Sandboxed PLC Execution Environments for Reliable Expansion
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Solution Overview
Problem
Existing programmable logic controllers (PLCs) in industrial plants face challenges in adapting to hardware changes, limiting the ability to replace or expand PLCs without significant software modifications, and struggle with ensuring error-free execution of control software due to dependencies on other programs running simultaneously.
Innovation Solution
A programmable logic controller with an operating system that includes a higher-level management system with a resource manager, allowing each execution environment to run in a sandbox with independent resource allocation, ensuring trouble-free execution and enabling additive expansion and function addition without impairing existing functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control software is programmed close to the hardware platform with precise matching, then execution reliability is improved, but adaptability to hardware changes deteriorates
Solution Approach 1:
The system segments the control software into multiple independent execution environments (sandboxes) that run on the same hardware platform. Each sandbox contains a complete execution environment with its own control software instance, allowing independent operation and isolation. This enables hardware changes in one sandbox without affecting others, resolving the contradiction between execution reliability and adaptability to hardware changes.
Solution Approach 2:
The hardware platform is designed with universal interfaces and abstraction layers that allow multiple different execution environments to run simultaneously on the same physical hardware. The platform provides standardized communication resources and I/O interfaces that can be allocated to different sandboxes, enabling the system to adapt to various hardware configurations while maintaining reliable control execution in each isolated environment.
2Adaptability or versatility
If additional PLCs are added to expand functionality, then functional versatility is improved, but device complexity and space requirements deteriorate
Solution Approach 1:
Multiple execution environments that would traditionally require separate PLC units are merged into a single PLC hardware platform. The system combines multiple sandboxes, each capable of running independent control software, within one physical controller. This reduces the number of discrete devices needed while maintaining functional versatility through virtualization and resource sharing.
Solution Approach 2:
The system implements a nested structure where multiple execution environments (sandboxes) are contained within a single PLC platform. Each sandbox is further nested with its own execution environment, control software, and allocated resources. This hierarchical nesting allows multiple functional units to coexist in one device, reducing overall system complexity while preserving adaptability.
3Adaptability or versatility
If multiple control programs run simultaneously on one PLC, then functional expansion is improved, but execution reliability deteriorates due to mutual interference
Solution Approach 1:
The system implements preemptive isolation measures by creating sandboxed execution environments before any control programs run. Each sandbox is pre-configured with dedicated resource allocations and isolation boundaries that prevent mutual interference. This beforehand cushioning ensures that even when multiple control programs run simultaneously, they cannot negatively affect each other's execution, maintaining reliability while enabling functional expansion.
Solution Approach 2:
The system introduces an intermediary management layer between multiple control programs and the hardware platform. This intermediary resource manager allocates and mediates access to communication resources, I/O interfaces, and processing power for each sandbox. The intermediary ensures fair and controlled resource distribution, preventing resource conflicts and ensuring reliable execution of multiple simultaneous control programs.
4Adaptability or versatility
If PLC hardware is oversized for current needs, then future expansion capability is improved, but resource utilization efficiency deteriorates
Solution Approach 1:
The system implements dynamic resource allocation where the hardware platform can flexibly allocate resources to different sandboxes based on current needs. The resource manager can dynamically adjust the number and capacity of execution environments running on the platform, allowing the system to scale from using a fraction of available resources to utilizing full capacity as expansion needs arise. This dynamic adaptability resolves the contradiction between oversizing for future capability and efficiency for current usage.
Data Source
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AI summary
Programmable logic controller (1) for at least one field device (101) in an industrial plant (100), comprising a hardware platform (2) on which an operating system (3) runs, the operating system (3) being designed to have at least one execution environment (51 -53), within which control software (61-63) containing the control logic of the programmable logic controller (1) can run, in at least one process, a higher-level management system (4) being provided which is designed to run directly on the operating system (3) to run and execute one or more execution environments (51-53), each in its own sandbox (41-43), the management system (4) comprising a resource manager (44) which is designed to assign each sandbox (41 -43) to allocate access to main memory (21), processor power (22) and communication resources (23) of the hardware platform (2). Associated computer program product.