Safety Input Termination Board for Industrial Controllers
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Solution Overview
Problem
Industrial safety control systems face increased complexity and cost due to redundant wiring and custom software requirements for monitoring input modules, which are necessary for achieving Safety Integrity Level (SIL) ratings, but these solutions add complexity and expense without ensuring improved reliability.
Innovation Solution
A termination board that simplifies wiring between input modules and remote devices by combining two standard input modules into a safety input module, using a relay to test module operation and split input signals to both modules, allowing standard modules to be used in safety control systems, reducing installation time and startup costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant wiring and custom software are used to monitor input modules for SIL ratings, then safety integrity level is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines two standard input modules into a single safety input module with integrated redundancy. The termination board merges multiple input channels and combines their signals, eliminating the need for separate redundant wiring while maintaining SIL2 safety requirements through integrated monitoring and signal combination logic.
Solution Approach 2:
The safety input module serves multiple functions: it accepts standard input signals, provides redundant monitoring, performs safety evaluation, and outputs safety-rated signals. This multi-functional design replaces the need for separate custom software and redundant wiring solutions, reducing complexity while maintaining safety integrity.
2Reliability
If redundant wiring and custom software are used to monitor input modules, then safety integrity level is improved, but installation time and startup costs increase
Solution Approach 1:
The safety input module is pre-configured with integrated redundancy and monitoring capabilities during manufacturing. The termination board is pre-wired with combined input channels and monitoring circuitry, eliminating the need for complex field installation and custom software configuration, thus reducing installation time and startup costs.
Solution Approach 2:
The integrated safety input module performs self-monitoring and self-diagnosis of its redundant channels through built-in monitoring circuitry. This self-service capability eliminates the need for external custom software to monitor input modules, reducing installation complexity and startup time.
3Device complexity
If standard input modules are used without integration, then device complexity is reduced, but safety monitoring capability is insufficient for SIL requirements
Solution Approach 1:
The patent merges two standard input modules into a single integrated safety input module. The termination board combines the input channels and integrates monitoring circuitry that evaluates both channels simultaneously, providing SIL2 safety monitoring capability while maintaining the simplicity of standard modules.
Solution Approach 2:
The termination board acts as an intermediary between standard input modules and the safety system. It provides the necessary safety monitoring and signal combination functionality, enabling standard modules to be used in safety-critical applications without requiring custom software or complex wiring.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces wiring complexity and installation time while ensuring SIL2 safety requirements are met, improving reliability without the need for custom software or modules, allowing for fail-safe or fault-tolerant operation.
Implementation Method 1
A relay is mounted on the circuit board and has an input terminal connected to the DC voltage and an output terminal connected to the field supply connector. The relay also has a coil connected to a signal from an output module to selectively enable and disable the relay contact to supply the DC voltage to the field supply connector.
Data Source
Figure 1~3
Figure 4
AI summary
An input termination board for use with an industrial controller in a safety system is disclosed herein. The industrial controller may be populated with standard input modules according to the application. The termination board, in conjunction with the controller allows the standard input modules to be used as safety inputs. The termination board provides simplified wiring between the input modules and the remote devices by splitting each of the signals generated by the remote device into separate inputs for two different input modules. In addition, a program executing on the controller of the safety system monitors and tests each of the inputs in both input modules to verify proper operation of the inputs. If the program detects a fault in either input module, the safety system may alternately shut down according to a fail-safe procedure or continue operating under a fault-tolerant mode of operation.