Using Opc Ua Companion Specifications - Siemens SIMATIC ET 200AL System Manual

Example of user-defined server interface
A CPU should control the production of workpieces. Production begins when a production job
arrives from the higher-level control system.
The production jobs are transferred via a server method: A control system transmits
information on a workpiece by calling the server method in the CPU. This server method also
starts production.
The control system, i.e. the connected OPC UA client, should only see this one server method.
Therefore, you create a user-defined server interface in the CPU and assign the server method
to this server interface. You enable only this server interface for OPC UA clients and thus limit
the view of the CPU to this one function.
9.3.4.2

Using OPC UA companion specifications

Introduction
OPC UA is universally applicable: The standard itself does not, for example, specify how PLC
tags are to be named. It is also up to the individual user (application developer) to program
and name server methods that can be called over OPC UA.
Information modeling and standardization for devices and sectors
For applications of the same kind, it is worth standardizing your device or machine interface
with the "OPC UA toolkit".
Many different bodies and working groups have driven forward standardization and
developed a range of companion specifications.
These specifications define:
• The objects, methods and tags with which a typical device or machine is to be described.
• The namespace intended for the specified objects.
Machines are typically structured in functional or technological units, and these units are
then standardized.
Companion specifications offer machine and plant operators the benefits of a standardized
interface. For example, all RFID readers that comply with the AutoID specifications can be
integrated in the same way. This means that all RFID readers that comply with the AutoID
specifications can be addressed by OPC UA clients in the same way irrespective of
manufacturer.
Another example of companion specifications is the Euromap 77 Companion Specifications
from the injection molding machinery sector.
Communication
Function Manual, 05/2021, A5E03735815-AJ
OPC UA communication
9.3 Using the S7-1500 as an OPC UA server
245