This chapter has answers to the most common troubleshooting questions that may arise. Any other known, unresolved issues are discussed in the README.txt which is included in the distribution archive. Please read that file and this page before contacting Cogent for help.


For responses to other common questions and issues, please see also the Cogent Community Forum Frequently Asked Questions.

22.1 I can't get a connection.
22.2 Windows Error Messages
22.3 OPC DataHub Error Messages
22.4 Messages from Excel
22.5 Excel not updating

I can't get a connection.

Check the following:

    Is your connection to the Internet and/or network up and functioning normally?

    Does your firewall allow a local program (like OPC DataHub) to act as a server?

    Does the OPC DataHub run OK?

    Is the DataHub installed and configured correctly?

    For drag and drop operations, is the Drag & Drop Style at the bottom of the Data Browser set to MS-Office (Excel/Word)?

    Are you using the DataHub web server and is Skype installed on the same machine? There is a default option in Skype (follow the Tools - Options - Connection menus) to use port 80 as an alternative for incoming connections. You will need to either disable this, or change the port number of the DataHub's web server to something other than 80.


Windows Error Messages

For a list of Windows error messages, including those for TCP and DDE, please refer to AppendixH, Error Messages.


OPC DataHub Error Messages

Here is a brief explanation of some of the more common error messages you might encounter when using the OPC DataHub:

License failure: License in use by master

There are two possible reasons for this message:

    One Cascade DataHub is tunnelling to another DataHub on another computer and that DataHub is tunnelling back to the first.

    The Cascade DataHub is tunnelling to itself.

Either of these are probably due to misconfiguration. Check your configuration files to ensure that only one Cascade DataHub is configured to be a master in any master/slave pair, and that no DataHub is tunnelling to itself.


Messages from Excel

When you save and close a spreadsheet connected to the DataHub and then attempt to reopen it, you may get one or more messages, depending on your security settings in Excel, or other circumstances. Here's a summary of each message, and what to do:

This document contains macros. Enable them?

Click Enable Macros.

This workbook contains links. Update them?

Click Update. If the DataHub or Connect is already running, all the links should then update automatically. If not, you may get a #REF! entry in some cells, and the next message (see below) will probably appear.

Remote data not accessible. Start the DataHub or Connect?

Click No. At this point the best thing to do is close the worksheet, start the requested program, and then reopen the worksheet. When you update the spreadsheet (see above) this time you won't get any #REF! entries.


Excel not updating

The default settings in Excel allow you to drag and drop from the OPC DataHub into your spreadsheet and see the data updating automatically. Sometimes however the Excel configuration may have been changed so that you do not see this. For example, if you drag a data point into Excel and you get the first value, but then nothing after that, you may want to check the following settings.

  1. From the Tools menu, choose Options to open the Options window.
  2. Ensure that the Automatic option in Calculation is selected.
  3. Ensure that the Update remote references option in Workbook options is selected. Then close the Options window.
  4. From the Edit menu, choose Links to open the Edit Links window.
  5. Ensure that the Automatic option for Update is selected. Then close the Edit Links window.

For responses to other common questions and issues, please see also the Cogent Community Forum Frequently Asked Questions.