OpenOPC for Python 1.2.0

Project Description

OpenOPC for Python is a free, open source and easy to use OPC (OLE for Process Control) library designed to be used with the popular Python programming language. The project also includes a Windows gateway service that enable non-Windows clients to also access OPC-DA calls.

The files within this repository allow us to work with recent versions of Python (v3.7+) and Pyro4 (v4.80+).

If you are interested in the original version from Barry Barnreiter, you can go here. However, if you want to try a different fork that also works with Python 3.4+ (if you make some minor changes to the Python source code that affects Pyro4), go to the GitHub version of Anton D. Kachalov by clicking here.

Contents

This repository offers the following files:

• An OpenOPC Gateway Service (a Windows service providing remote access to the OpenOPC library, which is useful to avoid DCOM issues).
• An OpenOPC for Python library module (used to connect to an OPC server from both Windows and Linux).
• A system check module (allows you to check the health of your system for performance, free memory, tasks list, among others).
• A free OPC automation wrapper (required DLL file).
• General documentation with updated procedures (this file).
• Documentation from the original author.

Prerequisites and Considerations

Follow these steps to prepare your work environment:

• Make sure to download and install a recent Python version (v3.7+) in both your remote (i.e. Debian Jessie) and local (i.e. Windows 7) nodes. To do this, go here.
• Make sure to download and install Python for Windows Extensions (pywin32) for a recent Python version (i.e. pywin32-228.win32-py3.7.exe) in your Windows box. To do this, go here.
• Make sure to download and install a recent Pyro4 version (v4.80+) in both your remote (i.e. Debian Jessie) and local (i.e. Windows 7) nodes by typing:

pip install Pyro4 

or

pip install Pyro4==4.80

• Make sure these environment variables in your Windows box are set as shown:

OPC_CLASS=Matrikon.OPC.Automation;Graybox.OPC.DAWrapper;HSCOPC.Automation;RSI.OPCAutomation;OPC.Automation
OPC_CLIENT=OpenOPC
OPC_GATE_HOST=192.168.1.96    # IMPORTANT: Replace with your IP address
OPC_GATE_PORT=7766
OPC_HOST=localhost
OPC_MODE=dcom
OPC_SERVER=Hci.TPNServer;HwHsc.OPCServer;opc.deltav.1;AIM.OPC.1;Yokogawa.ExaopcDAEXQ.1;OSI.DA.1;OPC.PHDServerDA.1;Aspen.Infoplus21_DA.1;National Instruments.OPCLabVIEW;RSLinx OPC Server;KEPware.KEPServerEx.V4;Matrikon.OPC.Simulation;Prosys.OPC.Simulation

• If they are not set, open a command prompt window to do that by typing:

C:\>set ENV_VAR=VALUE
C:\>set OPC_GATE_HOST=172.16.4.22    # this is an example

• Make sure the firewall is allowed to keep the port 7766 open. If in doubt, and you're doing a quick test, just turn off your firewall completely.
• Keep in mind this scheme if you're still have questions about which packages are required and which ones are optional for you to work without issues (remember that Python is necessary on all platforms):

1. Win32 platform, using the OpenOPC Gateway Service

Pywin32:  optional
Pyro4:    required

2. Win32 platform, talking to OPC Servers directly using COM/DCOM

Pywin32:  required
Pyro4:    optional

3. Non-Windows platform (use of Gateway Service is mandatory)

Pywin32:  not applicable
Pyro4:    required

• For easy testing, make sure an OPC server is installed in your Windows box (i.e. Matrikon OPC Simulation Server).
• In order to get the most from the OpenOPC package, Windows developers are encouraged to install both Pywin32 and Pyro4. Using Pyro4 to talk to the Gateway Service provides a quick and easy method for bypassing the DCOM security nightmares which are all too common when using OPC.
• The work environment for testing these changes was a remote Debian Jessie box with a local Windows 7 Ultimate Service Pack 1 32-bit machine (where the Matrikon OPC Simulation Server was installed).

Installation

Getting Started

Begin to work with this project by doing this:

• Clone or download the repository as a .zip file.
• Extract the compressed file to a folder in your Windows box (i.e. C:\OpenOPC37).
• Open a command prompt window (run it as administrator) and go to your work directory (i.e. C:\OpenOPC37).
• Change to the lib folder.
• Register the OPC automation wrapper ( gbda_aut.dll ) by typing this in the command line:

C:\OpenOPC37\lib>regsvr32 gbda_aut.dll

• If, for any reason, you want to uninstall this file and remove it from your system registry later, type this in the command line:

C:\OpenOPC37\lib>regsvr32 gbda_aut.dll -u

Install the OpenOPC Gateway Service

This goal can be achieved by running the "OpenOPCService.py" script with the Python interpreter and the "install" argument (remember to do it as administrator):

• In the command prompt window, go to your work directory (i.e. C:\OpenOPC37).
• Change to the src folder.
• Install the OpenOPC Gateway Service by typing this in the command line:

C:\OpenOPC37\src>python OpenOPCService.py install

• Wait while the following message is shown on the screen:

Installing service zzzOpenOPCService
Service installed

Usage

Start the OpenOPC Gateway Service

This task can be completed from one of two ways (make sure to have it installed first):

• By clicking the Start link on the "OpenOPC Gateway Service" from the "Services" window (Start -> Control Panel -> System and Security -> Administrative Tools).
• By running the net start SERVICE command like this:

C:\OpenOPC37\bin>net start zzzOpenOPCService

• If you have problems starting the service, you can also try to start this in "debug" mode:

C:\OpenOPC37\src>python OpenOPCService.py debug

Stop the OpenOPC Gateway Service

This task can be completed from one of two ways:

• By clicking the Stop link on the "OpenOPC Gateway Service" from the "Services" window (Stop -> Control Panel -> System and Security -> Administrative Tools).
• By running the net stop SERVICE command like this:

C:\OpenOPC37\bin>net stop zzzOpenOPCService

Configure the way the OpenOPC Gateway Service starts

If you are going to use this service frequently, it would be better to configure it to start in "automatic" mode. To do this:

• Select the "OpenOPC Gateway Service" from the "Services" window (Start -> Control Panel -> System and Security -> Administrative Tools).
• Right-click and choose "Properties".
• Change the startup mode to "Automatic". Click "Apply" and "OK" buttons.
• Start the service (if not already started).

Implement the OpenOPC library module

Go here for the basic implementation of the library. But, if you want updated procedures using Python 3.4+, see the wiki pages.

Documentation

A PDF manual for OpenOPC is included in this repository inside the doc folder, written by the original author. Users are encouraged to also look at the OpenOPC web site for additional usage examples that may not be contained in the manual.

Credits

The authors of this package are:

Copyright (c) 2008-2012 by Barry Barnreiter (barry_b@users.sourceforge.net)
Copyright (c) 2014 by Anton D. Kachalov (mouse@yandex.ru)
Copyright (c) 2017 by José A. Maita (jose.a.maita@gmail.com)

Contact

If you need technical assistance to implement this in a larger project, go to the main site here or here for more detailed information.

License

This software is licensed under the terms of the GNU GPL v2 license plus a special linking exception for portions of the package. This license is available in the LICENSE.txt file.