PLC Process Image Integration for Virtual Sensor Synchronization
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Solution Overview
Problem
Modern programmable logic controllers lack compatibility between simulation programs and their data structures, leading to inadequate data exchange and consistency, which hampers effective system control and fault prevention.
Innovation Solution
A programmable logic controller with a computing unit that runs both the simulation program and controls the system, utilizing an extended process image in a compatible data format, allowing for seamless data conversion and synchronization through a conversion routine, enabling the integration of virtual sensors for improved operational stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If simulation programs are installed on a separate computing unit, then the programmable logic controller can maintain its existing data structure, but compatibility and data exchange consistency between the simulation program and the PLC deteriorate
Solution Approach 1:
The patent combines the simulation program with the programmable logic controller into a single integrated system. The simulation program is stored in the PLC's memory and executed by the PLC's processor, eliminating the need for separate computing units and external data exchange interfaces. This integration ensures automatic data consistency while simplifying the overall system configuration.
Solution Approach 2:
The programmable logic controller is designed to perform multiple functions: it serves as both the control system and the simulation environment. The PLC can execute both control programs and simulation programs, access both real sensor data and virtual sensor data, and manage both physical and virtual actuators within a single unified platform.
2Speed
If the simulation program accesses the PLC's memory directly, then data exchange speed improves, but data consistency and fall protection deteriorate
Solution Approach 1:
The patent segments memory access into distinct time periods: one period for the PLC's control operations and another period for the simulation program's access. The operating system manages these time segments, allowing the simulation program to access process images and virtual sensor data at high speed during its allocated time while ensuring the PLC's control operations complete without interruption, thus maintaining data consistency.
Solution Approach 2:
The simulation program accesses PLC memory in periodic cycles rather than continuously. The operating system allocates specific time windows for simulation program access, during which it can rapidly read/write data. Between these periods, the PLC maintains its control operations, ensuring data consistency through the periodic synchronization approach.
3Adaptability or versatility
If manual data format conversion is required between process images and simulation data structures, then data exchange flexibility improves, but operational efficiency and productivity deteriorate
Solution Approach 1:
The patent changes the fundamental parameter of data structure organization by using a unified process image data structure that both the PLC and simulation program can access directly. Instead of converting between different data formats, the system allows the simulation program to read and write to the same process image arrays that the PLC uses, eliminating conversion overhead while maintaining full adaptability through the standardized process image format.
4Stability of the object's composition
If virtual sensors are integrated into the process image, then system control stability improves, but memory access complexity increases
Solution Approach 1:
The patent creates virtual sensor data as copies within the process image structure. Virtual sensor values are stored in the same process image arrays as real sensor data, allowing the simulation program to generate virtual sensor readings that are treated identically to physical sensor readings by the control system. This copying approach integrates virtual sensors seamlessly without adding access complexity.
Data Source
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AI summary
In summary, the invention relates to a programmable logic controller (SPS) particularly for controlling a system (A). The programmable logic controller (SPS) is supplemented by a simulation program (13), wherein the simulation program (13) runs on a computing unit (1) if applicable, the programmable logic controller (SPS) and the computing unit (1) communicating via a technical data link (5). Process images (PAsystem, PAAsystem, PAEsystem) are converted in the programmable logic controller (SPS) into extended process images (c-PAext, c-PAAext_i, c-PAEext_i) and are stored in the memory (7) of the programmable logic controller (SPS). The simulation program (13) additionally has access to the memory (7) via the operating system (OS) of the programmable logic controller (SPS) and writes the virtual sensor system (VS) into the memory (7). The virtual sensor system (VS) is advantageously used for adapting a program of the programmable logic controller (SPS) and thus for controlling and/or regulating the system (A).