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How to

How to


Products: Automation Server, AS-B, Enterprise Server, AS-P, WorkStation, Virtual Project Servers
Functionalities: Trends
Product version: 1.9
12/14/2016

Attaching a Calculation Method to a Trend Chart Series

You attach a calculation method to a trend chart series to process the recorded values and present the result.

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​Use a calculation method to process the records of the trend log before presenting them in a trend log list or a trend chart. The original records in the trend log are not affected by the calculation method. The calculation method is applied to the trend log records grouped by a specific time interval.

The following calculation methods are available:

  • None

  • Maximum

  • Minimum

  • Average

  • Sum

  • Delta

  • Delta over period

  • Meter consumption

Note:

  • Adapt the period so it contains the required amount of records to generate a correct calculation.

  • If a calculation method is connected to an interval trend log with delta, make sure that the period and delta are adapted for the calculation.

None

No calculation is performed. The actual values are presented.

Maximum

The maximum value of each period is presented.

 
action_zoom_plus_stroke Maximum calculation method, schematic
Figure: Maximum calculation method, schematic
Important:

If the log point is offline or no value is produced during the interval, no value is displayed.

Minimum

The minimum value of each period is presented.

 
action_zoom_plus_stroke Minimum calculation method, schematic
Figure: Minimum calculation method, schematic
Important:

If the log point is offline or no value is produced during the interval, no value is displayed.

Average

The average of the values in each period is calculated and presented.

 
action_zoom_plus_stroke Average calculation method, schematic
Figure: Average calculation method, schematic
Important:

If the log point is offline or no value is produced during the interval, no value is displayed.

Sum

The sum of the values in each period is calculated and presented.

 
action_zoom_plus_stroke Sum calculation method, schematic
Figure: Sum calculation method, schematic

Delta

The change to the previous value is calculated and presented.

 
action_zoom_plus_stroke Delta calculation method, schematic
Figure: Delta calculation method, schematic

Delta over Period

The change over a period is calculated and presented. The value at the period limit is often interpolated, based upon the last value in the old period and the first value in the new period.

 
action_zoom_plus_stroke Delta over period calculation method, schematic
Figure: Delta over period calculation method, schematic

Meter Consumption

Meter consumption is a delta over period calculation with meter functionality. For more information, see Meter Trend Logs .

Period Timestamps in Trend Charts and Trend Log Lists

When a calculated value for a period is presented, the middle of the period is used as the timestamp.

Example:

The calculated value for the period 8:00-9:00 is stamped 8:30. If there is a value at 9:01, the next period is 9:00-10:00, which is stamped as 9:30. The full period may not have passed yet, but the value can be presented even if parts of the period are in the future.

To attach a calculation method to a trend chart series

  1. In WorkStation, in the System Tree pane, select the trend chart you want to attach a calculation method to.

  2. On the Trend Chart toolbar, click Open trend chart settings button

     
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    .

  3. Click the Calculations tab.

  4. In the Data series box, select the series you want to add a calculation method to.

     
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  5. In the Calculation method box, select a calculation method.

  6. Select Delta over period if the calculation method is a delta calculation with periods.

  7. In the Period box, select the time span for which the calculation method is to be executed.

    Note:

    • If Custom is selected in the Period box, enter a custom time span for which the calculation method is to be executed in the Custom period box and the time when you want the custom period to start in the Custom period alignment boxes.

    • To calculate the required number of records for a trend log, multiply the number of records in one day with the number of days you want the trend log to record. For example, the interval of the trend log is set to 1 hour, then this gives 24 recorded values per day. The trend log should record at least one month of recorded values equal to 31 days. For example, the number of records = 24 x 31 = 744.

  8. In the Custom period box, enter a custom time span for which the calculation method is to be executed.

  9. In the Custom period alignment boxes, enter the time when you want the custom period to start.

  10. Click OK .

A calculation method is now attached to the series.

See Also

  • Calculation Methods
  • Trend Chart Settings Dialog Box – Calculation Tab
  • Meter Trend Log Calculation Fails