Safety Controller Network Segmentation for Flexible Expansion
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Solution Overview
Problem
Existing safety controller systems are inflexible and require extensive reprogramming and expert knowledge to adapt to changes in the system structure, such as adding or removing safety controllers, which limits their scalability and efficiency due to the need for centralized coordination and reserved data areas in the process image.
Innovation Solution
A safety controller network design where each safety controller operates independently, sharing a common global process image and communicating point-to-point, allowing for flexible reconfiguration without requiring expert knowledge, and using a single bit range for safety functions, enabling modular expansion without increasing the process image width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If safety controllers are connected in a network with centralized coordination and reserved data areas, then system structure is stable, but system flexibility and adaptability to changes deteriorate
Solution Approach 1:
The system is segmented into independent safety controllers that each manage their own data areas locally. Instead of a centralized process image, each controller has autonomous control over its safety functions and communicates only necessary information to neighbors. This segmentation allows individual controllers to be added, removed, or modified without affecting the entire system structure, thus improving adaptability while maintaining stability through standardized communication protocols.
Solution Approach 2:
The system transitions from a static centralized architecture to a dynamic distributed architecture where controllers can be dynamically added or removed from the network. The communication protocol automatically adapts to changes in network topology, allowing the system to dynamically reconfigure itself without requiring centralized reprogramming or validation, thereby enabling flexible system changes while maintaining structural stability.
2Adaptability or versatility
If additional safety controllers are added to the network, then system functionality is expanded, but process image width increases
Solution Approach 1:
The process image is segmented into local data areas at each safety controller rather than being a single centralized structure. Each controller manages its own data area independently, so adding more controllers increases the number of local data areas but does not increase the width of any individual process image. This segmentation allows system expansion without consuming additional process image width resources at any single point.
Solution Approach 2:
The system transitions from a one-dimensional centralized process image to a multi-dimensional distributed data structure where data is organized across multiple controllers in the network. Each controller maintains its own data area, and the overall system capacity scales by adding more controllers rather than expanding the width of a single process image, effectively moving the scaling dimension from width to network size.
3Ease of operation
If system changes are made without reprogramming, then ease of operation improves, but safety reliability may deteriorate
Solution Approach 1:
The safety controllers perform self-validation and self-configuration when added to or removed from the network. Each controller autonomously validates its own safety functions and communicates its status to neighbors, eliminating the need for external expert reprogramming while maintaining safety reliability through built-in validation mechanisms. The system self-adjusts to changes in network topology without compromising safety integrity.
Solution Approach 2:
The system implements continuous feedback mechanisms where safety controllers communicate their operational status and safety function validity to neighboring controllers. When system changes occur, the feedback loop automatically validates the changes and ensures safety requirements are met before allowing operation, thus enabling easy reconfiguration while maintaining reliability through automated safety validation.
Data Source
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AI summary
The controller has an input terminal connected to a sensor and an output terminal connected to an actuator. A communication interface exchanges control relevant information. A control unit is arranged to carry out a control program, which generates a control signal at the output terminal. The control program comprises logic rules to receive the exchangeable control relevant information from another set of safety controllers (10a-10c) and provide result of the processing at the communication interface for a point to point communication at the safety controllers. An independent claim is also included for a method for setting-up or changing a line arrangement of safety controllers.