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Graph report with statistics on process data
When operators study graphs to get an overview of process components’ behavior, to detect adverse trends and to see what happened in the process before and after an intervention or incident, it can be useful to also get statistics on the process data displayed in the graph.
The operator can generate a graph report for a user defined period with statistics for the selected graph signals, calculated by the IGSS system, for all graph types except an Embedded Graph Basic. It is also possible to include an image of the graph itself. Graph reports can be created for all objects relevant for graphs: Analog, digital, counter and table objects.
Generate a graph report
- In the graph, click the Report icon in the graph’s toolbar – or if this is not available, typically in an embedded graph, right-click inside the graph area and select Generate Report….
- In the Graph Report dialog, you can either keep the suggested period (the same as defined for the graph itself), or change the report period (and the graph itself) by clicking the Current: button. This will open the Period tab of the Graph Properties form, where you can define another period.
- Select the Graph box, if you want to include an image of the graph in the report. If zoom is used, the zoom window will be included in the graph image unless it is manually hidden.
- Under Report includes, select which object signals and values or state changes (digital objects) to include. Double-click the Yes (default) to toggle between Yes and No:
- For Analog, Counter and Table objects, select the relevant statistics values e.g. Minimum, Maximum and Average values plus Change, Sum and Standard deviation. These options correspond to the data reduction methods that can be selected in the Object Properties form’s Data Management tab. Which values it makes sense to calculate and include in the report depends on the actual object (process component). Including Sum could e.g. be relevant for flow measurements, Change for counting operational hours and Standard deviation to determine if everything is operating correctly.
For Digital objects, define if both State changes and Time active shall be included.
- Click Generate to create the graph report.
If you have zoomed in on an area of the graph, the graph report will be generated based on this specific period, which will be displayed on the button. Example: 13-03-2020 10:59:39 -> 13-03-2020 11:10:14.
View the graph report
The graph report displays separate statistics and other information for each object signal. For all object types the following information is shown:
- The start and end date and time of the graph period in dd-MM-yyyy HH:mm:ss, and the total graph period in HH:mm:ss is shown at the top.
- The total number of data points from which measurement statistics are calculated.
- Under each table it says if the data period is complete i.e. if it was possible to log data for the entire period. If not, and the graph has periods with no data, it says Incomplete data and shows the total period of missing data in HH: mm:ss.
- The data and time, the graph report was generated.
- (If selected) An image of the graph for the selected period including zoom window, graph values and data points, if these were defined for the graph.
For Analog, Counter and Table objects, the following statistics are shown:
- Statistical values for the selected data reductions e.g. the maximum and average values, measured during the complete period displayed in the relevant unit e.g. m3/h.
- Next to the Maximum and Minimum values, the date and time, these occurred, is shown.
- The Average value is calculated on the basis of the sum of the measured values divided by the actual period, where data was available. In some cases the sum value does not really make sense, depending on what is measured in which type of units.
- The Change value is the difference between the first and the last values measured in the period. Start and end values are shown to the right. This information can be relevant when counting operational hours.
- The Standard deviation shows how much the signal deviates from the average value. Such information can be relevant to determine if things run smoothly. The calculation of the standard deviation is weighted against the value changes in the log files, not against time, and is an estimate of the difference between the signal values in the graph area and the average value.
- The sum of the measured values during the total graph period. Calculating the sum makes sense for things measured per sec, per hour or per minute like e.g. for flow (liter/sec) to determine the total flow for the defined period. For other types of measurements, the sum does not make sense and is therefore displayed with the value 0.
For Digital objects, the following statistics are shown for each object:
- Top states: Shows up to 10 object states in which the digital object was registered most frequently during the graph period. If the digital object signal has more than 10 states, an additional line with show for much time the object was in other states.
- Time Active: The total time listed as HH:mm:ss (hours:minutes:seconds) and hours (e.g. 1,57) the object was in this state.
- The percentage of the total operational time in this state during the graph period.
The order of the date format will follow the Windows data format selected for the individual operator pc.
Where to find graph reports
The graph report is first generated as preview in HTML format and opens in the pc’s default Internet browser, which will typically offer additional opportunities such as:
- Save the graph report as an image in .png or HTML format with a user defined name in a user defined folder on the pc.
- Print the graph report on the default printer, or save in .pdf format.
- Other browser specific options.
The graph report is automatically placed in a subfolder called GraphReports in the operator pc’s TEMP folder with the name graphreport_dd-MM-yyyy. Example: file:///C:/Users/ari/AppData/Local/Temp/GraphReports/graphreport_16-03-2020145306.html
Change report format and add company logo
The GraphReports folder also contains a style sheet, graphstyle.css, which is created the first time a graph report is generated. Here, the system designer can change the report fonts etc. and add a company logo.
The style sheet will have to be changed on each local operator pc.
If the user defined style sheet is deleted from the GraphReport folder, the default IGSS style sheet will automatically be created the next time a graph is generated.
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