OpenOPC-DA 1.5.1

OPC-DA (OLE for Process Control) toolkit for Python 3.7+

OpenOPC for Python 3.7+ is a descendent of https://openopc.sourceforge.net with modifications for Python 3 and distutils.

About OpenOPC

OpenOPC for Python is a free, open source OPC (OLE for Process Control) toolkit designed for use with the popular Python programming language.

Python Packages

Python package releases can be found at:

https://pypi.org/project/OpenOPC-DA

for:

Windows Python 64-bit version (does not include opc-service console application) Windows Python 32-bit version (needs pywin32 for opc-service) Linux x86-64 (does not include opc-service console application)

Installation

From pypi:

pip install OpenOPC-DA

Software Developers

If you elected to install the OpenOPC Development library during the installation process, then you’ll need to also download and install the following packages in order to develop your own Python programs which use the OpenOPC library:

1. Python 3.7+ https://www.python.org/download/

2. Python for Windows Extensions (pywin32) https://github.com/mhammond/pywin32

3. Pyro5 https://github.com/irmen/Pyro5

Of course, Python is necessary on all platforms. However the other packages may be optional depending on your configuration:

1. Win32 platform, using the OpenOPC Gateway Service

Pywin32: optional Pyro5: required

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

Pywin32: required Pyro5: optional

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

Pywin32: not applicable Pyro5: required

In order to get the most from the OpenOPC package, Windows developers are encouraged to install both Pywin32 and Pyro. Using Pyro 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.

Documentation

A PDF manual for OpenOPC is included in this installation inside the “doc” folder. Users are encouraged to also look at the OpenOPC web site for additional usage examples that may not be contained in the manual.

EXAMPLE - Minimal working program:

import OpenOPC
opc = OpenOPC.client()
opc.connect('Matrikon.OPC.Simulation')
print(opc['Square Waves.Real8'])
opc.close()

OPC DA Automation Wrappers

A registered wrapper dll is required to access the OPC server. These wrappers are normally installed and registered when the OPC Server is installed.

The default classes supported are:

OPC DA Automation Wrapper 2.02
Matrikon.OPC.Automation (opcdaauto.dll)
Graybox.OPC.DAWrapper (gbda_aut.dll)
HSCOPC.Automation (PKS OPC Server dll)
RSI.OPCAutomation (rsiopcauto.dll from Rockwell)
OPC.Automation (opcdaauto.dll from OPC Foundation)

These classes can be overrided by the OPC_CLASS environment variable.

OpenOPC Console App Executables

After an OpenOPC package has been installed in a Python environment, two console applications can be found in the scripts directory on Windows or bin directory on Linux:

opc.exe, the OpenOPC client
opc-service.exe, the OpenOPC gateway service for Python 32-bit for Windows only

To run opc-service from an active virtual environment, the following dlls will have to be copied to scripts directory once pywin32 is installed:

python3x.dll found in the main Python installation directory
pythoncom3x.dll found in the virtual enviornment's Lib\site-packages\pywin32_system32
pywintypes3x.dll found in the virtual enviornment's Lib\site-packages\pywin32_system32
pythonservice.exe found in the virtual enviornment's Lib\site-packages\win32

pywin32_system32 and win32 directories are created once pywin32 is installed.

OpenOPC Gateway Service (requires Python 32-bit for Windows)

The gateway service can be installed, debugged, and removed by using the opc-service console app by executing the following on a Command Prompt with Administrative rights:

opc-service install
opc-service debug
opc-service remove

To display the usage help text execute the following on a Command Prompt:

opc-service

Before installing the service on a machine, check that the OPC Server has a OPC Automation DLL installed. By default the service will use the loop back IP address 127.0.0.1, to allow the service to communicate over the network set OPC_GATE_HOST to the IP of the host before installing the service.

