PLC Variable Exchange via Association Module Without Restarts
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Solution Overview
Problem
Current process control units require system stops, recompilation, and restarts for updates or modifications of control processes due to their monolithic architecture and fixed interprocess data exchange, lacking flexibility and scalability.
Innovation Solution
Implementing an intermediate allocation module for interprocess data exchange, allowing dynamic reconfiguration of process variable assignments without stopping the system, by using an assignment module that determines the recipient of process variables based on an assignment rule.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If process variables are copied from one process image to another using prior art methods, then interprocess data exchange is achieved, but the system requires complex memory management with multiple memory areas and copying mechanisms increasing device complexity
Solution Approach 1:
The patent extracts the process variable data from the complex memory management system by implementing a message buffer that directly receives process variables from the process image without requiring traditional memory copying mechanisms. This extraction simplifies the memory management architecture while maintaining data exchange functionality.
Solution Approach 2:
The patent introduces a message buffer as an intermediary component between process images. This mediator receives process variables directly from the process image and makes them available to other processes, eliminating the need for complex memory copying and management while enabling efficient interprocess communication.
2Loss of information
If process images are updated frequently to enable real-time data exchange, then data freshness is improved, but the system stability deteriorates due to potential inconsistencies during updates
Solution Approach 1:
The patent implements preliminary action by pre-allocating fixed memory areas for process variables within the process image structure. This pre-organization allows data to be prepared and staged for exchange before actual updates occur, enabling real-time data freshness while maintaining system stability through structured update procedures.
Solution Approach 2:
The patent employs feedback mechanisms through status bits and control logic that monitor the state of process variables and message buffers. This feedback system ensures that data exchange operations only proceed when conditions are appropriate, preventing inconsistencies during updates while maintaining real-time data availability.
Data Source
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AI summary
The process control unit according to the invention – for example a programmable logic controller or PLC – is configured to execute a plurality of control processes, wherein at least one first control process executed on the process control unit is configured, according to the invention, such that for the execution thereof there is no provision for direct exchange of process variables with a second control process, but rather this exchange takes place via an interposed association module. An association specification is used to ascertain the control process or control processes to which the process variable needs to be handed over. A particular advantage of the invention can be seen in the increased flexibility in the exchange of process variables, which now takes place in the individual control processes by means of an association module as a departure from "logical wiring" frozen by programming. Restarts of the process control unit and associated production losses advantageously become unnecessary. Additional resources in the process control unit or in an engineering system can be reduced or avoided. The decreased complexity means that the control systems and engineering systems are developed more easily and hence also more quickly.