Rerunning the Discovery Agent for an OPC Server

IMPORTANT: When you are using the OPC Discovery Agent, the individual tag information does not automatically display in the system tree; only the top level initially displays. As you expand each level, the OPC Discovery Agent gets and displays the data for that level. For this reason, the OPC Item Status column may not display the status you expect.

Because the OPC Server is browsed only when requested (that is, when a branch is expanded), when you rerun the OPC Discovery Agent, the OPC Item Status field updates only those items already displayed in the spreadsheet. When you browse for items for the very first time, the status field will always display New, regardless of whether there were changes to the OPC Server since the first time it was browsed. Only those items already displayed in the spreadsheet show an updated status.

To rerun the Discovery Agent:

  1. Launch the Discover and Auto Configure application and follow the Discovery Agent Selection Wizard steps to extract item information from the OPC server. The item information is displayed in the Discovery Agent section of the spreadsheet.

NOTE: The OPC Item Status column displays New for all rows.

  1. Perform any applicable tasks you need to in the spreadsheet, including selecting tags, defining tags for the target database, saving a .DAC file, adding tags to the database, and so on.
  2. From the File menu, choose Run Discovery Agent. You are prompted with the question "Do you want to run the Discovery Agent again?"
  3. Click Yes. The Discovery Agent Selection Wizard opens at the Select Local or Remote OPC Server page with the previous selections displayed; that is, if you had previously browsed an OPC server on a remote machine, the Remote Machine option is selected and the machine name is displayed.
  4. Leave your selection as is, or change it to the other option and click Next to go to the Select an OPC Data Access Server dialog box..
  5. Select an OPC server and click OK to go to the Summary page. You can select the same OPC server or a different one.
  6. On the Summary page, click Finish. The item information is extracted from the OPC server again. For each item that is being browsed again, the Discovery Agent tool compares the item information from the new extraction with the items displayed in the spreadsheet and then updates the spreadsheet.

The status of each item is updated in the spreadsheet. The status can be New, Modified, Not Found, or blank (that is, no change). For more information, refer to the Discovery Agent Section of the Discover and Auto Configure Application topic.

  1. Click the OPC Item Status column to sort the statuses and view the differences.


See Also