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Open source version of OPC UA spec for M2M launches

Sep 27, 2019 — by Eric Brown 1,685 views

OSADL announced OPC Foundation certification of its open source, C-developed “open62541” v1.0 implementation of the TSN-enabled OPC UA standard for M2M Ethernet communications. Kalycito has launched an open62541 starter kit that runs on a Linux-ready TQ gateway.

You may have noticed an increase in products on LinuxGizmos that support Time-Sensitive Networking (TSN), which is built into some new networking SoCs such as NXP’s Cortex-A72 based LS1028A. More recently we’ve seen products that claim to support the OPC Foundation’s TSN-enabled Open Platform Communications Unified Architecture (OPC UA), such as Advantech’s new WISE-710 gateway.

Despite the name, OPC UA (IEC 62541), which aims to standardize the myriad of machine-to-machine (M2M) protocols, is not open source. The open refers to its vendor-independent framework, as opposed to earlier standards such as the Microsoft-based COM/DCOM technology. Now the OPC Foundation has certified the first fully open source implementation of OPC UA written in C, called open62541. The implementation is developed with open source software components and can run on any architecture that supports C compilers.

OSADL conceptual diagram for open62541
(click image to enlarge)

The open62541 stack was funded and tested by the Open Source Automation Development Lab (OSADL) and co-developed by Kalycito Infotech, with significant assistance from the Fraunhofer Institute of Optronics, System Technologies and Image Processing (Fraunhofer IOSB). OSADL, which is known for its work in developing Real-Time Linux using PREEMPT_RT, as well as testing and advising on open source legal compliance and safety certifications, announced the OPC certification of an example server based on open62541 v1.0.


OPC UA enables “seamless” communications between technologies ranging from sensors to large-scale systems, thereby streamlining data exchange, intelligent data evaluation, and process control. The architecture integrates all the functionality of individual OPC Classic specifications into one extensible framework. The software allows developers to create a server-side information model for any system that can be accessed by multiple clients.

Written in C99 and C++ 98, open62541 is designed for resource-constrained environments, but also supports larger systems. The certified server was built according to the Micro Embedded Device Server OPC UA profile that also supports subscriptions, method calls, and encryption. In addition, open62541 v1.0 supports communication based on the OPC UA Publisher/Subscriber model, which cannot yet be certified.

The open62541 software is licensed under Mozilla Public License v2.0, thereby ensuring that the open source library “can be linked and distributed along with proprietary software,” says OSADL. “Only further developments of the open62541 library itself must be licensed under the MPL-2.0.” A dozen OSADL members including Intel, Siemens, and TQ-Systems, contributed to open62541.

Architecture diagram for Kalycito’s open62541-based OPC UA client server SDK for embedded targets
(click image to enlarge)

Kalycito recently released an OPC UA client server SDK for embedded targets based on open62541 that runs on Linux, Android, Windows, QNX, and other platforms. The SDK is also available in a Real-Time Linux version with PREEMPT_RT for x86 systems using Intel i210 Ethernet controllers.

The SDK features an event-based architecture and allows modifications to the information model at runtime. The models and other data types are generated from XML files.

TQ-Embedded’s MBox-Advanced (left) and MBox-R
(click images to enlarge)

There’s also a Microsoft Azure-certified Kalycito IIoT Starter Kit that preloads the open62541 SDK on two TSN-enabled embedded computers that support Linux or Windows. There’s an Intel Bay Trail based MBox-R embedded gateway and an Apollo Lake based MBox-Advanced, both with Intel i210 based GbE ports. The fanless MBox-Advanced has up to 8GB DDR3L plus 4x GbE, 2x USB 3.0, a DisplayPort, and dual M.2 slots, among other features.

OSADL General Manager Carsten Emde noted that despite the certified open62541 v1.0, there’s more work to be done. The project has entered into a Phase 2 stage to meet market demands for longevity, maturity, and commercial support. There are plans to “launch a subsequent community project that fills the gap to use the existing OPC UA PubSub over TSN software components in real products and release them to the industry and automation market,” says the OSADL OPC UA page.

Further information

The certified open62541 v1.0 example server is available for download. More information may be found on and OSADL’s OPC UA page, as well as Kalycito’s OPC UA client server SDK for embedded targets and IIoT Starter Kit pages.

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