Tsn Configuration (Ieee 802.1Q); Opc Ua Pubsub - Siemens SIMATIC NET System Manual

Basics of communication with Industrial Ethernet
1.2 Industrial Ethernet
1.2.5.3

TSN configuration (IEEE 802.1Q)

The IEEE 802.1Qcc standard describes three possibilities of the TSN configuration. The
suitable configuration method is dependent on the application example, the size of the
network and the properties of the devices.
● Distributed configuration of end devices and the network
Each device reports its requirements to the TSN switch to which it is connected. The TSN
switch distributes this information in the network. A central instance is not necessary for
this. During the assignment of the resources, the TSN switch does not require any
information about the entire network. Only the transmission path of the stream is relevant
for the configuration. The talker begins with the data transfer if at least one listener is
logged on to the stream and if the required resources are available between talker and
listener.
● Central configuration of the network and distributed configuration of the end devices
Each switch is configured by a central network management (Centralized Network
Configuration, CNC). The network management disposes of complete topology
information and information about the properties of the bridge devices. As in distributed
configuration, the end device signals its requirements to the TSN switch. The TSN switch
transmits this information to the central network management.
● Central configuration of network and end devices
All devices, including the end devices, are configured centrally. The central network
management creates a configuration for the complete system that considers all
requirements of the nodes and makes the required configuration parameters available to
each node.
1.2.5.4

OPC UA PubSub

OPC UA as manufacturer-independent interface
For data exchange on the application level, the OPC UA interface can be used for the TSN.
OPC was originally developed on the basis of DCOM, a system for remote procedure calls
from Microsoft. The acronym OPC was the abbreviation for OLE for Process Control. The
goal was to create an open standard for data exchange in automation technology. For the
OPC UA further development introduced in 2006, a communication stack was implemented
that is independent of COM/DCOM and the Windows operating system. Since then the
acronym OPC UA stands for Open Platform Communications Unified Architecture.
Publish-Subscribe-Stack for cyclic data exchange
OPC UA uses the client-server principle. The sequence of query of the client and response
of the server ensures a reliable data exchange via a secured connection. For cyclic data
exchange, often also with multiple participants (multicast), this principle, however, is only
suitable to a limited extent. The Publish-Subscribe communication, shortened "PubSub", was
developed additionally for this special application.
A Publisher is the sender of news, Subscriber(s) are the receivers. The Publish-Subscribe
communication uses UDP, TSN or MQTT (for the cloud connection) as lower-level protocols.
If only TSN-capable devices are used for a transmission link, the OPC UA PubSub enables a
deterministic data transfer on the application level ("OPC UA over TSN").
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System Manual, 09/2019, C79000-G8976-C242-10
Industrial Ethernet