Automation Server Failover with Reduced-Function Backup Messaging
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Solution Overview
Problem
Existing automation systems with redundant server units are complex and costly, and fail to reliably detect server unit failures, potentially causing damage to the machine if the server unit fails.
Innovation Solution
An automation system with a main and standby server unit that monitors the main server's functionality, activates a failure mode upon detection, and uses a different control program code to ensure the standby server unit can take over with reduced functionality, ensuring high fault tolerance and safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant server unit is implemented to ensure fault tolerance, then the system reliability is improved, but the device complexity and cost increase
Solution Approach 1:
The standby server unit continuously monitors the main server unit's functionality in advance and is pre-configured with the same control program code, enabling it to immediately take over control of the automation system upon detecting a failure event without requiring complex real-time decision-making or reconfiguration
Solution Approach 2:
The standby server unit is designed as an identical copy of the main server unit, running the same control program code and maintaining the same operational state through continuous monitoring of telegram exchanges, allowing for seamless failover without complex synchronization mechanisms
2Productivity
If the server unit failure is not reliably detected, then the system continues operating, but the machine may be damaged
Solution Approach 1:
The standby server unit continuously monitors the functionality of the main server unit by observing telegram exchanges and uses this feedback to detect failure events, ensuring that any malfunction is immediately identified and triggering a safe state transition to prevent machine damage
3Reliability
If a full-function backup server unit is used, then the fault tolerance is improved, but the cost and complexity increase
Solution Approach 1:
The standby server unit is configured to perform only the essential function of monitoring the main server and taking over control upon failure, rather than maintaining all full operational capabilities simultaneously, reducing resource requirements while ensuring adequate fault tolerance through the continuous monitoring and immediate failover mechanism
Data Source
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AI summary
In an automation system, a replacement server unit is designed to receive the normal messages exchanged between a main server unit and a client unit. At the same time, the functional capability of the main server unit is continually monitored. If a failure event of the main server unit is detected, the replacement server unit is designed to activate a failure operating mode; in the failure operating mode, the replacement server unit and the client unit exchange failure messages. In the failure messages, the predefined payload structure of the normal messages is divided into relevant data elements and optional data elements. The replacement server unit is designed to use, for the relevant data elements of the first failure message, the data values of the relevant data elements of the currently available normal message and, for the optional data elements of the first failure message, predefined default data values.