Raspberry Pi Open Source PLC Communication Wonder LECPython, and Example of Communication with Omron PLC

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Introduction

LECPython is a powerful Python component developed in C# that enables efficient communication between Python and PLCs. This article will guide you on how to install and use the LECPython component on a Raspberry Pi, facilitating your industrial automation projects.

LECPython aims to solve the challenges of establishing efficient communication with programmable logic controllers (PLCs) on embedded devices like the Raspberry Pi. Currently, there is a lack of a complete control component designed specifically for the Raspberry Pi that can quickly and stably achieve communication with various PLCs. This limits the application and development of Raspberry Pi in industrial automation, intelligent manufacturing, and other fields, requiring developers to spend a lot of time and effort writing and optimizing communication code, increasing development difficulty and cost.

Traditional PLC communication solutions rely on PCs or dedicated controllers, which are not advantageous in terms of cost, size, and power consumption. The Raspberry Pi, with its small size, low power consumption, and high cost-performance ratio, has become an ideal choice for the development of IoT and embedded systems. However, the lack of a dedicated PLC communication component limits the potential of the Raspberry Pi in a broader range of industrial applications.

LECPython achieves seamless communication between Python and PLC through a Python component developed in C#, specifically optimized for efficiency and stability on Linux environments like the Raspberry Pi. It supports various popular PLC protocols, such as Modbus, Mitsubishi, Siemens, Omron, etc., meeting the needs of different projects. LECPython's runtime depends on .NET 8, which can automatically detect and install the required runtime environment, simplifying the installation and configuration process and greatly enhancing the developer's experience.

With LECPython, developers can quickly set up a communication system with PLCs on a Raspberry Pi, achieving real-time data acquisition and control, promoting the rapid development and deployment of industrial automation projects. At the same time, LECPython's efficient reading and writing capabilities and stable connection mechanism ensure the reliability of communication and the accuracy of data, providing solid technical support for industrial applications.

Environmental Requirements

Before you begin, please ensure that your Raspberry Pi meets the following requirements:

• Operating System: Raspbian OS (the latest version is recommended)
• Python: Python 3.6 or higher version installed
• .NET 8: LECPython relies on the .NET 8 runtime support, LECPython can automatically install the .NET 8 runtime, no manual installation is required
• Network Connection: Used for automatic downloading and installation of necessary components

Installation Steps

1. Install Python

If Python is not yet installed, you can use the following commands to install it:

sudo apt update
sudo apt install python3 python3-pip

Verify the installation:

python3 --version
pip3 --version

2. Install LECPython

Use pip to install LECPython:

pip3 install LECPython

LECPython will automatically install the required pythonnet dependencies. If necessary, you can also install it manually:

pip3 install pythonnet==3.0.4

Usage Example

The following is a simple example showing how to use LECPython on a Raspberry Pi to connect to an Omron FINS PLC and perform read and write operations.

from LECPython import LECPython

if __name__ == "__main__":
    lecp = LECPython()
    try:
        # Establish a connection with the Omron FINS PLC
        result = lecp.OmronFinsNetConnection("192.168.31.64", 9600, 13, 0, "CDAB", True, 2000)
        print("Omron FINS PLC connection call successful:", result["ErrorCode"])

        # Read 10 floating-point values from address D100
        rtval = lecp.ReadNodeValues(result["Content"], "D100", "float", 10)
        print(f"The read values are: {rtval}")

        # Write floating-point values to address D100
        rtval = lecp.WriteNodeValues(result["Content"], "D100", "float", [88.123, 726.1223])
        print(f"The written values are: {rtval}")

        # Read 10 floating-point values from address D100 again
        rtval = lecp.ReadNodeValues(result["Content"], "D100", "float", 10)
        print(f"The read values are: {rtval}")

        # Close the connection
        lecp.ConnectClose(result["Content"])
    except AttributeError as e:
        print(e)

Running the Example

Save the above code as example.py, then run it in the terminal:

python3 example.py

You should see output similar to the following, indicating a successful connection and completion of read/write operations:

Omron FINS PLC connection call successful: 0
The read values are: {'ErrorCode': 0, 'IsSuccess': True, 'Message': 'Success', 'Content': [88.123, 726.1223, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]}
The written values are: {'IsSuccess': True}
The read values are: {'ErrorCode': 0, 'IsSuccess': True, 'Message': 'Success', 'Content': [88.123, 726.1223, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]}

Common Problems

1. .NET 8 Automatic Installation Failure

If LECPython fails to automatically install .NET 8, please follow the steps for Installing the .NET 8 Runtime to install it manually.

2. Unable to Connect to PLC

• Check Network Configuration: Ensure that the Raspberry Pi and PLC are on the same network and that the IP addresses are configured correctly.
• Verify PLC Settings: Confirm that the communication parameters of the PLC (such as port, network number, etc.) are consistent with the settings in the code.
• Firewall Settings: Ensure that the firewall between the Raspberry Pi and PLC does not block the relevant ports.

3. Failure to Install Dependencies

If you encounter problems when installing pythonnet, try upgrading pip:

pip3 install --upgrade pip
pip3 install pythonnet==3.0.4

Conclusion

With the guidance of this article, you have successfully installed and configured the LECPython component on the Raspberry Pi and achieved basic communication with the Omron FINS PLC. LECPython provides a concise and efficient API, making industrial automation control on embedded devices like the Raspberry Pi easier. Hopefully, this guide will be helpful for your project!