Show live data

A trend can be configured to show live data. Live data is data that is retrieved continuously in real time for a fixed duration that is relative to the current time (for example, the last hour).

When retrieving live data, the Trend application retrieves data incrementally with every update. For example, if you set the update rate to ten seconds, then every ten seconds, the Trend application retrieves data for the last ten seconds and updates the chart with that data. Additionally, it periodically retrieves data for the entire chart time span to refresh the entire chart. You can specify both the update rate and the refresh interval for the entire chart. For more information, see Configuring General Properties.

If the connection to the Historian is lost while retrieving live data, any data that was retrieved up to that point is still shown on the chart until the next full refresh occurs. If the Historian is still unavailable at that time, the old data is cleared from the trend chart.

Notes: When retrieving live data, the time stamp rule for data retrieval is forced to "End." For more information on this setting, see Timestamp Rule (wwTimestampRule).

While the chart is displaying live data, if the trended data includes points outside of the visible plot area, any affected tags are automatically scaled to fit.

To display "live" data

1. Click the Update to Current Time toolbar button so that it is highlighted.

2. In the Duration list of the Time toolbar, click a duration or type one manually.

3. Click the Live Mode toolbar button.

To display "static" data

• Click the Stop Live Mode toolbar button.