Duplex Process Control Data Sync During Idle Control Cycles
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Solution Overview
Problem
In duplexing process control devices, the existing method of transferring control data from the control system controller to the standby system controller is time-consuming, especially when dealing with large amounts of data, leading to increased control cycle lengths and decreased performance due to insufficient allocation of time for program calculation and process input/output operations.
Innovation Solution
The duplexing process control device includes a control system controller and a standby system controller, where control data accessed during program calculation and process input/output by the CPU is stored in a control data memory, and the addresses and data are transmitted to the standby system controller, allowing the control data to be expanded before program calculation, thereby efficiently transferring and equalizing control data between the two systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control data is transferred from the control system controller to the standby system controller using the existing method, then the control data equalization is achieved, but the transfer time increases and control cycle lengthens
Solution Approach 1:
The patent applies preliminary action by having the standby system controller pre-fetch control data from the control system controller's memory during idle periods before the control cycle completes. This allows the data to be ready for immediate use when needed, eliminating the need to wait for traditional end-of-cycle transfers and thus reducing the impact on control cycle length.
Solution Approach 2:
The patent introduces an intermediary mechanism through a dedicated data transfer interface that operates independently from the main control cycle. This intermediary channel allows control data to be transferred in parallel during idle periods without interfering with the primary control operations, effectively decoupling the transfer time from the control cycle length.
2Reliability
If control data is transferred during the control cycle, then the standby system is kept synchronized, but the time for program calculation and process input/output operations becomes insufficient
Solution Approach 1:
The patent implements periodic action by utilizing idle periods within the control cycle for data transfer operations. Instead of continuous or centralized transfers that would compete for resources, the system performs periodic data synchronization during naturally occurring idle times, thus maintaining standby synchronization without impacting the productivity of program calculation and I/O operations.
Solution Approach 2:
The patent applies dynamics by making the data transfer timing flexible and adaptive to the control cycle's idle periods. The transfer operations are dynamically scheduled based on when resources are available, rather than following a fixed timetable that would constrain program calculation and process I/O performance. This dynamic approach allows the system to maintain synchronization while preserving productivity.
3Reliability
If large amounts of control data are transferred, then complete equalization is achieved, but the transfer process becomes time-consuming
Solution Approach 1:
The patent applies segmentation by dividing the control data transfer into smaller segments that are transferred incrementally during idle periods throughout the control cycle. Instead of transferring all data at once in a single large operation, the data is segmented and transferred in multiple smaller batches, reducing the impact on any single control cycle while achieving complete equalization over time.
Solution Approach 2:
The patent uses preliminary action by starting the transfer of control data segments during idle periods before they are needed. This allows the transfer process to begin early and continue in the background, so that by the time the data is needed for synchronization, much of the transfer is already complete or in progress, reducing the overall time impact.
Data Source
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AI summary
An address and a control data accessed when the CPU (11) performs the program calculation in the control data memory (12) of the control system controller (2) are transmitted to the standby system controller (3), in the standby system controller (3), the control data transmitted from the control system controller (2) to the address transmitted from the control system controller (2) before the program calculation of the CPU (21) of the standby system controller (3) is expanded, the control data equalization of the control system controller (2) and the standby system controller is performed, the control data is efficiently transmitted from the control system controller to the standby system controller (3), thus, the processing performance of the duplexing process control device (1) is improved.