Programmable Controller Web Services for Load-Dependent Data Access
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Solution Overview
Problem
Conventional methods for accessing data or functions of a programmable controller via network protocols, such as web servers and OPC-UA, lead to unnecessary load and rigidity in data exchange, making controlled function calling and flexible access challenging due to direct access limitations and cycle-oriented data exchange issues.
Innovation Solution
Implementing selected program modules of the automation program as web services that can call external applications via HTTP, with an administration instance managing workload-dependent processing, allowing controlled access to internal values, parameters, and functions, and enabling asynchronous execution of program modules without disrupting the automation program's cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a web server is integrated into the programmable controller to enable network access, then data accessibility via network protocols is improved, but the controller generates permanent load and experiences delayed data exchange due to cycle-oriented execution
Solution Approach 1:
The patent segments the web server functionality from the main automation program cycle by introducing a separate event-driven processing mechanism. Network requests are handled as asynchronous events that can be processed independently of the cyclic automation program, allowing data access without permanently loading the controller's main execution cycle.
Solution Approach 2:
The patent introduces an intermediary event queue and message buffer between the web server and the automation program. Network requests are placed in the event queue and processed by the event-driven mechanism, which mediates between external network access and internal program execution, eliminating direct coupling and permanent load.
2Adaptability or versatility
If a control data module and WWW module are defined for data exchange, then network access is enabled, but the architecture becomes complex and rigidly connected to the automation program cycle
Solution Approach 1:
The patent makes the event-driven mechanism a universal handling system that processes multiple types of events (network requests, internal triggers, external interrupts) through a single standardized interface. This eliminates the need for separate specialized modules for each function, reducing architectural complexity while maintaining versatility.
Solution Approach 2:
The patent merges the web server functionality with the existing event-driven architecture of the programmable controller. Instead of maintaining separate control data modules and WWW modules, the solution integrates network request handling into the unified event processing mechanism, simplifying the overall architecture.
3Reliability
If data exchange is rigidly connected to the automation program execution cycle, then data access is controlled, but flexible function calling is not possible and delays occur
Solution Approach 1:
The patent implements a dynamic event processing system where the handling of network requests adapts based on the current controller state and event priority. High-priority events can trigger immediate program module execution, while lower-priority events are queued for processing during idle cycles, providing both control and flexibility.
Solution Approach 2:
The patent maintains periodic execution of the automation program cycle while superimposing asynchronous event processing. The event-driven mechanism checks for pending events at defined intervals and processes them appropriately, ensuring that critical periodic control functions are maintained while allowing flexible response to network requests.
Data Source
AI summary
A method and a programmable controller for accessing data or functions, the data being stored in a database of the programmable controller and the database being assigned to an application program of the programmable controller, and a web server of the programmable controller being accessed by a client via the network protocol, where at least one program module of the automation program of the programmable controller is assigned to a web service of the web server, and where execution of the program module is initiated by the web service such that flexible and simply implementable access to data or functions of the programmable controller is therefore possible, and the access to the data or functions can be controlled load-dependently.