Duplexed Field Controller Clock Synchronization
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Solution Overview
Problem
Existing duplexed field controllers face challenges in minimizing control authority switching time and scan speed, leading to potential interruptions and inaccuracies in control operations.
Innovation Solution
A duplexed field controller with synchronized application clocks and an update control unit that adjusts the second application clock after authority switch, preventing counting omission or double counting by determining the timer clock alignment between CPUs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control authority is switched from the first control unit to the second control unit, then the reliability of control is improved, but the control continuity may be interrupted and scan jitter increases
Solution Approach 1:
The patent applies preliminary action by pre-synchronizing the second application clock with the first application clock before the control authority switch occurs. The update control unit monitors the clock relationship and prepares the standby control unit's timing in advance, ensuring that when the switch happens, the second control unit is already synchronized and ready to continue control without interruption or jitter.
2Measurement precision
If the application clock is updated continuously during control authority switching, then the timing accuracy is maintained, but counting omission or double counting may occur
Solution Approach 1:
The patent applies preliminary anti-action by having the update control unit detect the relationship between the first and second application clocks before the switch, and preemptively prevent the problematic update of the second application clock. When the first clock is ahead of the second clock at the moment of switch, the update control unit intentionally bypasses the update that would cause double counting, thus counteracting the potential error before it occurs.
3Productivity
If the control scan speed is increased, then the productivity is improved, but the control continuity becomes more difficult to maintain during switching
Solution Approach 1:
The patent enables high-speed scanning while maintaining continuity by pre-synchronizing the standby control unit's application clock before the switch. This preliminary synchronization ensures that even at increased scan speeds, the transitioning control unit is already aligned in timing, allowing seamless handover without interruption or jitter, thus maintaining control continuity at higher productivity levels.
Data Source
AI summary
There is provided a duplexed field controller. The duplexed field controller includes: first and second control units between which a control authority is switchable; a first application clock that is updated based on a reference clock so as to define a timing of an application operation of the first control unit; a second application clock that is updated based on the reference clock so as to define a timing of an application operation of the second control unit; and an update control unit that bypasses the first update of the second application clock after switching of the control authority, if the first application clock is ahead of the second application clock when the control authority is switched from the first control unit to the second control unit.