Industrial Controller Global Clock Synchronization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Industrial control systems face significant jitter and network inefficiency due to asynchronous scanning loops, which lead to variable data arrival times and reduced network bandwidth, despite using reliable communication networks like ControlNet, DeviceNet, and EtherNetIP.
Innovation Solution
Implementing a global clock system and profiler to synchronize scanning loops across control elements, ensuring data arrives just before the start of the next cycle, thereby reducing delay and jitter, and optimizing network bandwidth by eliminating redundant transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If asynchronous scanning loops are used for data transmission, then network flexibility and ease of operation are improved, but jitter and delay increase
Solution Approach 1:
The patent introduces a global clock as an intermediary time reference that all control elements synchronize to. This mediator coordinates the asynchronous scanning loops without requiring changes to the flexible network topology, allowing elements to maintain independent operation while achieving synchronized data arrivals through the common time reference.
Solution Approach 2:
The patent changes the time parameter of scanning loops by adjusting their timing based on the global clock reference. Each control element modifies its scanning loop timing parameters to ensure data transmissions are synchronized to arrive at predetermined times, transforming the asynchronous behavior into a synchronized pattern while preserving network flexibility.
2Adaptability or versatility
If asynchronous scanning loops are used, then adaptability of network topology is improved, but network bandwidth utilization deteriorates
Solution Approach 1:
The global clock serves as a mediator that enables efficient bandwidth utilization without constraining network topology. Control elements can be added, removed, or repositioned in the flexible network while the global clock coordination ensures optimal timing of data transmissions, eliminating redundant transmissions and maximizing bandwidth efficiency.
Solution Approach 2:
The patent uses preliminary action by pre-calculating and pre-scheduling data transmission times based on the global clock reference. The profiler determines optimal transmission timings in advance, allowing control elements to send data just-in-time without unnecessary retransmissions, thereby improving bandwidth utilization while maintaining network adaptability.
3Ease of operation
If scanning loops are not synchronized, then ease of operation is improved, but delay and jitter increase
Solution Approach 1:
The patent implements feedback through the global clock synchronization mechanism. Each control element continuously references the global clock timing and adjusts its scanning loop operations based on this feedback. The profiler provides timing information feedback that enables elements to synchronize their transmissions, reducing delay and jitter while maintaining operational simplicity through automatic coordination.
Solution Approach 2:
The global clock creates equipotentiality in the time domain across all control elements. By establishing a common time reference, all elements operate from the same temporal baseline, eliminating timing disparities and synchronization issues that would otherwise increase delay and jitter, while keeping the system easy to operate through uniform timing rules.
Data Source
AI summary
An industrial control system communicating among various control elements via a serial network synchronizes the scanning loops associated with collecting and forwarding data along the network so as to substantially reduce transmission delay and jitter, using synchronization information passed along the network.