When someone runs CSWorks Pipes and Tanks Demo application for the first time, the first question is: where all this data for pipes, tanks and valves comes from?

CSWorks installation package includes LiveData Emulator OPC Server component that simulates mixing process and accepts input from the user when he/she opens and closes the valves and changes mixing speed. LiveData Emulator OPC Server is useless for real-world applications but works well as a simple data source for the demo.

In order to make sure that CSWorks displays actual data supplied by this OPC data source, you may want to set up a quick demonstration and see how numbers are changing simultaneously in the demo and in your favourite OPC viewer application.

First off, if you just run OPC viewer on the demo machine and connect it to CSWorks LiveData Emulator OPC Server you will see some tags changing, but those changes won't be in sync with the demo values. This happens because of the way COM/DCOM (and OPC) works.

Unless you configured it otherwise, CSWorks LiveData Service runs under Network Service user account - a special Windows account many system services run under. When CSWorks LiveData Service is being told to access an OPC server (Emulator OPC Server in our case), it instantiates it through COM/DCOM infrastructure. By default, a COM server is started as a separate process on behalf of the launching user - Network Service. If you have a look at the process list while CSWorks demo is running you will see LiveData Emulator process running under Network Service account.

Now you run an OPC viewer application and connect it to CSWorks LiveData Emulator OPC Server. Have a quick look at the process list again - you will see that now you have another instance of LiveData Emulator process running under your personal account. So you have two emulators supplying different data to CSWorks and to the OPC viewer.

Let's make both CSWorks and OPC viewer use the same instance of the emulator. Please use Windows Service Manager to configure CSWorks LiveData Service so it runs under you personal account (say, Administrator). Also use DCOM configuration tool (dcomcnfg.exe) to make sure that LiveData OPC Emulator:

  • can be launched (Properties - Security - Launch and Activation Permissions) and accessed (Properties - Security - Access Permissions) by your personal account;
  • is instantiated runs under interactive user account (Properties - Identity).

This screenshot shows what has to be done.

After doing that, restart CSWorks LiveData Service and your OPC viewer, so they start using properly configured LiveData OPC Emulator server.
The screenshot shows three application windows: two Internet Explorer instances with CSWorks demo application, and a third-party OPC viewer that is configured to receive updates for "storage.numeric.reg01" tag. This is the item that CSWorks demo application uses to store Tank 1 fill level.

As CSWorks LiveData Emulator changes Tank 1 fill level, you see it changing in all three windows simultaneously. Perfect, we get the same data in all three windows.

After demonstrating CSWorks live data in action, do not forget to revert all changes made in DCOM configuration and service manager.