Each Historic View has an Algorithm setting that allows you to associate the Historic View with one or more historic algorithms (calculations that are used to produce the values for the Historic View). For example, a Historic View can be configured to have an Average historic algorithm and a Sum historic algorithm. In the table of results produced for the Historic View, there will be an Average column that contains the average values that have been calculated for the Historic View and a Sum column that contains the sum total values that have been calculated for the Historic View.
Geo SCADA Expert supports many of the algorithms that are defined in the OPC Historical Data Access specification and you can also use your own ‘custom’ historic algorithms.
Take care with End and End Last Historic Algorithms used on clients, or with Geo SCADA Expert features, that run in Local Time with Daylight Saving Time. Ensure that the start and end times specified for the sample interval do not coincide exactly with the time at which the clock jumps backward. Include a small offset in the sample time, to offset the calculation to avoid the sample end or start time exactly matching the time that the clock jumps backward at the transition from Daylight Saving Time to Standard Time. A small offset of 1s or even 1ms should suffice. For more information about Daylight Saving Time, see The Effects of Daylight Saving Time Adjustments.
Further Information
Built-in historic algorithms: see Built-In Historic Algorithms for Processed Historic Data.
Custom historic algorithms: see Historic Algorithms (Custom).