OPC UA Client Configuration

Connection

Create

Click on the Create button to specify a name for the connection and thus to create a new connection with basic settings. This opens the following input dialog for entering the connection name.

Enter a name and confirm by clicking on OK.

The connection data point _<connection_name> with the set parameters is created at type _OPCUAServer (in a redundant project a data point with the name "_<connection name>_2" is created automatically for the redundant WinCC OA server) by clicking on Apply. If you click on the OK button the connection data point is created with the set parameters and the configuration panel is closed. To close the configuration panel without creating the connection data point (if not already done before) click on Cancel.

In order to change the configuration select the appropriate connection name from the combo box. Parameter changes regarding the connection establishment will not be applied until the next connection establishment. This means that if a connection is already established, it has to be deactivated and activated again (see description of Active check box below). Please note that every configuration change has to be applied by clicking on the Apply button before it takes effect.

Remove

Click on the Remove button to delete the selected connection (and thus also the connection data point or data points, respectively, in case of a redundant configuration). Note that removing a connection is not effective until the Apply button is clicked.

Existing subscriptions can be kept when removing a connection (see figure below) to be reassigned to a new connection (see Configuration of a Subscription).

Device description

You can add/change a custom description for the created connection in the corresponding project language via the Device description text field. The default description in every project language is "_<connection_name>" and is shown after reopening the configuration panel.

Settings

Reconnect Timer

Specify a time in seconds after which the driver tries to reconnect to the server in case of a connection breakdown. By default the timer is set to 10 seconds.

Connection tab

Active

Tick this check box to activate the connection to the OPC UA server. This setting is not effective until the Apply or OK button is clicked. A created and configured connection can be deactivated at any time. Thereby the connection data point is not deleted and the connection can be reactivated anytime. The status display changes from "Connected" to "Not connected" if a connection has been deactivated. If a connection has been deactivated, the driver does not communicate with the corresponding OPC UA server anymore. Therefore, it is possible to avoid alarms during maintenance work on the OPC UA server.

If a connection is deactivated the connection state is not mapped to the data point elements configured for the connection (see Definition of the Peripheral Address of the OPC UA Driver). This means that a deactivated connection is not detectable on these data point elements and the invalid bit of these values is not set (see also Connection deactivation and invalid bit settings).

Server URL/URI

Enter the URL to the server to which you want to connect (TCP/IP address and port) or the URI which shall be converted to a URL by a Local Discovery Server (refer to OPC UA Discovery for further information). The address must be accessible.

Examples for the server URL address:

opc.tcp://localhost:4840

opc.tcp://host:51234/UA/UA_Server

Example for a server URI address:

urn:MyServerUri

Authentication

Enter the access data for the server depending on the selected mode.

• Anonymous - no user and password defined, the client tries to connect with the user Anonymous (see also User Authentication).

• Username/Password - the format for the input is <user_name>:<password>. The password is displayed encoded. If the input field is left empty, the client tries to connect with the user Anonymous.

• User certificate - define the appropriate user certificate (e.g. myCert.der). The file is browsed in the certificate directory of the client.

Security

Strategy

Choose a security policy:

• None
• Basic128Rsa15
• Basic256
• Basic256Sha256
• Aes128Sha256RsaOaep
• Aes256Sha256RsaPss

For further information see Security Policy.

Message Mode

Choose a message security concept - None, Sign or Sign&Encrypt. If you have selected None from the security policy, the message security concept is automatically also None and the selection of another message concept is not possible. If you select another security policy as None either Sign or Sign&Encrypt are available for the message security concept.

For further information see Message Security Concept.

Client certificate

Name of the client certificate which is accepted for the server. The certificate name has to be entered without path specification and file extension and is written to the _OPCUAServer.Config.Security.Certificate data point element of the server connection data point.

If the field is empty, the client uses the default certificate, which is delivered by WinCC OA.

See also Certificates.

Redundant Server

Active

Tick this check box to set the connection to the redundant OPC UA server to active.

Server URL

Enter the URL to the server to which you want to connect (TCP/IP address and port) or the URI which shall be converted to a URL by a Local Discovery Server (refer to OPC UA Discovery for further information). The address must be accessible.

In addition to an accessible server URL also the link, which is returned by the server during Discovery, must be accessible (e.g. in case of several network cards).