Event Buffering for Guaranteed Batch Delivery in Process Control
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Solution Overview
Problem
Process control systems in industries like chemical, pharmaceutical, and petrochemical production face challenges in ensuring complete batch records due to intermittent communication links and event loss, which is critical for regulatory compliance and quality assurance.
Innovation Solution
A method and apparatus for guaranteed batch event delivery in process control systems, where events are generated, buffered, and communicated with unique identifiers, allowing for event recovery and alarm generation when desired events are not received, ensuring complete records through mechanisms like event buffering and supervisory server-initiated recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If events are communicated directly without buffering, then communication speed is improved, but event loss occurs during communication interruptions
Solution Approach 1:
The controller buffers events locally before they are communicated to the supervisory server, preparing them in advance for transmission. This preliminary action ensures that events are not lost during communication interruptions, as they are already stored in the buffer and can be transmitted when the communication link is restored.
Solution Approach 2:
An event buffer acts as an intermediary between the controller and the supervisory server. This buffer temporarily stores events, allowing the system to decouple the communication timing from the event generation timing, thus preventing event loss during communication interruptions while maintaining efficient data transfer.
2Reliability
If events are buffered for recovery, then event delivery reliability is improved, but device complexity increases
Solution Approach 1:
The event buffer serves multiple functions: it stores events temporarily during communication, queues events for transmission, and enables recovery of lost events. By making the buffer multi-functional, the system achieves reliable event delivery without adding separate dedicated components for each function, thus limiting the increase in system complexity.
Solution Approach 2:
The system automatically detects missing events using unique identifiers and initiates recovery processes without requiring manual intervention. The supervisory server can autonomously request and receive recovered events from the controller's buffer, reducing the need for additional complex monitoring and management systems.
3Loss of information
If event recovery is implemented, then completeness of batch records is improved, but communication overhead increases
Solution Approach 1:
The system recovers only the specific events that are missing, identified by gaps in the sequence of unique identifiers, rather than retransmitting all events. This partial action approach ensures batch record completeness while minimizing unnecessary communication overhead and time consumption.
Solution Approach 2:
The supervisory server monitors the sequence of unique identifiers received from the controller and provides feedback when gaps are detected. This feedback mechanism triggers selective recovery of only the missing events, ensuring complete batch records while optimizing communication efficiency by avoiding redundant data transmission.
Data Source
AI summary
A controller controls one or more process elements in a process control system. The controller also generates and buffers multiple events associated with operation of the controller. Each event is associated with a unique identifier, such as a numerical identifier. A supervisory device receives at least some of the events from the controller. The supervisory device determines if any of the events have not been received from the controller based on the unique identifiers. The supervisory device also initiates an event recovery if at least one of the events has not been received from the controller. During the event recovery, the controller recovers at least one event, such as any event having a numerical identifier greater than a numerical identifier identified by the supervisory device. The controller communicates the at least one recovered event to the supervisory device during the event recovery.