Field Device Time Stamping With Control Unit Clock Drift Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Field devices in process automation face challenges with time recording precision, as cyclical correction of timers requires infrastructure access to a time server, which is often unavailable in industrial settings, hindering reliable time-stamped data collection and analysis.
Innovation Solution
A method that detects and corrects the clock drift between a field device's internal timer and a control unit's timer, allowing data to be saved with a corrected time stamp, enabling time synchronization without relying on external infrastructure, and facilitates data analysis across different devices and time zones by converting timestamps to universal time coordinated (UTC).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cyclical correction of timers is performed by comparing with a reference clock using communication protocols, then time recording precision is improved, but infrastructure dependency increases and reliability deteriorates when time server access is unavailable
Solution Approach 1:
The control unit acts as an intermediary time reference for multiple field devices. Instead of each field device independently accessing a time server, the control unit maintains the time reference and provides timing information to all connected field devices, eliminating the need for direct infrastructure access by individual devices.
Solution Approach 2:
Multiple field devices share a common time reference through the control unit. The timing function is merged at the control unit level rather than being distributed across multiple independent field devices, reducing overall infrastructure dependency while maintaining synchronization precision.
2Measurement precision
If infrastructure to a time server is provided for cyclical correction, then time synchronization accuracy is improved, but device complexity and network requirements increase
Solution Approach 1:
The time server infrastructure requirement is extracted from individual field devices and consolidated at the control unit level. This removes the complex network infrastructure requirement from each field device while maintaining centralized time synchronization accuracy.
3Ease of operation
If internal timers of field devices are used for time stamping, then autonomy and ease of operation are improved, but time recording precision deteriorates due to clock drift
Solution Approach 1:
The control unit provides periodic timing feedback to field devices by including accurate time information in communication cycles. Field devices use this feedback to correct their internal timer drift while maintaining operational autonomy and simple time stamping procedures.
Data Source
AI summary
A method for the time-synchronized processing of data of a field device of process automation, in which the data and/or data changes are saved together with an internal time stamp of an internal timer of the field device in a memory of the field device; during the reading process of the data from the field device, a path difference being detected of the internal timer of the field device and a timer of the control unit by which the data is read, the internal time stamps are corrected by the path difference, and are saved as corrected time stamps together with the data.