Specify the Period over which an Accumulator’s Value is Calculated

Use the fields within the End of Period Reset section of the Reset tab to specify the period over which an Accumulator’s value is calculated. Use the Continuous check box at the top of the Reset tab to specify whether End of Period Resets still occur when an Accumulator has no new data to process (see Specify whether an Accumulator Continuously Sends Timed Reports and Resets its Value).

• Interval—Use this field to specify the duration over which an Accumulator’s value is calculated. Enter the required interval in the OPC Time Format. You can enter the value directly in the field, or use the Interval window (accessed via the field's browse button) to specify the required value. For example, enter 1H for ClearSCADA to calculate an Accumulator’s value over a one-hour period.Once the period elapses, the Accumulator value is reset to zero, following which it increments once more until the next interval elapses.
• Offset—Use this field to specify the start of the first calculation period. Enter the required offset in the OPC Relative Time Format. You can enter the value directly in the field, or use the Offset window (accessed via the field's browse button) to specify the required value. For example, enter D + 15M to start calculating the Accumulator’s value from 00:15hrs each day, and thereafter at the intervals specified in the Interval field, above.

  NOTE: To disable End of Period resets, set the Interval to 0 (zero)—ClearSCADA will ignore any value specified in the Offset field (you can clear the Offset field if required).

• Local Time—ClearSCADA can calculate the End of Period Reset time on a Local or System time basis.

  Select this check box for ClearSCADA to calculate the End of Period Reset using Local Time, for example Eastern Standard Time (EST) if the local time zone is that for the East coast of America. Use the Daylight Saving Time check box (see below) to specify whether to take into account any daylight saving adjustments.

  Ensure that the Local Time check box is clear for ClearSCADA to calculate the End of Period Reset using Coordinated Universal Time (UTC). This is the time that regulates the operation of your system. For more information, see Time Zone Support in ClearSCADA.

• Daylight Saving Time—Applicable if the Local Time check box is selected (see above). Select this check box for ClearSCADA to automatically adjust the time to account for Daylight Saving Time (DST).

  Ensure that the Daylight Saving Time check box is clear if ClearSCADA is not to make any DST time adjustments.

  Be aware that, depending on the driver on which an Accumulator’s source is located, there may be gaps in the data when the clocks are adjusted forwards, or missing data when times repeat after the clocks are adjusted back to account for DST. Ensure that the Daylight Saving Time check box is clear if such gaps are not acceptable on your system.