Python OPC DA Server

1. Introduction

OPC (OLE for Process Control) is a standard for communication between devices and software applications in industrial automation systems. OPC DA (Data Access) is a specification that allows real-time data exchange between OPC servers and clients.

In this article, we will explore how to create an OPC DA server using Python. We will cover the basic concepts of OPC DA, the installation of required libraries, and provide a code example to demonstrate the implementation.

2. Installation

To create a Python OPC DA server, we need to install the following libraries:

  1. pywin32: This library provides access to the Windows COM API, which is required for interacting with OPC servers.
  2. pyOPC: This library provides a high-level interface for implementing OPC clients and servers.

To install these libraries, run the following command in your terminal:

pip install pywin32 pyOPC

3. Code Example

The following code demonstrates how to create a simple OPC DA server using Python:

import pythoncom
from pyOPC.server import OPCServer

class MyOPCServer(OPCServer):
    def OPCQuery(self, query):
        # Implement the OPC DA server logic here
        return []

if __name__ == '__main__':
    pythoncom.CoInitialize()
    server = MyOPCServer()
    server.Run()

In this code example, we create a class MyOPCServer that inherits from OPCServer provided by the pyOPC library. We override the OPCQuery method to implement our server logic.

Inside the OPCQuery method, you can perform any custom logic to handle client requests and return data. The method receives a query parameter that contains information about the client's request. In this example, we simply return an empty list as the server does not have any data to provide.

To start the OPC DA server, we initialize the COM environment with pythoncom.CoInitialize() and create an instance of our server class. Finally, we call the Run method to start the server.

4. Conclusion

Creating an OPC DA server using Python is a straightforward process with the help of libraries like pywin32 and pyOPC. In this article, we covered the basics of OPC DA, the installation of required libraries, and provided a code example to demonstrate the implementation.

With the knowledge gained from this article, you can now start developing your own OPC DA servers using Python for industrial automation systems. Keep exploring the possibilities of OPC and Python to enhance your automation solutions.

Table of Contents

  1. Introduction
  2. Installation
  3. Code Example
  4. Conclusion

Note: The code provided in this article is a simple template to get started with OPC DA server development. It needs to be customized according to the specific requirements of your application.