Skip to main content


open62541 is the only open source all-C implementation of OPC UA technology, the world-wide interoperability standard for machine-to-machine communication. The software developed in substantial parts at the Fraunhofer-Institut für Optronik, Systemtechnik und Bildauswertung (IOSB) in Karlsruhe is extremely friendly for resource-constrained environments and runs on every kind of hardware, from the small embedded system to the large production plant. Now, open62541 has received the decisive seal of approval: The OPC Foundation has just announced the official certification of an OPC UA server implementation built using version 1.0 of the open source OPC UA stack open62541.

OPC UA – the Open Platform Communications Unified Architecture, is the open standard that allows any type of equipment to communicate with each other seamlessly. For example, individual sensors up to complete production lines, power plants or oil platforms, etc. can be mapped in an OPC UA server-side information model and can be accessed by multiple clients. This enables data exchange, intelligent data evaluation and process control. As a manufacturer-independent standard, OPC UA is considered a basic technology for realizing new business models in the Industry 4.0 world. OPC UA is published, developed and managed by the OPC Foundation based in the United States.

open62541 is an open-source implementation of the OPC UA technology, which is being driven forward by Fraunhofer IOSB, Germany along with the Indian software system integrator Kalycito and the Open Source Automation Development Lab (OSADL) eG, Germany. The software library is written in the C programming language, more precisely in the common subset of C99 and C ++ 98. “This means that the software can be used with all common compilers and is so resource-saving that it runs on every imaginable hardware. It also makes it possible to set up dedicated OPC UA servers as well as to integrate OPC UA-based communication into existing applications”, explains Dr. Julius Pfrommer, Group Leader Cyber-Physical Distributed Systems in the Department Information Management and Control Technology (ILT) in Fraunhofer IOSB, the lead software architect behind open62541. Bhagath Singh Karunakaran, founder and CEO of Kalycito Infotech Private Ltd. adds: “After being the first to implement Pub/Sub and demonstrate TSN readiness in early 2018, open62541 is now the first open source c-stack to be certified against the server CTT. We dedicate this success to each and every contributor”.

Open source provides a way for industry leaders to collaborate, stop re-inventing the wheel, reduce total cost of ownership and focus on their core-differentiators. The now certified software package includes the ‘Micro Embedded Device Server’ profile, which also supports subscriptions, method calls, and encryption. In addition, open62541 version 1.0 also supports communication based on the OPC UA Publisher/Subscriber model. The software is licensed under the Mozilla Public License v2.0 (MPL-2.0) which ensures that the open62541 library can be linked and distributed along with proprietary software. Only further developments of the open62541 library itself must be licensed under the MPL-2.0

The latest developments are made possible by an OSADL community project involving the following companies:

  • Balluff GmbH
  • Heidelberger Druckmaschinen AG
  • Intel Corporation
  • iss innovative software services GmbH
  • Linutronix GmbH
  • Nestfield Co., Ltd
  • Pepperl+Fuchs AG
  • Pilz GmbH & Co. KG
  • Sick AG
  • Siemens AG
  • TQ-Systems GmbH
  • WIKA Mobile Control GmbH & Co. KG

Dr. Carsten Emde, Managing Director of the Open Source Automation Development Lab (OSADL) eG thanks the participating companies for the financial support, without which the project would not have come about. At the same time, he points out that with this certification, the project is by no means complete, but the development continues – including a consistent and freely available solution for real-time Ethernet via a connection to TSN. He says: “The more companies that participate in the project, the more powerful and versatile components can be developed and contributed. The project is designed to allow companies to join at any time after the project has started, so we would like to take this opportunity to motivate other interested companies to participate.”

Further information:
Certification in German version:
Certification in French version:…ogies-embarquees/

Looking at integrating OPC UA in your products/solutions?
Checkout our SDKs
To know more about our support for Digital Transformation and IIoT device management platform
Click here