ESP32-PLC is an open-source project that enables the ESP32 microcontroller to function as a Programmable Logic Controller (PLC) using ladder logic programming. Built with the Espressif IoT Development Framework (ESP-IDF), it leverages the ladderlib C library to execute ladder logic programs and likely integrates with the ladder-editor web application for designing control logic. This project is currently under active development, offering a cost-effective solution for industrial automation, educational purposes, and hobbyist projects.
- Introduction
- Features
- System Architecture
- Hardware Requirements
- Software Requirements
- Installation
- Usage
- Example Applications
- Troubleshooting
- Contributing
- License
The ESP32-PLC project, developed by hiperiondev, aims to transform the ESP32 microcontroller into a Programmable Logic Controller (PLC) for industrial automation and control systems. PLCs are specialized devices used to control machinery and processes through programmed logic, commonly using ladder logic, a graphical programming language defined by the IEC 61131-3 standard. Unlike traditional PLCs, which can be expensive, this project leverages the low-cost, feature-rich ESP32, known for its dual-core processor, Wi-Fi, and Bluetooth capabilities, to provide an accessible alternative.
The project uses the Espressif IoT Development Framework (ESP-IDF), a low-level development environment that offers greater control over the ESP32 hardware compared to Arduino-based solutions. It likely integrates the ladderlib C library for executing ladder logic programs and may work with the ladder-editor, a web-based tool for creating and simulating ladder logic diagrams. As a work-in-progress, the project may lack comprehensive documentation, but it holds promise for applications in industrial automation, education, and IoT.
The following features are inferred based on the project’s context and related repositories:
- Ladder Logic Programming: Supports ladder logic, a graphical language resembling electrical relay circuits, using the ladderlib library.
- ESP-IDF Framework: Built with ESP-IDF for low-level control and optimization on the ESP32.
- Hardware Interaction: Interfaces with ESP32 GPIO pins for reading inputs (e.g., sensors) and controlling outputs (e.g., relays).
- Web-Based Editor Support: Likely compatible with the ladder-editor for designing and simulating ladder logic diagrams.
- Potential IoT Integration: May leverage ESP32’s Wi-Fi and Bluetooth for remote monitoring or control (speculative, pending project updates).
- Open-Source: Freely accessible codebase, encouraging community contributions.
Note: As the project is under development, the feature set may evolve. Check the GitHub repository for updates.
The ESP32-PLC project likely employs a modular architecture:
- Ladder Logic Editor:
- Users create ladder logic diagrams using a tool like the ladder-editor, a web-based application that supports real-time communication via WebSockets.
- Diagrams consist of “rails” and “rungs” representing logical operations, such as contacts (inputs), coils (outputs), timers, and counters.
- Program Execution with ladderlib:
- The ladderlib C library provides a framework to define, execute, and manage ladder logic programs.
- It supports 39 instructions, 6 execution states, 8 error codes, and function pointers for hardware I/O, optimized for embedded systems like the ESP32.
- ESP32 Runtime:
- The ESP32 executes the ladder logic program, using ESP-IDF to manage hardware interactions.
- The runtime likely uses FreeRTOS (included in ESP-IDF) for real-time task scheduling.
- Communication Layer (Speculative):
- The ESP32’s Wi-Fi or Bluetooth capabilities may enable communication with external systems, such as IoT platforms or Human-Machine Interfaces (HMIs), though this is not confirmed.
To implement the ESP32-PLC project, you will need:
- ESP32 Development Board: A board like the ESP32-WROOM-32 or ESP32-DevKitC with sufficient GPIO pins (e.g., ESP32 Dev Module).
- Input Devices: Sensors (e.g., push buttons, proximity sensors) or switches for digital/analog inputs.
- Output Devices: Actuators (e.g., relays, motors, LEDs) for digital/analog outputs.
- Power Supply: A stable 5V or 3.3V power source with adequate current (e.g., 2A).
- Connection Hardware: Breadboard, jumper wires, or a custom PCB for connecting components.
Example Hardware Setup:
| Component | Description | Example |
|---|---|---|
| ESP32 Board | Microcontroller for PLC logic | ESP32-WROOM-32 |
| Push Button | Digital input for triggering logic | Tactile switch |
| Relay Module | Output for controlling devices | 5V single-channel relay |
| Power Supply | Power for ESP32 and peripherals | 5V 2A USB power adapter |
- ESP-IDF Framework: Version 5.4.1 or later, available at ESP-IDF Documentation.
