The Time Sensitive Networking standards developed by the TSN working group of the IEEE 802.1 form the basis for the convergence of IT Ethernet with field level networks requiring deterministic features. The seamless communication between machines, objects and services is enabling new automation models and the Industrial IoT (“Industry 4.0”). In addition, Time-Sensitive-Networking enables the transmission of time-critical and “common” data over the same Ethernet network.
Therefore the new IEEE standards can be used in order to realize systems in which safety applications are connected over the same Ethernet network as e.g. streaming data. This results in significant simplification of network infrastructure and layout and allows for extensive scalability and flexibility within industrial networks.
EBV Elektronik demonstrates the benefits of TSN technology within industrial safety at the Embedded World Fair 2017 in Nuremberg, Germany (hall A3, booth 229). The showcased demo which was created in close cooperation with the Fraunhofer IOSB-INA in Lemgo is based on the TSN Sub-Standard IEEE 802.1Qbv “Time- aware shaper”.
This standard defines up to 8 queues per port for forwarding traffic. Frames are assigned to queues based on Quality of Service (QoS) priority. The time-aware shaper (TAS) mechanism blocks all ports except one based on a time schedule in order to prevent delays during scheduled transmission. In other words, there is a gate in front of each queue which opens at a specific point of time which is reserved for this queue guaranteeing network paths for time critical traffic over standard Ethernet.
In the demo the capabilities of this time-aware shaping mechanism are illustrated using the distance between a light barrier and a motor which represents a potential hazard. Without using TSN the distance is comparably large. In contrast, if IEEE 802.1Qbv is applied to the setup, the detection of movement can be performed in close proximity to the source of danger.
Using an IP camera in the same system without TSN increases the network traffic to a level where the system shuts down completely without reaching through the light barrier (fail safe). With TSN however, the latency of the safety critical traffic remains at a guaranteed level due to the traffic scheduling and the system remains active.
The demo is based on the Argon LS1021A Time Sensitive Network Switch Board, a low cost, full featured, open source next generation IoT gateway reference design based on NXP’s SJA1105T TSN switch and QorIQ LS1021A embedded processor. The safety control is based on hardware from Phoenix Contact.
The safety controlled inputs are coupled onto Ethernet running PROFINET RT saddled up on TSN via a bus coupler. This creates the advantage of being able to profit from the device modelling, machine-to-machine communication and other capabilities of PRFOINET as well as from the efficiency and sustainability of standardized IEEE 802.1 deterministic technology through TSN. In the demonstration the traffic runs through one LS1021A-TSN board to another LS1021A-TSN Board and furthermore to a SPS and safety outputs controlling a motor. This motor is stopped in case someone reaches through the light barrier.
For more information about NXP’s Time-Sensitive Network Solution for Industrial IoT click here.
Special thanks also to the Fraunhofer IOSB-INA, NXP and Phoenix Contact for the close cooperation during this project.