Backplane Time Synchronization Over Passive Base Plates
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Solution Overview
Problem
Existing industrial control systems face challenges in efficiently synchronizing I/O modules with a cluster manager over half-duplex communication lines while maintaining real-time constraints and minimizing the risk of collisions and latency.
Innovation Solution
A system utilizing unidirectional communication lines and passive base plates for synchronization, employing a time-aware scheduler and synchronized clocks to enable reliable, low-cost synchronization without active components, allowing communication between I/O modules and the cluster manager while respecting real-time constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard stack in switch transmits before synchronization, then communication can start initially, but measurement errors increase and synchronization reliability deteriorates
Solution Approach 1:
The patent applies preliminary action by establishing synchronization before enabling communication. The cluster manager and I/O modules perform synchronization handshaking and timestamp alignment before any data transmission occurs on the multipoint communication line, ensuring that all devices are synchronized before communication begins, thus eliminating measurement errors while maintaining reliability
Solution Approach 2:
The patent implements feedback through a bidirectional synchronization protocol where the cluster manager sends synchronization requests and I/O modules respond with their timestamp information. This feedback loop allows the cluster manager to adjust timing and confirm synchronization status, reducing measurement errors while enhancing synchronization reliability through continuous verification
2Device complexity
If multipoint communication line is used for synchronization, then device complexity is reduced, but collision risk increases and real-time constraints cannot be guaranteed
Solution Approach 1:
The patent applies periodic action by implementing time-sliced communication on the multipoint line. The cluster manager allocates specific time windows for different I/O modules to transmit data, creating a periodic schedule that eliminates collisions while maintaining the simplicity of the shared communication line. This time-division multiplexing ensures real-time constraints are met without increasing device complexity
Solution Approach 2:
The patent uses the cluster manager as an intermediary that controls access to the multipoint communication line. The cluster manager mediates all communications by granting transmission permissions during synchronized time windows, preventing collisions among I/O modules while keeping the communication infrastructure simple. This intermediary control ensures reliability without requiring complex point-to-point connections
3Reliability
If active components are used in backplane for communication, then communication reliability improves, but cost increases and synchronization precision deteriorates due to path delay
Solution Approach 1:
The patent extracts active communication components from the backplane, using only passive base plates for signal distribution. By removing active components that introduce variable path delays, the system achieves deterministic timing where all I/O modules receive synchronization signals simultaneously through the passive backplane, eliminating synchronization precision issues while maintaining reliability through the standardized synchronization protocol
Solution Approach 2:
The patent replaces active electronic communication systems in the backplane with a passive signal distribution architecture. Instead of using active components that require path delay calculations and compensations, the system uses passive base plates that distribute synchronization signals uniformly to all modules, substituting complex active management with simpler passive distribution that inherently provides deterministic timing
Data Source
AI summary
An industrial system for controlling backplane communication, including:a cluster manager including a primary switch linked to a primary control module,at least one Input/Output, I/O, module including a secondary switch linked to a secondary control module,a unidirectional communication line linking the cluster manager to the at least one IO module through passive base plates,wherein the cluster manager includes a transmission port and a reception port on the unidirectional communication line and the at least one Input/Output module includes a reception port on the unidirectional communication line,wherein the primary control module is configured to generate a pulse via the transmission port on the unidirectional communication line,wherein, upon reception of the pulse, the primary control module is configured to create a primary timestamp from a primary clock of the primary switch and the secondary control module is configured to create a secondary timestamp from a secondary clock of the secondary switch,wherein the primary control module is configured to send a message via the transmission port on the unidirectional communication line to the secondary control module, the message including the primary timestamp,wherein, upon reception of the message, the secondary control module is configured to synchronize the secondary clock with the primary clock based on the received primary timestamp and secondary timestamp.