opcua - EPICS Device Support for OPC UA

EPICS Device Support module for interfacing to the OPC UA protocol. The architecture allows using different implementations of the low level client library.

Linux and Windows native builds are supported.

Status

The module is under development, but releases are stable and robust.

There are two choices for the low-level OPC UA client library:

1. The commercially available Unified Automation C++ Based OPC UA Client SDK.
   This is the original implementation.

2. The open source client of the open62541 project SDK.
   This integration is relatively new (2024) and hasn't seen much in-production use yet.

Prerequisites

• A C++ compiler that supports the C++11 standard.
  Microsoft Visual C++ needs to be from Visual Studio 2015 or newer. g++ needs to be 4.6 or above.

• EPICS Base 3.15 (>= 3.15.7) or EPICS 7 (>= 7.0.4).

• The gtest module if you want to compile and run the unit tests that are based on Google Test.

Using the Unified Automation Client SDK

• Unified Automation C++ Based OPC UA Client SDK (1.5/1.6/1.7 are supported, as well as their evaluation bundles; 1.8 is having trouble).

• For OPC UA security support (authentication/encryption), you need openssl/libcrypto on your system - both when compiling the SDK and when generating any binaries (IOCs).

• In CONFIG_SITE.local, set UASDK to the path of your SDK installation.

• For more details, refer to the README.md in the devOpcuaSup/UaSdk directory.

Using the open62541 SDK

• The open62541 SDK
  Choose a recent release (1.2 and 1.3 are supported). Download the sources using GitHub releases, not through the project website.

• For OPC UA security support (authentication/encryption), you need openssl/libcrypto on your system - both when compiling the SDK and when generating any binaries (IOCs).

• In CONFIG_SITE.local, set OPEN62541 to the path of your SDK installation.

• For more details, refer to the README.md in the devOpcuaSup/open62541 directory.

Building the module

This is a standard EPICS module.

Inside the configure subdirectory or one level above the TOP location (TOP is where this README file resides), create a file RELEASE.local that sets EPICS_BASE and GTEST to the absolute paths inside your EPICS installation. The GTEST module is needed to compile and run the tests. Not defining it produces a clean build, but without any tests.

Configure the compiler on Linux to use the C++11 standard by adding

USR_CXXFLAGS_Linux += -std=c++11

to the CONFIG_SITE file (or one of the host/target specific site configuration files).
It is preferable to set this option globally in EPICS Base.

The configuration necessary when building against a specific client library is documented in the README.md file inside the respective subdirectory of devOpcuaSup.

Using the module

IOC applications that use the module need to

• add an entry to the Device Support module in their RELEASE.local file
• include opcua.dbd when building the IOC's DBD file
• include opcua in the support libraries for the IOC binary.

Documentation

Sparse, but getting better.

The documentation folder of the Device Support module contains the Requirements Specification (SRS) giving an introduction and the list of requirements that should convey a good idea of the planned features.

The Cheat Sheet explains the configuration in the startup script and the database links.

Binary Distribution

Please look at the "Assets" sections of specific releases on the release page for the binary distribution tars. These tars contain an EPICS module with a binary Linux shared library (libopcua.so.<version>) that contains (embeds) the Unified Automation low-level client.

In your build setup, the module from the binary distribution can be used like a support module built from source. The binary device support is fully functional and can be used without limitations or any fees.

You need to download the binary distribution tar that matches your Linux distribution and the exact EPICS Base version, else you will not be able to create IOCs.

Feedback / Reporting issues

Please use the GitHub project's issue tracker.

Credits

This module is based on extensive prototype work by Bernhard Kuner (HZB/BESSY) and uses ideas and code snippets from Michael Davidsaver (Osprey DCS).

Support for the open62541 client library and many fixes and new features were added by Dirk Zimoch (PSI) with additional help from Carsten Winkler (HZB/BESSY).

The end-to-end test suite is a reduced clone of the test application that has been developed at the ESS by Ross Elliot and Karl Vestin.

License

This module is distributed subject to a Software License Agreement found in the file LICENSE that is included with this distribution.