Transmitter Relative-Time Timer for Accurate Timestamping
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Solution Overview
Problem
Existing data transmitters in process control systems face challenges in accurately providing timestamps without the need for a real-time clock, as battery backups are costly and power-intensive, and continuous power supply is not always feasible, leading to potential timestamp errors if the clock loses power.
Innovation Solution
A transmitter with a relative-time timer that resets to a non-zero baseline time when power is provided, generating a relative-time timestamp based on the elapsed on-time, which can be converted to a real-time timestamp by the control system, eliminating the need for a real-time clock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a real-time clock is used to provide accurate timestamps, then timestamp accuracy is improved, but power consumption increases and battery backup is required
Solution Approach 1:
The timestamping function is segmented into two parts: the transmitter provides relative-time stamps based on its operational timer, and the control system converts these to absolute timestamps using its own real-time clock. This segmentation allows the transmitter to avoid maintaining a real-time clock while still providing accurate timestamping capability through collaboration with the control system.
Solution Approach 2:
Relative-time stamps serve as an intermediary mechanism between the transmitter's operational timer and the control system's real-time clock. The transmitter measures elapsed operational time independently, and the control system acts as a mediator to convert this relative time into absolute timestamps, eliminating the need for the transmitter to maintain continuous power for timekeeping.
2Reliability
If a real-time clock with battery backup is used, then timestamp accuracy during power outages is improved, but device complexity and cost increase
Solution Approach 1:
The real-time clock function is extracted from the transmitter and relocated to the control system. The transmitter only maintains a simple operational timer that measures elapsed time since startup, while the control system handles the conversion to absolute timestamps. This extraction eliminates the need for battery backup in the transmitter while maintaining timestamp reliability.
Solution Approach 2:
The control system creates a copy of the timestamping function by receiving relative-time data from the transmitter and converting it to absolute timestamps using its own real-time clock. This copying approach allows the transmitter to avoid the complexity of battery-backed real-time clocks while ensuring timestamp accuracy through the control system's timekeeping capability.
3Measurement precision
If continuous power is provided to maintain real-time clock accuracy, then timestamp accuracy is improved, but power consumption increases
Solution Approach 1:
The timer baseline is made dynamic rather than fixed. The relative-time timer resets to a non-zero baseline value when the transmitter starts up, allowing the system to adapt to power cycling conditions. This dynamic baseline adjustment enables accurate relative-time measurement without requiring continuous power supply to maintain a fixed real-time clock.
Solution Approach 2:
The relative-time timer is designed as a simple, low-power component that does not require continuous power maintenance like a real-time clock. It measures elapsed operational time since the last startup or baseline reset, providing sufficient timestamp accuracy for operational monitoring without the energy overhead of maintaining continuous timekeeping.
4Use of energy by moving object
If a relative-time timer with non-zero baseline is used, then power consumption is reduced, but determining power cycle status becomes more difficult
Solution Approach 1:
The system implements feedback by monitoring changes in the relative-time baseline value. When the baseline changes from its initial non-zero value, this indicates a power cycle event has occurred. The control system uses this baseline change feedback to detect power cycles and adjust its timestamp conversion accordingly, making power cycle detection straightforward despite the non-zero baseline.
Data Source
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AI summary
A transmitter (102) is provided. The transmitter (102) comprises a first communication interface (112) for receiving data. The transmitter (102) also comprises a timer (104) for measuring a relative-time and a processing system (110) for providing the data with a relative-time timestamp. A second communication interface (105) is provided for outputting the relative-time timestamped data.