Safety Gateway State Control for Faster Response on Delayed Networks
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Solution Overview
Problem
Existing safety control systems face challenges in shortening safety response time due to large transmission delays in communication paths, especially in configurations with low punctuality networks or across public networks, where techniques like Patent Literature 1 do not effectively address communication delays.
Innovation Solution
A gateway device is introduced to relay communication between safety input/output units and controllers, featuring a state monitoring control section to manage control states and a safety control section that generates safety data for state transitions, thereby reducing the time for safety data to reach the input/output units and shortening safety response time at a relatively low cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If safety data is transmitted directly from safety input/output units to safety controller through communication path, then communication reliability is maintained, but transmission delay increases safety response time
Solution Approach 1:
The patent introduces a gateway device as an intermediary component between safety input/output units and safety controllers. The gateway receives safety data from input/output units, performs safety determination processing locally, and transmits only determination results to the controller. This intermediary role reduces transmission delay and safety response time while maintaining communication reliability through buffered data transmission.
2Loss of time
If gateway device performs safety determination processing locally, then safety response time is shortened, but device complexity increases
Solution Approach 1:
The patent segments the safety control system into distinct functional modules: safety data reception unit, safety determination unit, and result transmission unit. The gateway device incorporates safety determination means that divides safety determination processing into manageable segments, reducing overall device complexity while achieving faster safety response times through localized processing.
3Reliability
If all safety information is transmitted to safety controller, then communication reliability is ensured, but communication cycle time increases with number of safety slaves
Solution Approach 1:
The patent extracts the safety determination processing function from the central safety controller and places it in the gateway device. Instead of transmitting all raw safety information from multiple safety slaves to the controller, the gateway extracts only the essential determination results. This extraction approach maintains communication reliability while significantly reducing communication cycle time, especially as the number of safety slaves increases.
Data Source
AI summary
A gateway device (10) relays communication of safety data between a safety input/output unit (40) and a safety controller (20) that controls the safety input/output unit (40), and includes a state monitoring control section (130) and a safety control section (120). The state monitoring control section (130) manages a control state that is a state corresponding to a state of the safety control system (80) and is one of a safety state and a non-safety state, and controls a state transition of the control state by applying safety data that the gateway device (10) has received from the safety input/output unit (40) to state transition information that indicates a state transition concerning the control state. When the control state has transitioned from the non-safety state to the safety state, the safety control section (120) generates safety data that indicates the safety state and is to be transmitted to the safety input/output unit (40).