- Ladder Logic Editor: The ladder-editor or a compatible tool for creating ladder logic diagrams.
- Development Environment: A code editor like VSCode with the ESP-IDF extension or a command-line interface for building and flashing.
- Optional Tools: Serial monitor (e.g., minicom, PuTTY) for debugging, or MQTT clients for potential IoT integration.
Follow these steps to set up the ESP32-PLC project:
- Install ESP-IDF:
- Follow the ESP-IDF Getting Started Guide to install ESP-IDF on your system (Windows, macOS, or Linux).
- Ensure the ESP-IDF tools (e.g.,
idf.py) are added to your system’s PATH.
- Clone the Repository:
git clone --recurse-submodules https://github.com/hiperiondev/ESP32-PLC.git - Set Up the Project:
- Navigate to the project directory:
cd ESP32-PLC - Configure the project using ESP-IDF’s menuconfig (if required):
idf.py menuconfig - Build the Project:
- Compile the project using the ESP-IDF build system:
idf.py build - Flash to ESP32:
- Connect your ESP32 board via USB.
- Flash the firmware, replacing
PORTwith your serial port (e.g.,/dev/ttyUSB0on Linux orCOM3on Windows):
idf.py -p PORT flash - Monitor Output:
- Use the ESP-IDF monitor to view serial output for debugging:
idf.py monitor The workflow for using the ESP32-PLC project includes:
- Design Ladder Logic:
- Use the ladder-editor web application to create ladder logic diagrams. Test the editor at LADDER-EDITOR.
- Create diagrams with inputs (e.g., buttons), outputs (e.g., relays), and logic elements (e.g., timers, counters).
- Generate Program Data:
- The ladder-editor may generate a data file, code snippet, or configuration that represents the ladder logic program. The exact format is unclear due to the project’s early stage.
- Integrate with ESP32-PLC:
- Include the generated data or code in the ESP32-PLC project, possibly by placing it in a specific directory or modifying the source code.
- Update the project’s configuration to map inputs/outputs to ESP32 GPIO pins.
- Build and Flash:
- Rebuild the project and flash it to the ESP32 as described in the Installation section.
- Run and Monitor:
- Power on the ESP32 and connected hardware.
- Monitor the execution using the ESP-IDF monitor or external tools to verify the ladder logic behavior.
Note: Specific integration steps may depend on the project’s implementation. Refer to the GitHub repository for updates.
The following hypothetical applications illustrate potential uses, based on similar ESP32 PLC projects:
- Relay Control System:
- Objective: Activate a relay when two buttons are pressed simultaneously.
- Ladder Logic: A rung with two normally open contacts in series (AND logic) controlling a coil.
- Hardware: Buttons on GPIO 5 and 6, relay on GPIO 18.
- Timer-Based Automation:
- Objective: Turn on a motor 5 seconds after a sensor detects an object.
- Ladder Logic: A sensor contact triggers a timer (TON), which activates a coil after 5 seconds.
- Hardware: Proximity sensor on GPIO 4, motor driver on GPIO 19.
- Counter-Based Control:
- Objective: Stop a conveyor after detecting 10 items.
- Ladder Logic: A sensor contact increments a counter, triggering an output when the count reaches 10.
- Hardware: Sensor on GPIO 15, relay on GPIO 23.
Common issues and solutions:
-
Build Errors:
-
Issue:
idf.py buildfails due to missing dependencies. -
Solution: Ensure ESP-IDF is correctly installed and the project’s
CMakeLists.txtincludes required components (e.g., ladderlib). -
Flash Failures:
-
Issue:
idf.py flashcannot connect to the ESP32. -
Solution: Verify the serial port, ensure the ESP32 is in bootloader mode (hold BOOT button), and check USB connections.
-
Logic Not Executing:
-
Issue: Outputs do not respond to inputs.
-
Solution: Check GPIO pin assignments in the code, verify hardware connections, and use
idf.py monitorto debug. -
Missing Documentation:
-
Issue: Unclear how to integrate ladder logic programs.
-
Solution: Monitor the GitHub repository for updates or contribute to documentation efforts.
Contributions are welcome, especially given the project’s early stage. To contribute:
- Submit issues or feature requests on the GitHub Issues page.
- Propose code or documentation improvements via pull requests.
- Engage in discussions on the repository to share ideas.
Distributed under the MIT License. See LICENSE.txt for more information.