Redundant Communication Path in Distributed Control Slave Units
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Solution Overview
Problem
In distributed industrial control systems, communication interruptions between slave units cause failures as only the section before the interruption receives commands, while the section after the interruption is left uncontrolled, leading to potential system failures due to the scarcity of communication ports required for creating redundant paths.
Innovation Solution
A method that creates a redundant path in the reverse communication direction of the slave unit chain, allowing communication frames to be routed from the master control unit to the second slave unit and then through the sub-chains via the redundant path, ensuring continued operation without rerouting or reconfiguration, and allows for rapid calculation and loading of clock offsets by pre-measuring propagation delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the last slave unit is connected to a second port of the master control unit to create a redundant path, then system reliability is improved, but device complexity increases due to requiring additional communication ports
Solution Approach 1:
The second slave unit is configured to perform multiple functions: it serves as a normal slave unit in the chain while simultaneously acting as an intermediate routing point for redundant communication paths. By enabling the second slave unit to forward communication frames between different ports, the system achieves redundancy without adding dedicated redundant components, thus reducing device complexity while maintaining reliability.
Solution Approach 2:
The second slave unit functions as an intermediary device that mediates communication between the master control unit and other slave units through its multiple ports. Instead of directly connecting the last slave unit to the second port of the master control unit, the second slave unit acts as a mediator that forwards frames, thereby creating the redundant path without requiring direct master-to-master connections or additional communication ports.
2Reliability
If communication ports are increased to create redundant paths, then system reliability is improved, but loss of substance increases due to scarcity of communication ports
Solution Approach 1:
The patent merges the functionality of redundant path creation with the existing slave unit structure. The second slave unit's communication ports are utilized for dual purposes: normal chain communication and redundant path routing. This merging approach allows the system to achieve redundancy without consuming additional communication ports, thereby preventing the loss of substance associated with port scarcity.
Solution Approach 2:
The system changes the operational parameters of the second slave unit's communication ports by configuring them to handle both standard chain communication and redundant path routing. By modifying how existing ports are utilized rather than adding new ports, the system maintains reliability while avoiding the depletion of communication port resources.
Data Source
Figure 1a~1b
Figure 1c~1d
Figure 2a
AI summary
A method of connecting a plurality of first slave units in a distributed control system, a distributed control system and a master control unit. The system comprises a master control unit, a plurality of first slave units. The system further comprises a second slave unit which comprises a first communication port, a second communication port and a third communication port, wherein each communication port has an input and an output. In the second slave unit the input of the first communication port is internally communicatively connected to the output of the second communication port, the input of the second communication port is internally communicatively connected to the output of the third communication port, and the input of the third communication port is internally communicatively connected to the output of the first communication port. The method further comprises forming a chain of first slave units from the plurality of first slave units, communicatively connecting the master control unit to the first communication port of the second slave unit, communicatively connecting a first communication port of a front slave unit of said chain of first slave units to the second communication port of the second slave unit and communicatively connecting a second communication port of a rear slave unit of said chain to the third communication port of the second slave unit.