PLC Event Input Module Using IRIG-B for Precise Time Synchronization
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Solution Overview
Problem
Conventional time synchronization methods in power transmission and distribution systems, such as those using GPS or NTP/SNTP, face limitations including high costs, limited expandability, and accuracy issues, especially when dealing with large time differences, making them unsuitable for accurate time synchronization across multiple PLC systems.
Innovation Solution
An event input module configured with a first receiver for external sensor signals, a second receiver for IRIG-B time information, a controller to allocate time information to detected events, and a memory to store this information, utilizing an IRIG-B signal and a timer port for precise time synchronization between PLC systems, thereby simplifying system configuration and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPS receiver is used for time synchronization, then time synchronization capability is achieved, but system cost increases and expandability is limited
Solution Approach 1:
The patent extracts the time synchronization function from the GPS receiver and implements it directly within the event input module using an IRIG-B signal receiver. This eliminates the need for a separate GPS receiver and RS232-RS485 converter, reducing system complexity and cost while maintaining time synchronization capability.
Solution Approach 2:
The patent introduces an IRIG-B signal as an intermediary for time synchronization. The IRIG-B signal contains encoded time information that can be directly received and processed by the event input module, serving as a efficient mediator between time sources and the PLC system without requiring complex conversion hardware.
2Ease of operation
If NTP or SNTP software synchronization is used, then implementation simplicity is improved, but synchronization accuracy deteriorates when time difference is large
Solution Approach 1:
The patent uses the IRIG-B signal to preliminarily synchronize the time at the event input module before events occur. The timer port receives and decodes the IRIG-B signal in advance, ensuring that the module is already synchronized when events are detected, thus avoiding the accuracy problems of NTP/SNTP when large time differences exist.
3Adaptability or versatility
If conventional PLC time synchronization configuration is used, then system compatibility is maintained, but time delay elements reduce synchronization accuracy
Solution Approach 1:
The patent merges the time synchronization function and event detection function into a single event input module. The IRIG-B signal receiver and timer port are integrated with the event input circuitry, eliminating separate synchronization hardware and reducing time delay elements in the signal path.
Solution Approach 2:
The patent replaces the conventional mechanical/software-based time synchronization approach (using GPS receiver and RS232-RS485 conversion) with an electronic IRIG-B signal reception and decoding system. This substitution reduces the number of conversion steps and associated time delays while maintaining compatibility with PLC systems.
Data Source
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AI summary
Disclosed is an event input module, wherein the event input module receives time information which is an IRIG-B signal of a predetermined method from an outside time provider, allocates the time information to a detected event and determines event generation information.