The Trends application allows you to work with trends that are recurring samples of data. In order to view the Trends application, you must have Show rights. Any change in the application rights is applicable only after a re-login or refresh.
Trends are of two types, online and offline.
Online Trending: In case of online trending, the trend data are uploaded continuously to the management station and are not saved in the automation station. Online trends record real-time values from your plant and display them graphically in a Trend View. The data values are sent to the Trends application upon each change of value. In case of online trending, an uninterrupted site connection with the management station is required. The measured values can be irretrievably lost when the site is interrupted during data recording. Therefore, online trend is not well-suited for long-term secure data recording. They can be used for real-time visualization of one or more process variables, usually for analysis or diagnosis purpose.
Offline Trends: In the case of offline trending, the trend data is saved locally to the trendlog object in the automation station and thereafter, uploaded to the management station either automatically or manually. The offline trend data is recorded and saved by the trendlog objects even when the management station is not connected. The automatic and manual transfer to the management station is done in the following situations:
Automatic:
- When the number of defined entries is reached
- When the maximum buffer size is reached
Manual:
- When the data transfer is triggered by a user in the management station
The precision for a 64 bit value is supported till 2E49 (15 digits). GmsBitString64 data type is not supported.
Trends in the Flex Client allow you to view trend charts, search for trend objects, start and pause trend data display, create and modify a trend view definition, define the Settings, delete a trend view definition and an online trend log object, and view quality information and missing data.
This section provides background information on Trends in the Flex Client. For procedures or workflows, see the step-by-step section.
Trends Workspace – Tile View
Trends are located in the Application View under Applications > Trends.
In System Browser:
- When you select Trends, the Trend tab displays all the related trend objects such as offline trends, online trends, and trend view definitions in a tile view.
- When you select a particular sub folder, the Trend tab displays all objects present in that sub folder.
You can add new trends or search for existing trends from the tile view.
On clicking 
, the Settings menu displays from which you can access the Trend Settings dialog box. This dialog box provides options to define the settings which are applied to online trend log objects, offline trend log objects and trend view definitions.
Trend Settings
The Trend Settings dialog box allows you to define the settings, which are applied to online trend log objects, offline trend log objects and trend view definitions. In case of trend view definitions, these settings are applied only during creation of new trend view definitions.
NOTE:
Trend settings are saved per user and display the user-specific settings.
1 | Data Accuracy | Displays the number of samples per series, based on the selection anywhere between Loading Fast to High Resolution. By default, the number of samples saved is 100. |
2 | Default time period | Allows to specify the time range, for which the trend data displays in the Trend View. |
3 | Data status indication | Select Enable to display the quality indication area of rectangle shape on the Trend View. The area is highlighted with red color, in order to indicate a quality issue (a problem with the data point). |
Trends Workspace – View Mode
The view mode allows you to view the complete chart preview of the selected trend view definition, online or offline trend log objects.
1 | Legend | Displays information on the objects present in the trend view definition. You can specify the type of information to be displayed by clicking the Layout Setting Depending on the selected Text Representation the following type of object information displays in the legend: |
button on the Horizontal Navigation Bar (see Horizontal Navigation Bar in 2 |
| Behaves as a toggle button and stops trend logging when you click |
.3 | Edit | Displays the trends workspace in the Edit mode. |
4 | Zoom mode | Displays the chart data in the zoom mode for the selected time interval. See Zooming Data in Trends Step-by-Step. |
5 |
| Displays the following options: |
6 | Pre-defined time ranges | Displays the trend series according to the selected time range. |
Trends Workspace – Edit Mode
The Edit mode allows you to modify the properties of the selected trend view definition, online or offline trend log object.
1 | Legend | Displays information on the objects present in the trend view definition. You can specify the type of information to be displayed by clicking the Layout Setting Depending on the selected Text Representation the following type of object information displays in the legend: |
2 |
| Behaves as a toggle button and stops trend logging when you select |
3 |
| Displays the following options: |
4 | Options | Allows you to modify properties, such as trend name or time period, for which you want the data to reflect in the chart, chart properties, and so on. See Options Properties for additional information. |
5 | Series | Allows you to add new data points and modify the look and feel of the chart. See Series Properties for additional information. |
6 | Save | Saves the selected trend view definition. If you add new data points to an online or offline trend log object, then a new trend view definition is created. |
7 |
| Provides options to save the trend view definition with a new name or discard the changes. |
Options Properties
Allows you to modify properties such as the trend name, the time period for which you want the data to reflect in the chart, chart properties, and so on.
1 | Trend name | Allows you to enter the name for a trend view definition, which is stored as a description. |
2 | Default time period | Allows you to specify the time range, for which the trend data should display in the Trend View. |
3 | SubChart [n] | Displays the sub chart added to the trend view definition. |
4 | Left Y-Axis | Allows you to specify the Max, Min range for the left y-axis, which is displayed in the Trend View. Auto scaling: Shows the scale of the y-axis, based on the trend series data. A minimum and maximum range must be defined if auto-scaling is disabled. |
5 | Right Y-Axis | Allows you to specify the Max, Min range for the right y-axis, which is displayed in the Trend View. Auto scaling: Shows the scale of the y-axis, based on the trend series data. A minimum and maximum range must be defined if auto-scaling is disabled. |
Series Properties
Allows you to modify properties, corresponding to the individual trend series of a trend view definition.
