Controller Replacement via Cache-Server I/O Routing
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Solution Overview
Problem
Existing process control systems require system shutdown for hardware replacement, and they incur excessive communication and processing loads when accessing field devices via networks, limiting flexibility and efficiency in controlling and managing field devices.
Innovation Solution
A control system architecture that includes field devices, access route controllers, and a cache server to distribute processing load and enable seamless access and migration of control applications, allowing for hardware replacement without system shutdown, using a network to route input/output instructions and data through a cache server for load management and optimal access methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If field devices are directly connected to a controller (I/O node architecture), then communication speed and control responsiveness are improved, but system flexibility and hardware replaceability deteriorate
Solution Approach 1:
The system divides the control architecture into separate functional modules: I/O nodes for direct field device connection, controllers for control logic execution, and a cache server for data management. This segmentation allows each component to be independently replaced or upgraded without affecting the entire system, resolving the contradiction between direct connection speed and hardware replaceability.
Solution Approach 2:
The patent introduces a cache server as an intermediary component between controllers and field devices. The cache server manages input/output data and routes requests, enabling controllers to access field device data without direct physical connection. This intermediary layer maintains fast access performance while allowing flexible hardware replacement of controllers.
2Adaptability or versatility
If controller hardware is replaced in a directly-connected architecture, then system adaptability is improved, but system continuity deteriorates due to required shutdown
Solution Approach 1:
The system performs preliminary actions by maintaining a cache of input/output data on the cache server before controller replacement is needed. When a controller fails or needs replacement, the cache server already contains the necessary data, allowing a new controller to be quickly configured and activated without system shutdown, thus maintaining system continuity while enabling hardware replacement.
Solution Approach 2:
The patent implements a mechanism where control applications and their associated data are discarded from the failing controller and recovered from the cache server. The cache server preserves the input/output data independently, allowing it to be recovered and transferred to a replacement controller, ensuring system continuity during hardware replacement.
3Adaptability or versatility
If control applications access field devices via network, then hardware flexibility is improved, but communication load and processing overhead increase
Solution Approach 1:
The system creates copies of field device data by maintaining a cache on the cache server. Controllers access this cached copy rather than directly communicating with field devices over the network for every operation. This copying mechanism reduces network communication load and processing overhead while maintaining the flexibility of network-based access.
Solution Approach 2:
The cache server performs preliminary actions by pre-fetching and caching input/output data from field devices before controllers need them. This preliminary data preparation reduces the frequency and volume of network communications required when controllers access field device data, thereby reducing communication load and energy consumption while maintaining access flexibility.
Data Source
AI summary
A control system includes at least one field device, a first control apparatus, a second control apparatus, a cache server, and a network. The first control apparatus has a first field device directly connected thereto and includes a first access route controller and a first control application capable of controlling the first field device. The second control apparatus includes a second access route controller and a second control application capable of controlling the first field device. The cache server includes a memory and a third access route controller. The first through third access route controllers are configured to work together to be capable of transferring, to the cache server, an input/output instruction for the first field device from the second control application.