Keep Alive Circuit for Industrial Output Module Failsafe
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Industrial process control systems face challenges in achieving flexible fault tolerance and ensuring fail-safe operations, particularly in systems where full redundancy is not required, leading to high implementation costs and potential disruptions during module changes.
Innovation Solution
An output module comprising a channel failsafe switch, a keep alive circuit, and a driver circuit that generates a drive signal based on a command signal and a drive enable signal, ensuring continuous operation by maintaining a keep alive signal, even in the absence of an alternating current signal, using a charge pump and operational amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Triple Modular Redundancy (TMR) is implemented to provide fault tolerance, then system reliability is improved, but system cost and complexity increase significantly
Solution Approach 1:
The patent applies partial redundancy by implementing a keep-alive circuit that monitors only the critical signal path rather than full TMR triplication. The driver circuit generates a keep-alive signal that is continuously monitored by the failsafe switch, providing selective fault coverage for the most critical functions while avoiding the cost and complexity of complete system triplication.
Solution Approach 2:
The patent introduces a keepsafe circuit as an intermediary component between the driver circuit and the failsafe switch. This keepsafe circuit generates a keep-alive signal that mediates the monitoring function, allowing the system to detect faults in the signal path without requiring full redundant triplication of all system components.
2Reliability
If hot-standby modules are used to maintain system operation during failures, then system availability is improved, but system disruption occurs during module changeover
Solution Approach 1:
The patent implements preliminary fault detection by continuously monitoring the keep-alive signal from the driver circuit through the failsafe switch. This continuous monitoring detects faults before they cause system failure, allowing for proactive maintenance and replacement of faulty modules without disrupting system operation, thereby eliminating changeover time losses.
3Reliability
If dedicated hardware test and diagnostic regimens are implemented for fast fault recognition, then fault detection speed is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the essential fault detection function from complex diagnostic regimens by using a simple failsafe switch that monitors the keep-alive signal. This extraction provides fast fault recognition capability while avoiding the complexity and cost of dedicated hardware test equipment and comprehensive diagnostic software.
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
This solution provides flexible fault tolerance and ensures fail-safe operation by maintaining system functionality even in signal failures, reducing costs and minimizing disruptions, while allowing for online replacement of modules without shutting down the system.
Implementation Method 1
an active drive enable signal comprises an alternating current signal and in which the shutdown circuit comprises a charge pump
Implementation Method 2
the driver circuit comprises an operational amplifier in which the shutdown signal is received by a shutdown pin in said operational amplifier
Data Source
AI summary
An output module for an Industrial Process Control System that drives a load in a failsafe manner. The output module drives a load in response to a driving signal and includes a controller that generates a command signal and a drive enable signal in response to said driving signal. A keep alive circuit generates an active keep alive signal unless the drive enable signal is inactive. The output module includes a driver circuit that generates a drive signal in accordance with the command signal when the keep alive signal is active such that the load can be driven with a channel failsafe switch in response to the drive signal. The output module can be integrated into any of a number of industrial process control systems to enhance the operability of such systems.