How Edge Computers Running Linux Can Become Reliable Real-Time SoftPLCs/vPLCs

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Edge computing is revolutionizing industrial automation by enabling Linux-based systems to function as SoftPLCs (Software Programmable Logic Controllers) or vPLCs (Virtual PLCs). This approach leverages the power of open-source tools like Snap7, a widely adopted project in industrial automation, developed by Davide Nardella.

You Should Know:

1. Why Use Linux for Real-Time PLCs?

Linux provides a flexible, scalable, and cost-effective platform for industrial automation. With real-time kernel patches (PREEMPT_RT) and optimized scheduling, Linux can achieve deterministic performance required for PLC operations.

2. Key Tools & Libraries

  • Snap7 (GitHub) – A powerful open-source library for Siemens S7 communication.
  • CODESYS – A runtime environment for PLC programming on Linux.
  • Eclipse 4diac – An open-source framework for industrial automation.

3. Setting Up a Real-Time Linux Kernel

To ensure low-latency performance, apply the PREEMPT_RT patch:

 Download the kernel source 
wget https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.15.tar.xz 
tar -xf linux-5.15.tar.xz 
cd linux-5.15

Apply PREEMPT_RT patch 
wget https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.15/patch-5.15-rt.patch.xz 
unxz patch-5.15-rt.patch.xz 
patch -p1 < patch-5.15-rt.patch

Configure and compile 
make menuconfig  Enable CONFIG_PREEMPT_RT 
make -j$(nproc) 
sudo make modules_install install

4. Running Snap7 for PLC Communication

Install and configure Snap7 for S7 protocol communication:

 Clone Snap7 
git clone https://github.com/davenarde/Snap7.git 
cd Snap7/build/unix 
make -f x86_64_linux.mk 
sudo cp ../bin/x86_64-linux/libsnap7.so /usr/lib/

5. Testing Real-Time Performance

Use cyclictest to verify real-time capabilities:

sudo apt-get install rt-tests 
cyclictest -t1 -p80 -n -i 10000 -l 10000

6. Integrating with Industrial Protocols

  • Modbus (libmodbus) 
    sudo apt-get install libmodbus-dev
  • OPC UA (open62541) 
    git clone https://github.com/open62541/open62541.git 
cd open62541 
mkdir build && cd build 
cmake .. 
make 
sudo make install

What Undercode Say

Linux is transforming industrial automation by replacing traditional PLCs with software-driven, real-time solutions. Open-source tools like Snap7, CODESYS, and PREEMPT_RT make it possible to deploy high-performance, low-cost automation systems.

Expected Output:

  • A deterministic Linux-based SoftPLC with < 50µs latency.
  • Seamless integration with Siemens S7, Modbus, and OPC UA.
  • Reduced hardware dependency using virtualized PLCs.

Prediction

The adoption of Linux-based PLCs will grow rapidly, driven by edge computing, AI-driven automation, and open-source industrial stacks. Expect more real-time optimizations and containerized PLC deployments in the next 5 years.

References:

Reported By: UgcPost 7329910375796166656 – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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