The advantages of using OPC UA PubSub together with TSN technology are manifold: TSN offers deterministic and time-synchronized communication over Ethernet networks. By combining OPC UA PubSub with TSN, the user can achieve reliable and predictable data exchange between devices. This is crucial for industrial automation, where timing and synchronization are critical for coordinated actions and control loops.

Furthermore, the low-latency capabilities of TSN combined with OPC UA PubSub's ability to publish data asynchronously and enable real-time performance for time-critical applications. This is particularly important in scenarios where fast data exchange is required for tasks such as control and monitoring.

OPC UA also provides standardized data modeling and information representation. By using OPC UA PubSub with TSN, the user can efficiently distribute this standardized data across the network, ensuring consistent and coherent information exchange between devices. OPC UA is also known for its focus on interoperability: In combination with TSN, it enables seamless communication across different devices, vendors and systems, even in complex multi-vendor environments.

TSN also supports redundancy mechanisms to improve network reliability. The decoupled architecture of OPC UA PubSub ensures smooth handling of network interruptions and guarantees data integrity and reliability even in the event of failures. Last but not least, TSN's traffic shaping and scheduling mechanisms help to reduce network congestion and conflicts. OPC UA PubSub, with its ability to publish only relevant data to subscribers, further optimizes network usage and minimizes unnecessary data transfers.

Hardware-independent stack

The architecture of the eTSN stack with proprietary components (light blue).

© BE.services

Together with Offenburg University of Applied Sciences, BE.services has set itself the task of developing a low-footprint OPC UA PubSub TSN stack that can be ported to various platforms and components in the TSN network. In addition to the resource requirements, the portability of the stack was also to be optimized.

The resulting eTSN (enable TSN) stack can be used, for example, on Intel or TI platforms in a C2C communication as well as on platforms with TSN-compatible Ethernet interfaces, for example Intel (wireless) or Renesas, as bridges or as a device implementation. The corresponding software development kit can be implemented both with an operating system and on a bare-metal platform.

The solution is based on the following components

• a resource-optimized Matrikon eFlex OPC UA stack
• a proprietary IEEE 802.AS PTP stack to ensure hardware portability and independence
• a cost-effective test suite environment for monitoring latency, jitter and synchronization of the TSN network.

The software development kit allows implementation on different platforms and supports the implementation of hardware-specific IEEE 802.1 standards. The already published specifications of OPC UA FX for C2C are supported. The following specifications, such as C2D, will also be considered after the official release.

The implementation phase

The author: Dimitri Philippe is Managing Director at BE.services.

© BE.services

BE.services has already started the design work for the configuration of TSN networks. Among other things, the focus is on target devices with low memory requirements. eTSN can be seen at the SPS trade fair with controller, bridge and device implementations on the target hardware from Intel, Renesas and TI. The stack is already available as a beta version. By mid-2024, eTSN will be released as a single stack with a focus on low-footprint platforms with a memory of only 300 kB RAM and 300 kB flash.