Asynchronous Master-Slave Automation Failover
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Solution Overview
Problem
Existing high-availability automation systems face challenges in minimizing downtime and avoiding disruptive switchover effects when one subsystem fails, due to the need for synchronous communication between master and slave subsystems, which can lead to long waiting times and inefficiencies.
Innovation Solution
Implementing a method for asynchronous communication between the master and slave subsystems, allowing the master to process ahead or behind the slave without waiting for responses, decoupling processing power from communication bandwidth and enabling event-synchronous processing without a separate synchronization connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If synchronous communication is used between master and slave subsystems to ensure identical system state, then reliability of failover is improved, but loss of time increases due to waiting for responses
Solution Approach 1:
The communication protocol is segmented into essential synchronization data (process images, I/O states) and non-essential administrative data (acknowledgments, status confirmations). Only essential data requires synchronous exchange, while non-essential data can be transmitted asynchronously, reducing waiting time while maintaining failover reliability.
Solution Approach 2:
The master subsystem prepares and transmits synchronization data to the slave in advance, before a failover event occurs. This preliminary synchronization ensures that when failover is needed, the slave subsystem already possesses the necessary system state information, eliminating the need for time-consuming response waiting during critical failover moments.
2Reliability
If synchronous communication is used to maintain identical system state, then reliability of failover is improved, but device complexity increases due to separate synchronization connection
Solution Approach 1:
The synchronization communication and the control data communication are merged into a single communication interface or protocol. The same communication channel used for exchanging control commands and process data also carries synchronization information, eliminating the need for a separate dedicated synchronization connection and reducing overall system complexity.
Solution Approach 2:
The communication interface is designed to serve multiple functions simultaneously: it transmits control commands, process data, and synchronization information all through the same channel. This multi-functional approach eliminates the need for separate dedicated synchronization hardware or protocols, reducing device complexity while maintaining reliable failover capability.
3Reliability
If processing power is coupled with communication bandwidth in synchronous systems, then reliability is improved, but productivity decreases due to communication bottlenecks
Solution Approach 1:
Data transmission is segmented into time-critical synchronization information and non-time-critical administrative information. Only the essential synchronization data requires coordinated timing between master and slave, while administrative data can be processed and transmitted independently, allowing the master subsystem to maintain high processing throughput without being blocked by communication bandwidth limitations.
Solution Approach 2:
Critical synchronization data is prepared and transmitted in advance during normal operation, building a buffer of synchronized information. When the master subsystem has high processing load, the slave can continue to operate using previously synchronized data, allowing the master to process at full speed without being constrained by real-time communication bandwidth requirements.
Data Source
AI summary
The method involves controlling the operation of master (M) and slave (S) by a control program. The slave is configured to perform the function of the master in an event (E), when master fails. The processing sections (Va) of the program is processed by the master. The predetermined time interval of event to the slave is a current release (F1-F4) by the master is transmitted. The processing sections of the control program (P1) is processed by the master due to the current release processing sections of the control program (P2) processed by the slave. An independent claim is included for a redundant automation system.