Distributed Control System with Bidirectional Diagnosis Lines
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Solution Overview
Problem
Conventional distributed control systems require extensive operator effort to identify and recover from anomalies due to the inability to specify the location of issues within the system, leading to prolonged recovery times.
Innovation Solution
A distributed control system with active and backup transmission lines of opposite directions, allowing for diagnosis command and acknowledgment-response transmission, enables accurate anomaly detection and location specification through ring, bus, or star topology configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single transmission line is used for diagnosis command transmission, then the system structure is simple, but the anomaly location cannot be specified
Solution Approach 1:
The transmission line is segmented into multiple directional lines (first transmission line and second transmission line) with opposite transmission directions. This segmentation allows the system to determine anomaly locations by comparing which directional line successfully transmits diagnosis commands, thereby resolving the contradiction between structural simplicity and anomaly location precision.
Solution Approach 2:
The system adds a dimensional aspect by introducing bidirectional transmission capability through two opposite-directional lines. This dimensional change enables the system to identify anomaly locations by analyzing transmission success/failure in different directions, transforming a single-line unidirectional system into a multi-dimensional diagnostic network.
2Reliability
If the entire system is checked when an anomaly is detected, then comprehensive diagnosis is achieved, but the recovery time becomes very long
Solution Approach 1:
The system performs preliminary diagnostic actions by continuously transmitting diagnosis commands through bidirectional lines before actual anomalies affect operations. When anomalies occur, the pre-established directional transmission paths enable immediate location identification, eliminating the need for comprehensive system checks and significantly reducing recovery time while maintaining diagnostic reliability.
Solution Approach 2:
The system implements feedback mechanisms where acknowledgment responses are transmitted back through the opposite directional line. This feedback loop provides real-time information about transmission success/failure, enabling the master PLC to quickly identify anomaly locations without exhaustive checking, thus balancing diagnostic completeness with rapid recovery.
Data Source
AI summary
A distributed control system includes a plurality of PLCs which are connected together via active and backup transmission lines which are opposite in transmission direction. Each of the PLCs includes a diagnosis command sending program for sending a diagnosis command, via a diagnosis-command transmission line, which is one of the active transmission line and the backup transmission line, to a PLC located downstream on the diagnosis-command transmission line; and an acknowledgment returning program, operable upon receipt of the diagnosis command, for returning an acknowledgement response for the diagnosis command, via an acknowledgment-response transmission line, which is the other of the active transmission line and the backup transmission line, to a PLC located downstream on the acknowledgment-response transmission line.