1 | Add datapoint | Displays the Select Data Point dialog box that allows you to add one or more data points. |
2 |
| Provides options to add and remove sub charts. |
3 | Style | Allows you to select the appropriate style properties like Color, Width, Dash Type, Marker, and Smoothing for each trend series. See Style Properties for more information. |
4 | Data Point | Displays the description of the data point. You can also enter a name for trend series in the text box below, which is stored as a description in the current language of the user. |
5 | Y-Axis | Indicates the y-axis where the data point is scaled (left or right). |
6 |
| Allows you to remove the trend series from the trend view definition only. |
7 |
| Displays the properties of either a trended object or a trendlog object in the contextual pane below the Properties tab, on the appropriate selection. If you reduce the size of the Series tab, the Delete option Select Property: Displays the Select Property dialog box that allows you to select the appropriate data point property. The changes are reflected immediately in the TVD on changing the property. The Select Property option displays only if the data point has more than one property. Move to: Allows you to move the data points within sub charts. You can move a binary or multistate point to another sub chart, only if the point is not present in the other chart. In case of analog points, you can only move analog points of the same unit to other charts. The unit of analog points in the source and destination sub charts has to be identical. For example, you can move an analog point with degree Celsius as the Unit from Sub Chart 1 to Sub Chart 2, only if Sub Chart 2 has analog points with degree Celsius as the unit and there are less than 5 sub points in Sub Chart 2. Information: Displays the object information such as description, name, alias, device associated with, path, and so on. The object information also displays, when you select the object in the System Browser and select the information icon |
in Properties.
Style Properties | |
Color |
|
Width |
|
Dash Type |
|
Marker |
|
Smoothing | ON/OFF |
Subcharts
You can have multiple charts added to the main chart of your trend view definition using Subcharts. This concept allows you to distribute the trend series with different units and with different data points across multiple charts rather than overloading the main chart. It also allows you to have a look at the multiple trend series in a common view thereby improving the readability of chart data.
Following are the features of Subcharts:
- For all Subcharts, a single time bar displays. If you change the default time period in the Edit mode, then the same time is reflected for all the Subcharts in the View mode.
- When you zoom in or zoom out a particular area of any Subchart, then the result of the zoom operation is applicable to all the Subcharts in the trend view definition.
- When you select any of the following options (hour, day, month, year, all) on the predefined time ranges in the View mode, the selected option is applied to all Subcharts present in trend view definition.
- When you hide all the trend series, the Subcharts do not display any data and the time bar is hidden.
- When you delete a data point from a particular Subchart, then the data point is removed from that Subchart only and not from any other Subchart. Similarly, when you add a data point to a particular Subchart, then the data point is allocated to that specific Subchart only.
- You can add the below data points in one subchart considering following criteria:
- For selection of data points in one subchart, select either one of the input value (analog or binary or multistate).
- Maximum 10 analog input points of same unit.
- 2 axis (left and right together) with 1 unit value per axis for example ℃ or ℉.
- 1 multistate input point
- 1 binary input point
- For example, assume that you have created a Subchart and selected the following combination of data points and trend log objects:
- 2 analog inputs with same unit (℃)
- 2 analog inputs with same unit (℉)
- 1 analog input with same unit (%)
- 1 multistate input
- 1 binary input
- Consider the above example, the number of sub charts and their points will be as follows:
- Subchart 1 – 2 analog input points with ℃ as unit and 2 analog input points with ℉ as unit. This is because 1 Subchart can have a maximum 2 axis (left axis with one input value and right axis with another input value).
- Subchart 2 – 1 analog input point with % as unit requires other Subchart as the unit of analog input is different and you can have only two different units in 1 Subchart.
- Subchart 3 – 1 multistate input point.
- Subchart 4 – 1 binary input point.
Quality Attributes
The Trend View can display a number of state attributes, referred to as quality attributes, along with the trend data. These enable you to identify problems with the data point being recorded and assist with the diagnosis of plant conditions. The quality attributes display as a tooltip when you position your mouse pointer over a trend series. Only the highest priority displays in the Trend View if several states are active. In order to display the quality attributes, you must ensure that the Show Quality option for the series to which you want to view the quality information is selected in the management station. The Trend View also displays a quality indication area of rectangle shape, which is highlighted with the red color in order to indicate a quality issue (a problem with the data point).
The following is a list of the quality attributes:
Item | Name | Description |
| Error logging data | Error reading data value from the monitored object |
| Reliability fault | Indicates that the value of the Trendlog object is no longer reliable. |
| Faulty | Indicates that a data point error exists in the Trendlog object (values may not be usable for follow-on evaluation) |
| Overridden | Indicates that the data point on a module is overridden. |
| Out of service | Indicates that the Out of Service property is switched on. |
| Log Enabled/Disabled | Indicates that the Trendlog object is enabled. |
| Log interrupted | Indicates that the automation station has been set to state Log_interrupted in the trend buffer (for example: in the event of a power outage, application program stop, change of data point log type). This may cause trend data from not being logged. |
| Buffer purged | Indicates that the buffer in the Trendlog object is deleted. |
| Buffer full | Indicates that the Trendlog buffer is full. |
| Time shift | Indicates that the time in the automation station was changed. |
| Connected/Disconnected | Indicates that no connection exists to the logged data point. |
| Reduced data | Indicates that the logged data may be huge and needs to be reduced before displaying. |
| Added/Modified data | Indicates that the data has been added or modified manually. |
