Automation Network Clock Sequencing for Jitter-Free Time Stamps

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Solution Overview

Problem

In automation communication networks, clock synchronization using integer counter values can lead to deviations in clock increments, causing jitter and incorrect time stamps due to non-integer period durations, which disrupts synchronous data exchange.

Innovation Solution

A method where the internal clock is incremented using a sequence of integer increments defined such that their sum corresponds to an integer multiple of the period duration, minimizing deviations and adapting the clock to the data exchange frequency, thereby eliminating the need for clock domain transformation and reducing jitter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If clocks are incremented at the clock frequency, then the data exchange can be synchronized, but the count values deviate from multiples of the period duration causing jitter

Engineering Contradiction:
Improvesynchronization reliabilityVSAvoidtime stamp precision
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The increment operation is segmented into multiple smaller steps instead of a single large increment. The sequence divides the total increment into intermediate values that are applied sequentially, allowing the clock to pass through intermediate states that minimize deviation from ideal timing points.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The sequence of increment values is pre-calculated and stored before the clock operation begins. This preliminary preparation allows the system to execute the optimized increment sequence without real-time computation delays, ensuring that timing deviations are minimized from the start of each clock cycle.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If clock domain transformation is performed, then the clock frequency can be adapted, but the transformation delay causes time deviation from reference time

Engineering Contradiction:
Improveclock frequency adaptabilityVSAvoidtime stamp accuracy
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The clock domain transformation function is extracted and implemented directly within the clock incrementing logic itself, rather than as a separate transformation stage. This integration eliminates the need for distinct transformation blocks and their associated delays.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The frequency adaptation and time stamping functions are merged into a single unified process. The clock increment sequence simultaneously achieves frequency adaptation and generates accurate time stamps, eliminating the sequential execution of separate transformation and timestamping operations.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3864780B1Method of operating a communication-node in an automation communication network
Publication Date: 2022.05.04 BECKHOFF AUTOMATION GMBH
  • EP3864780B1 patent drawingFigure 1
  • EP3864780B1 patent drawingFigure 2
  • EP3864780B1 patent drawingFigure 3

AI summary

A network participant (7) of an automation communication network (1) is provided in order to exchange data with additional network participants (2) in the automation communication network (1) at a defined clock frequency. The network participant (7) has an internal clock (8) for synchronizing the data exchange with at least one additional network participant (7). The internal clock (8) is provided in order to provide a time as an integer count value. The clock frequency is defined such that a period duration per cycle of the internal clock (8) cannot be represented by an integer count value. A method for operating the network participant (7) in the automation communication network (1) comprises the following method step: The internal clock (8) is incremented by means of a defined sequence of integer increments. The sequence of integer increments is defined such that a sum of the integer increments corresponds to an integer multiple of the period duration.