Maximizing FactoryTalk View Site Edition Performance

DMC recently helped a client maximize the visual performance and response of a FactoryTalk View Site Edition (FTV SE) Local Station application talking to a Micro850 PLC, and we have some tips and tricks to share for getting the most out of your FTV SE applications!

Our application had some lag when loading new screens because of the large amount of tags required to populate the screens. FTV SE can pull up to about 200 tags from a Micro 850 per second; with larger PLC programs taking more time to send tags.

For smaller HMI/PLC applications, all of the PLC tags from a Micro 850 can easily be pulled quickly while loading a screen. For larger applications, there may be some delay after opening a screen before all of the tags on a screen are loaded from the PLC and ready to populate their indicators.

However, FactoryTalk lets you load screens snappily, even when talking to smaller PLCs or when large amounts of data need to be loaded.

A few tips and tricks are below!

1. Decrease Maximum Tag Update Rate (per Screen) - This rate controls the shortest possible time it will take the FactoryTalk application to acquire or send a tag. This is important for buttons and indicators that need to have a fast response, as well as for loading screens quickly.
   1. To access this setting, right-click on a screen, select Display Settings, and under the Properties window, select the drop-down for Maximum Tag Update Rate. The default setting is 1 second; this may appear slow for most applications. A rate of 0.25 or 0.1 seconds will usually allow the screen to react without visible lag.
      
   2. This may have different levels of impact with different PLC platforms - this should be a good solution for fast performance with the Logix line of processors. We found that additional steps were needed with the smaller Micro800 line.
   3. Keep in mind that your application may not be able to keep up with faster Tag Update Rate setpoints. This is dependent on the number of tags you have on the screen and the number of tags that are being fetched in the background (read on to learn more about background fetching!)
2. Add Screen Caching - FactoryTalk View Site Edition's default behavior is to close any screens that aren't actively being displayed. This minimizes PC resource usage and allows you to edit screens in an active application (one of my favorite features). However, you can individually configure each screen to be cached, so that the screen is kept in memory even when it isn't shown on the screen. This greatly improves behavior for laggy screens.
   1. To access this setting, right-click on a screen, select Display Settings, and under the Properties window, choose Yes for Cache After Displaying.
   2. You also have the option to select whether the screen is Always Updating or not. Always Updating is a good selection for screens that don't populate immediately even when cached - we found this was the best choice for most of our larger screens with lots of tags. Keep in mind that if the screen is Always Updating, it will always be polling tags from the PLC. This may influence the update rate of tags on other screens in your application.
      
3. Add Screen Pre-Caching - If Screen Caching improved your application's performance, you may also want to consider Pre-Caching your screens! Pre-Caching pre-loads the screens while the application is starting up, without displaying them on the PC. Cached screens without pre-caching may still be slow to load the first time they're displayed; pre-caching makes the display pull from an already cached screen the first time that it's loaded.
   1. This can be done via a Startup Macro. Create a macro in the Explorer pane under Logic and Control > Macros. Right-click to create a New Macro.
      
   2. In the Macro editor, add a call to the "Display" function for each screen that you'd like to precache. Use the \Z flag to cache a screen without marking it as Always Updating. Use the \ZA flag to cache a screen and set the screen to Always Update. (A full description of this function and possible flags is available in the FTV help files as "FactoryTalk View Site Edition Help > FactoryTalk View commands > Graphics commands > Display")
      
   3. When launching or creating your FTV SE Client with the FactoryTalk View SE Client Wizard, include your macro as the Startup Macro.
      

If you follow these tips, you should have a fast and snappy HMI!

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