OpenOPC Command-line Client

OpenOPC includes the only publically available command-line OPC client. Unlike graphical clients, it can be easily used in scripts or batch files. And because of its piping capability (i.e. chaining commands together), it is far more powerful than other OPC clients

1. Get a listing of the available OPC servers on your computer by going to the command prompt and entering:

opc -q

2. Set your prefered OPC server as the default by setting the system wide enviornment variable OPC_SERVER. (On Windows you can do this by going to Control Panel > System > Advanced > Environment Variables):

OPC_SERVER=Matrikon.OPC.Simulation

3. Display OPC server information via the Win32 COM connection:

   opc -i

4. Test to see if the OpenOPC Gateway Service is functioning by entering:

opc -m open -i

5. Test some of the other commands available using the OPC Command Line Client. To get started, try entering the opc command without any arguments in order to see the help page:

opc

To read an item from your OPC server, just include the item name as one of your arguments. For example, if you’re using Matrikon’s Simulation server you could do:

opc Random.Int4

To read items from a specific OPC server you have installed, include the -s switch followed by the OPC server name. For example:

opc -s Matrikon.OPC.Simulation Random.Int4

To list available items:

C:\> opc -f Random.*Int*
Random.Int1
Random.Int2
Random.Int4
Random.UInt1
Random.UInt2
Random.UInt4

To read values of items every 60 seconds, logging the results to a file until stopped by Ctrl-C…:

C:\> opc Random.Int4 Random.Real8 -L 60 >data.log

Command usage summary:

C:\> opc
OpenOPC Command Line Client 1.1.6
Copyright (c) 2007-2008 Barry Barnreiter ([e-mail])

Usage:  opc [OPTIONS] [ACTION] [ITEM|PATH...]

Actions:
  -r, --read                 Read ITEM values (default action)
  -w, --write                Write values to ITEMs (use ITEM=VALUE)
  -p, --properties           View properties of ITEMs
  -l, --list                 List items at specified PATHs (tree browser)
  -f, --flat                 List all ITEM names (flat browser)
  -i, --info                 Display OPC server information
  -q, --servers              Query list of available OPC servers
  -S, --sessions             List sessions in OpenOPC Gateway Service

Options:
  -m MODE, --mode=MODE       Protocol MODE (dcom, open) (default: OPC_MODE)
  -C CLASS,--class=CLASS     OPC Automation CLASS (default: OPC_CLASS)
  -n NAME, --name=NAME       Set OPC Client NAME (default: OPC_CLIENT)
  -h HOST, --host=HOST       DCOM OPC HOST (default: OPC_HOST)
  -s SERV, --server=SERVER   DCOM OPC SERVER (default: OPC_SERVER)
  -H HOST, --gate-host=HOST  OpenOPC Gateway HOST (default: OPC_GATE_HOST)
  -P PORT, --gate-port=PORT  OpenOPC Gateway PORT (default: OPC_GATE_PORT)

  -F FUNC, --function=FUNC   Read FUNCTION to use (sync, async)
  -c SRC,  --source=SOURCE   Set data SOURCE for reads (cache, device, hybrid)
  -g SIZE, --size=SIZE       Group tags into SIZE items per transaction
  -z MSEC, --pause=MSEC      Sleep MSEC milliseconds between transactions
  -u MSEC, --update=MSEC     Set update rate for group to MSEC milliseconds
  -t MSEC, --timeout=MSEC    Set read timeout to MSEC mulliseconds

  -o FMT,  --output=FORMAT   Output FORMAT (table, values, pairs, csv, html)
  -L SEC,  --repeat=SEC      Loop ACTION every SEC seconds until stopped
  -y ID,   --id=ID,...       Retrieve only specific Property IDs
  -a STR,  --append=STR,...  Append STRINGS to each input item name
  -x N     --rotate=N        Rotate output orientation in groups of N values
  -v,      --verbose         Verbose mode showing all OPC function calls
  -e,      --errors          Include descriptive error message strings
  -R,      --recursive       List items recursively when browsing tree
  -,       --pipe            Pipe item/value list from standard input

If you experience any unexpected errors, please check the FAQ on https://openopc.sourceforge.net for additional help.

If after reading through the FAQ you still require additional help, then the author of this package would be happy to assist you via e-mail. Please see the project website for current contact information.

Technical Support

If you have any questions, bug reports, or suggestions for improvements please feel free to contact the author at:

[e-mail]

While I cannot always guarantee a quick response, I eventually respond to all e-mails and will do my best to solve any issues which are discovered.

Thanks for using OpenOPC for Python!

Credits

Copyright (c) 2008-2012 by Barry Barnreiter ([e-mail]) Copyright (c) 2014 by Anton D. Kachalov ([e-mail]) Copyright (c) 2017 by Michal Kwiatkowski ([e-mail]) Copyright (c) 2023 by j3mg

https://openopc.sourceforge.net/ https://github.com/ya-mouse/openopc https://github.com/sightmachine/OpenOPC https://github.com/mkwiatkowski/OpenOPC