Working with graphs in SensDesk

16. 7. 2020

The SensDesk portal collects and visualizes measurements from HW group devices, such as Poseidon2, Damocles2, HWg-PWR, Ares (including LTE versions), SD-devices or NB-devices. In addition to basic functions, such as providing a concise overview of the states and current readings of detectors and sensors, graphs showing the history of the readings are also available. Graphs in SensDesk can be also used for additional analyses.

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In the SensDesk portal, graphs are shown in three places. First, there is a chart with measurements and Safe Range boundaries on the sensor details page. All connected sensors, grouped by the measured quantity, are plotted in a chart on the device details page. The third option is My Graph, where sensor and detector plots can be customized regardless of the measured quantities in order to compare them.

The graph area consists of several parts. At the top, there is a bar to set the chart properties. That is, what time range is plotted, what timezone is used, and what SD range is shown (individual sensor graphs only).

By default, a chart shows the last 7 days. For example, Wednesday to Wednesday or Saturday to Saturday. This default setting cannot be changed. However, the user can select another time interval – a day, a week, a month, or a custom interval.

In case of the pre-defined day, week and month intervals, the chart is scaled to show the entire interval. Therefore, if an unsuitable interval is selected (e.g. one month), it may happen that the chart appears incomplete. The two orange arrows change the interval. The fields for selecting specific dates are enabled only when the Custom interval is selected.

The Timezone field allows to specify the timezone to use for displaying time when hovering over a measured value. This can be important for monitoring the Safe Range and diagnosing problems. The default is UTC (Coordinated Universal Time), a globally unified time formerly called GMT (Greenwich Mean Time). The next option is by device; this means that the time settings in the device are used (only for future devices capable of working with real time, such as Poseidon2, Damocles2). The last option is by user, that is, the time zone is taken from the user’s profile (https://sensdesk.com/user).

When displaying the measured values, SensDesk can also indicate whether they fall within the Safe Range or not. Values outside of the Safe Range are plotted with a red line, other values with a green line. At the same time, the SafeRange is highlighted in green in the entire chart, so that it is immediately apparent whether or not the measured value is near the boundary. The SD range field allows toggling the displayed SafeRange between the SD range of the sensor and the Notice range used to work with Alarms (future use only – Notice Range is estimated to be available starting from Q3/2019). The SD range selection box is only available for individual sensor graphs.

Below the graph properties controls, there is a bar for switching among the displayed quantities (device details graphs only). It allows to quickly go from one measured value to another within one device to get a concise overview.

Below the bar, there is the actual graph that differs according to the page it is on. Missing values are indicated by a missing line. The start of an interval is indicated with an orange dot with a cross, so that even a short measurement outage is clearly visible.

The sensor details always show one value, which is either green (if inside the SafeRange) or red (if outside). The graph at the device details page can plot several sensors that measure the same quantity; in that case, different sensors are plotted with different colors. However, to avoid clutter, such a graph does not show the SafeRange because it can be different for each sensor. In a My Graph, each quantity has its own color and different sensors are distinguished by the line type (solid, dashed, dotted, and so on).

A legend describing the colors or line types is shown at the very bottom. By clicking a sensor in the legend, it is possible to exclude that sensor from a multi-value graph in order to simplify the view.

The Zoom function or the auxiliary timeline can be used to zoom into the measurements for a sensor or in a time interval. The auxiliary timeline only changes the displayed portion of the loaded data; the vertical axis scale is dynamically adjusted according to the actual displayed values.

The Zoom function allows to select a part of the range to see more details (it may need a little practice). The required portion is selected by clicking and dragging with the mouse. The Reset button in the upper right-hand corner of the graph cancels the selection.

Another useful feature is the ability to export graphs and measured values. The available options are accessed by clicking the “hamburger” icon in the upper right-hand corner of the graph.

The graph can be printed or exported to PNG, JPG, SVG or PDF.

The measured values in the displayed range can be exported to a CSV or XLS file for later processing, or displayed as a table directly in the browser.