Understanding and Resolving Event Table Display Limits in PI Vision

If you have ever found that your PI Vision Event Table isn't showing the full list of expected Event Frames (EFs), you're not alone. This is a common challenge for many PI Vision users, especially when working with large volumes of event data. In this post, we'll explore why this happens and how you can configure PI Vision to show all your events.

The Default Event Frame Limit in PI Vision

By default, PI Vision applies a limit to the number of Event Frames retrieved and displayed in the Event Table symbol. Typically, this limit is set to 100 results to optimize performance and prevent overwhelming users with too much data at once.

This means that even if your data set contains hundreds or thousands of Event Frames, only the first 100 (based on your search criteria) will display unless you modify the configuration.

Changing the Event Frame Limit

To display more than the default number of events, a PI Vision server administrator can adjust the relevant parameter in the web.config file on the PI Vision server. Be aware:

• This change affects all users of the PI Vision application.
• Increasing the limit significantly could impact performance, especially if many users are querying large data sets at once.

Steps to update the limit:

1. Locate the web.config file on your PI Vision web server.
2. Find the setting that specifies the maximum number of Event Frames to return (often under EventFrameSearchMaxResults).
3. Adjust the value as required (for example, set it to 500 or another appropriate limit).
4. Save the file and restart the PI Vision application (or IIS) to apply the change.

Always make a backup of the web.config file before making changes.

"Load More" Behavior and the Role of Table Scrolling

In addition to the server-side limit, PI Vision's Event Table employs a lazy-loading mechanism—it loads a subset of events (typically 25 at a time) and loads more as the user scrolls down.

If the Event Table is sized such that all initially loaded events fit on the screen (i.e., there's no scroll bar), the "load more" functionality may not trigger, leading to the appearance that no further events are available.

Quick Tip

If you're not seeing all your events and suspect this may be the cause:

• Enter Edit Mode in PI Vision.
• Reduce the height of the Event Table symbol until a scroll bar appears.
• Save and view the display; as you scroll, more events should load dynamically.

Final Recommendations

• Check the configured maximum event limit in the web.config file if you anticipate needing to see more events than the default allows.
• Adjust the Event Table height to ensure lazy loading of additional events isn't inadvertently disabled by showing all rows at once.
• Keep performance in mind when increasing search result limits or loading many events.

Understanding these configuration nuances can save you and your users a lot of time and help ensure the data you need is always at your fingertips in PI Vision.

Have you encountered similar event table issues or have tips to share? Leave a comment below!