OPC UA Client
PLCnext Technology controllers include an embedded OPC UA client which is integrated alongside the controller runtime. In the OPC UA architecture, the OPC UA client is the data consumer and the OPC UA server the data provider. The OPC UA client sends a data request to the OPC UA server and the server returns the requested data to the client. This enables the client direct access to the data made available by the server.
The OPC UA client and OPC UA server are represented by the 'OPC UA' icon in the PLANT. Via this tree node, the client and server can be configured in PLCnext Engineer. The OPC UA configuration data are part of the PLCnext Engineer automation project and written to the controller with the project. The OPC UA client loads the project during the controller start and automatically executes it.
Server-client communication
The communication between the server and its clients complies to the OPC Unified Architecture protocol. OPC Unified Architecture (UA) is a standardized protocol for the industrial machine-to-machine communication. It was defined by the OPC Foundation. Compared to previous OPC versions, OPC UA provides a new information model with improved semantic structuring of machine data, such as process data item values or parameters. OPC UA considerably facilitates the communication between server and clients.
In addition to the OPC UA Standard, a PLCopen standard defines an information model which has been adapted to the special requirements of automation applications. It specifies the information model an OPC UA server has to provide for the data of IEC 61131-compliant controllers to the environment. Visit the PLCopen website for further details.
Configuring the OPC UA client in PLCnext Engineer
Configuring the OPC UA client comprises the following procedures:
| Further Info
Refer also to the PLCnext Info Center for additional information about the OPC UA components and their configuration. |