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TOP Server Quick Client Performance Tips

I am using the TOP Server OPC Quick Client and I notice that when I have it open at the same time as I have my regular client application open, there is a performance difference, sometimes large? Is there a problem with how many clients the TOP Server can handle? What can I do about this as I like to use the OPC Quick Client as a troubleshooting tool.

The TOP Server doesn't necessarily limit you on the # of clients that can be connected, and we have many applications with large # of clients connected to them without any performance issues.

Understanding why the Quick Client can have such a performance impact starts with how people first see the Quick Client.

The Quick Client is the way that many people get their first impressions of how fast the TOP Server can go - that's why it is easily launched from the TOP server toolbar.  When the Quick Client connects to the TOP Server, by default it subscribes to EVERY tag in your tag database and requests an update rate of 50 ms.  That update rate is fast, and depending on the driver, number of tags, PLC type, network configuration, it is often not a problem to scan that fast.   However, if you have a large # of tags or are going to be having clients doing a lot of what we call in the OPC world "Synch Reads or Synch Writes", you have to be careful if you plan to have the Quick Client open, for all those subscription reads at 50ms have to yield time to the Synch Reads, and the more you subscriptions you have, the bigger the battle for who wins at 50 ms becomes.

 

It is for that reason that we suggest you to the following if you will have a project with a large # of tags and you have high performance expectations and plan to have the OPC Quick Client open at the same time as your HMI/SCADA system client or other client application:

  1. Start the Quick Client from the TOP Server and let it auto-connect to all your tags.
  2. Click File ⇒ Save in the Quick Client and give your configuration a file name.
  3. Click Tools ⇒ Options in the Quick Client and uncheck the box found there regarding Auto-creation of a project.  This will prevent the Quick Client from subscribing to all tags when launched in the future.
  4. Now back in your configuration, for each group of tags, in the left-hand window, right click on the group name and select Properties.
  5. Set the Group Update rate to a level that is more in keeping with your application requirements.  If your HMI/SCADA system is setup to ask for 1000 ms updates (1 sec), then setup the Quick Client for the same or close to the same rate. 
  6. Do this for each group in your configuration.
  7. Click File ⇒ Save in the Quick Client to save your configuration at this point.
  8. Optionally - if you do not need to monitor ALL the tags in the server, then delete the ones that you do not need to monitor, and save off your Quick Client config again.
  9. The next time you launch the Quick Client, it won't auto-subscribe to everything - click File ⇒ Open and open the file you saved in step 2 or 7 and the Quick Client will auto-connect with that particular configuration and update rate.

Using this methodology, you can create a variety of "test configs" in the OPC Quick Client for use in varying situations in your business.