determining the topology of a serial asynchronous databus

Publication Date: 2016.09.13 SOFTING

AI summary

A computer-implemented method for determining the topology of a serial asynchronous data bus, to which at least a first bus subscriber and a second bus subscriber are connected, which subscribers communicate via a prescribed bus access protocol.