Create a new OPC DA connection

When you configure an OPC DA Client worksheet, you must select the connection that the client will use. This task describes how to create that connection.

Before you begin this task, you should know the communication and security settings for the OPC DA server to which you want to connect. If you do not, contact the server administrator.

To create a new connection to an OPC DA server:

1. Do one of the following:

   • On the Insert tab of the ribbon, in the Communication group, click OPC Client, and then select OPC DA Connection from the drop-down list; or

   • In the Comm tab of the Project Explorer, expand the OPC DA folder, right-click the Connections folder, and then click Insert on the shortcut menu.

   The Server Connection dialog box is displayed.

   

2. In the Connection Name box, type a name for the connection.

   This name will be displayed in the OPC DA > Connections folder in the Project Explorer, and it is the name you will look for when you configure the OPC DA Client worksheet.

3. In the Specification list, select the specific OPC specification that is used by the OPC Server:

   • Data Access 2.XX

   • Data Access 3.00

4. In the Host Name box, do one of the following:

   • Select the name or address of the computer that hosts the OPC Server. Hosts should broadcast their availability on the network. If the host you want does not appear in the list, click Refresh to update the list.

   • If you want to be able to change the host name during project run time, type an appropriate string expression (for example, {MyEndpointUrl}). When the OPC DA Client Runtime task is started, it will get the value of the string expression and then connect to that host. Please note this happens only when the task is started, which typically happens when the project itself is run. If the value of the string expression changes after the task is started, the task must be restarted in order to get the new value and then connect to the new host. To restart the task while the project is running, either use the Runtime Tasks dialog box or call the EndTask and StartTask functions.

5. In the Server Url list, select a specific OPC Server process on the selected host. If the process you want does not appear in the list, click Refresh to update the list from the host.

6. Click OK to save your changes and close the Server Configuration dialog box.

   The connection is saved in the OPC DA > Connections folder in the Project Explorer.