Linking data points to cells

Report generation sequence from the data viewpoint

When a report is generated, a query will be sent to the WinCC OA archive database (based on the structure and data point list that has been transferred manually).

The set of values addressed in the query (already compressed) will be returned to the Excel program and processed there further on the basis of the link parameters (programmed in macros). Statistical analysis of data point values over time can be included in the reporting process.

For instance, the following can be performed in Excel:

• Calculation of two-hourly values from a set of values, that is, inserting extra compression levels (if for instance WinCC OA only calculates one-hourly values, daily values, and so on).

• Exclusion of correction values from mean value calculations on a set of values (that is, not included in calculation). (Crossing-out numbers in Excel tables is only formatting and these numbers are still included as (cell) values in a normal mean-value calculation with an Excel formula).

Designing and configuring a worksheet

The link between the cells (of each column in the data area) and the data point values is specified in the template file using Add data point or Edit data point. You also define here what statistical calculations (functions,such as Min, Max) should be included.

The resultant set of values and the calculation results are finally displayed as Excel worksheets, charts or both. The formatting of the results is defined in the template file.

Formulae need only be entered in the formatted data rows in the template. They are then automatically repeated as many times as is necessary for the set of values retrieved.

The history value in detail

W hat data point attributes can you retrieve?

• The value of a data point for a particular time period. For instance, hourly values, daily values, monthly values, depending on the AC type that has been set (only compressed values for AC types).

• Descriptions such as comment lines (in each project language),

• Status bits.

Where do the history values come from?

The history data is archived and stored online during operation of the facility in accordance with AC configuration (see Vision module/Archiving Compression/AC Configuration panel and the figure in Example of Use case 2).

Statistical calculations (config "_dp_fct") can be incorporated in the history value before archiving (see compression levels and AC types).

Feedback of process data

The archive data is not just held for report purposes, but can also provide a useful source for calculating future setpoint values for an installation. The main function of the report is to present data from the archive (History DB) in a user-friendly format and in accordance with standards.