Real-time data flow with DDS and TSN

~ Could a DDS-TSN standard provide the open framework we’ve been missing? ~

In real-time computing systems, using a Data Distribution Service (DDS) is an increasingly common way to provide dependable and documentable data flows for safety and mission critical applications.  Here, Martin Frederiksen, managing director of embedded computing specialist Recab UK, introduces the combination of DDS with Time Sensitive Networking (TSN) technologies, to enable real-time Quality of Service (QoS) and deterministic networking for critical data flows.

Many operators, manufacturers and systems integrators in transportation, defence and energy generation and distribution are already using DDS with real-time computer systems. One huge benefit is that DDS provides comprehensive QoS policies, for configuring how data is delivered. TSN, a new set of IE 802.1xx standards, brings the possibility to prioritise particular data packets injected into the network and use time-aware shaping to ensure they are prioritised over other, ‘best effort’ traffic at all times, so even when your network usage hits 100 per cent, critical messages get through.

TSN can therefore be used to achieve very low latency and determinism, a great combination with the strengths of DDS. TSN can also be used to add redundancy and increase availability to an Ethernet network. This enables users to consider Ethernet over CAN, MIL-1553b or other older infrastructure standards. Ethernet brings cost and lower complexity benefits, plus some degree of future-proofing.

A number of professional bodies, including the Industrial Internet Consortium, are calling for the combined use of DDS and TSN, which would guarantee a standards-based end-to-end solution capable of providing QoS-aware deterministic communication. In response, the OMG is currently working on a standard to integrate DDS applications in TSN-enabled networks.

The OMG’s preliminary research, which will form the basis of the new standard, looks positive. The DDS specifications cover software components higher on the IIoT connectivity stack, whereas TSN defines the hardware interfaces and signaling at the lower layers of the stack, meaning that all bases are covered. Both are designed for time-sensitive applications and are horizontal standards, applicable to several vertical markets.

There are many benefits to implementing TSN networking, starter kits, development devices and full mil-spec switches are available from Recab UK, now. We have several reference set-ups and demo configurations to get businesses started and packages of support time available to help them realise a meaningful test and development platform quicker.

For defence land vehicle applications, products from the Relyum range by SoC-e are already in use. The RELY-MIL-SWITCH-ROUTER, part of Relyum’s range, features up to 20x 1G copper and up to 6x 1/10G fibreoptic ports. Like the test and development units, these RELY-MIL switches and switch-routers support the most comprehensive set of TSN standards available today. Relyum equipment also supports multi-layered security, redundant network topologies aiming high-availability communications, as well as edge-computing and time-server functionalities, maximising the return on investment and helping to avoid additional systems in weight sensitive applications.

Recab UK works closely with RELYUM to provide solutions that meet its customers’ requirements today, but can also be upgraded throughout their long service life, particularly during the introduction of new standards. For more information, visit www.recabuk.com.