When you start an OPC client it should immediately connect to the OPC DataHub, because the DataHub is preconfigured to act as an OPC server. If the DataHub is not running, the OPC client will attempt to start it.

If your client does not connect, you can check the DataHub configuration as follows:

1. Right click on the DataHub system-tray icon and choose Properties.
2. In the Properties window, select OPC .
   
3. Ensure that the Act as an OPC Server box is checked.

   If your OPC client requires that you hand-enter the OPC server name, use either Cogent.OPCDataHub or Cogent.OPCDataHub.1 .

   The Do not adjust OPC registry entries for this program option tells the OPC DataHub not to alter its registry settings. This is useful if you want to use the OPC DataHub with a redundancy server or some other program that modifies the DataHub's registry independently. Without this box checked, the DataHub will overwrite any external changes when it starts or when a change to the Act as an OPC Server status is applied.
   These two boxes work together, because turning the OPC server behavior on or off necessarily makes changes to the registry. Here is how you can change OPC server behavior when you also need to maintain registry settings:
   1. Uncheck Do not adjust OPC registry entries for this program. This will make the Act as an OPC Server checkbox visible.
   2. Check or uncheck the Act as an OPC Server as needed, and click Apply.
   3. Check Do not adjust OPC registry entries for this program and click Apply.
4. Click Apply button at the bottom of the Properties window to apply the change. You can view connections with the Connection Viewer.