Safety Control Device Segmentation for Reliability
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Solution Overview
Problem
Existing safety-related control devices face challenges in integrating non-safety functions without compromising the deterministic and real-time requirements of safety functions, leading to conflicts and increased complexity as the design becomes more extensive.
Innovation Solution
Implementing safety and non-safety functions on separate processing devices, with the safety function as a deterministic real-time system on one device and non-safety functions, including diagnostics and test functions, on another, allowing for reduced safety requirements for non-safety functions and no additional hardware for the test function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If safety functions and operating functions are integrated on the same processing device, then device complexity is reduced, but reliability of safety function deteriorates due to resource conflicts
Solution Approach 1:
The control device is segmented into two separate processing devices: a first processing device dedicated to safety functions and a second processing device for operating functions. This segmentation prevents resource conflicts between safety-critical and non-safety-critical operations, ensuring that safety functions maintain deterministic real-time performance while operating functions can utilize available resources without compromising safety reliability.
2Reliability
If safety functions and operating functions are separated onto different processing devices, then reliability of safety function is improved, but device complexity increases
Solution Approach 1:
The control device is segmented into two separate processing devices: a first processing device dedicated to safety functions and a second processing device for operating functions. This segmentation prevents resource conflicts between safety-critical and non-safety-critical operations, ensuring that safety functions maintain deterministic real-time performance while operating functions can utilize available resources without compromising safety reliability.
3Reliability
If non-safety functions are implemented with high safety requirements, then safety reliability is improved, but ease of manufacture deteriorates due to increased development complexity
Solution Approach 1:
The control device is segmented into two separate processing devices: a first processing device dedicated to safety functions and a second processing device for operating functions. This segmentation prevents resource conflicts between safety-critical and non-safety-critical operations, ensuring that safety functions maintain deterministic real-time performance while operating functions can utilize available resources without compromising safety reliability.
Solution Approach 2:
Different safety requirement levels are applied locally to different functional areas: the first processing device implementing safety functions adheres to high safety requirements (e.g., DIN EN 61508), while the second processing device implementing operating functions can use standard development processes. This local quality approach allows each subsystem to be developed with appropriate rigor without unnecessarily increasing overall development complexity.
Data Source
AI summary
A safety-related control device for controlling an actuator with a first processing device that is configured to provide a safety function for the generation and/or processing of a signal for a safety-related control of the actuator, and a second processing device that is configured to provide an operating and/or additional function for the generation, processing, diagnostics, reproduction and/or transmission of further signals associated with the operation of the control device and/or of the actuator, and wherein the second processing device is furthermore configured to provide a test function for monitoring the functionality of the safety function.