Some points and accumulators measure a value over a period of time and then record their value at the end of each time period. Such a value is known as an End of Period value (End of Period is sometimes abbreviated to EOP). An End of Period value might be used, for example, to provide a daily total or a weekly average.
The types of point or accumulator that measure a value over a period of time include counter, runtime, minimum, maximum, and mean.
After recording their value at the end of a time period, some types of point and accumulator then reset their value automatically, ready for the start of the next time period. This is known as an End of Period Reset. The reset value is specific to the type of point or accumulator and is fixed, rather than user-definable. Counters, for example, typically reset to zero, whereas minimum, maximum, and mean points and accumulators might reset to their source point’s value.
Where points reset to zero ClearSCADA records the value when the reset occurs and then records the zero value one millisecond later. The zero is recorded whether or not the value is recorded by the outstation.
Example of reset historic data
Some types of point or accumulator support the ability to have their value initialized to either a fixed or user-definable value (depending on the type of point or accumulator). For information about initializing point values, see Initialize in the ClearSCADA Guide to Drivers. For accumulator-related information, see Initialize in the ClearSCADA Guide to Core Configuration.