Virtualized PLC Architecture for Hard Real-Time and Flexible Control

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Solution Overview

Problem

Existing programmable logic controllers (PLCs) lack flexibility and cost-effectiveness in managing control programs for automated systems, particularly in environments requiring hard real-time capabilities and non-real-time tasks, limiting the scalability and efficiency of resource utilization.

Innovation Solution

A programmable controller system with a dual execution environment architecture, where a first execution environment meets hard real-time requirements and is hardware-dependent, while a second execution environment is virtualized, allowing for flexible deployment of control programs via a virtualization platform, such as hypervisors or containers, enabling data exchange through network interfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single execution environment is used in traditional PLCs, then hard real-time capabilities are maintained, but flexibility and scalability are limited

Engineering Contradiction:

ImproveflexibilityVSAvoidexecution environment structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system divides the execution environment into two distinct segments: a first execution environment for hard real-time control programs and a second execution environment for flexible control programs. This segmentation allows each environment to be optimized for its specific purpose while coexisting within the same PLC hardware platform.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A communication interface acts as an intermediary between the first and second execution environments, enabling data exchange while maintaining isolation. This mediator allows the flexible second environment to interact with the real-time first environment without compromising the hard real-time guarantees of the latter.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If multiple control programs are run in the same execution environment, then resource utilization improves, but real-time performance may be compromised

Engineering Contradiction:

Improveresource utilizationVSAvoidreal-time performance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system segments the execution environment to separate real-time and non-real-time control programs into different isolated environments. This allows multiple programs to run simultaneously with improved resource utilization while the first execution environment maintains guaranteed real-time performance for time-critical tasks.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different quality levels are assigned to different execution environments: the first execution environment provides hard real-time guarantees for time-critical control functions, while the second execution environment provides flexibility for non-time-critical functions. Each environment has its own resource allocation and scheduling characteristics optimized for its specific requirements.

Inventive Principle:

Principle #3Local quality

3Reliability

If control programs are hardware-dependent, then real-time performance is ensured, but portability and ease of migration are reduced

Engineering Contradiction:

Improvereal-time performanceVSAvoidprogram migration

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The second execution environment uses virtualization technology to create virtual hardware interfaces that replicate the appearance and behavior of physical hardware. This allows control programs to be copied and migrated between different PLC platforms without modification, as they interact with standardized virtual interfaces rather than hardware-specific details.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

Virtualization layers act as intermediaries between the control programs and the physical hardware platform. These intermediaries abstract the hardware dependencies, allowing programs to run on different hardware while maintaining the same interface and behavior, thus enabling easy migration while preserving real-time performance guarantees.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP4685591A1Programmable controller and method for controlling an automated system

Publication Date: 2026.01.28 PILZ GMBH & CO KG

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AI summary

A programmable logic controller (PLC) for controlling an automated system, in which a large number of control devices are interconnected via a communication network (50), has a first hardware platform (60) on which a first operating system (62), dependent on the hardware platform (60), is installed. The first operating system provides a real-time capable first execution environment (64) for a first control program (66). The PLC also has a virtualization platform (68a) that provides a second execution environment (70) for a second control program (72a). A first control program (66) is executable in the first execution environment (70) and implements a first control functionality with hard real-time requirements. A second control program (72a) is executable in the second execution environment (70) and implements a second control functionality.The first execution environment (60) has access to a first network interface (82, 84). The second execution environment (70) provides a second network interface (82). The first control program (66) and the second control program (72a) exchange data with each other via the first and second network interfaces (82).