The Value Indicator is a CygNet-aware analog control that adds visual context to real-time point and alarm data. A data range is represented on a vertical bar that fills the control between an upper and lower bound. The source of the lower value bound and upper value bound can be either hard-coded to an explicit value, or dynamically determined for each facility by sourcing the value from an attribute of the associated point (using an Indexed field, General data field, Minimum setpoint value (analog only) or Maximum setpoint value (analog only)). A value indicator on a templated screen supports different bounds for each source facility. By using a point attribute to store the bounds (for example, Indexed 1 for the lower value bound and Indexed 2 for the upper value bound), you can have a templated screen without having to script the control. Any configured alarm limits for the associated point are indicated on the bar and an animated marker on the left side points to the current value. Several other configurable properties are supported, including:
- The control can display a static text string, such as a label, or a dynamic text string based on point or facility attributes. Dynamic text is built using tokens, which can represent real-time CVS point properties, point configuration properties, and facility properties. In run mode, the tokens are replaced with the attribute's value.
- The control's color elements can be set to one of the following options: a) automatically follow the selected application theme regardless of the underlying color palette used, b) sourced from the point state color defined for the associated point, or c) be explicitly configured. The alarm limit range can optionally be configured to display point state color.
- Colors displayed in the control can be overridden when a custom color palette is selected for the screen.
- Font sizing, text styling, and text weighting are also configurable.
- Date, time, and value formatting for the text displayed on the control is supported.
- The control can be hidden if the associated point is invalid.
- This control supports tooltips, which can be displayed as tokenized text, a Canvas object, or the tooltip can be scripted to retrieve and display values for related points or CygNet notes.
- A context menu is available at runtime with access to CygNet point and alarm data, including alarm acknowledgment, current and history values, point and facility configuration, and trending point data on a default chart. Custom context menu items can be scripted allowing customized control behavior.
Value Indicator Example
The following image shows a value indicator control.
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A value indicator control showing Casing Pressure in high alarm, |
Property Inheritance
Property Inheritance
Property inheritance is a widely used concept in Canvas. The application supports an explicit relationship between screens, objects, and controls, where certain property values, such as SiteService and facility tags, are passed from one element to another via an inheritance framework. Screens, objects, and controls can be configured as property senders or property receivers and provide configuration options where you can explicitly define the source of the SiteService and facility. Depending on how you have your screens, objects, and controls set up, the SiteService and facility may come from any one of the following sources:
- from itself — indicated by selecting <Self> and then explicitly configuring the property
- inherited from the screen — indicated by selecting Screen, which is always present as a sender
- inherited from another control — indicated by selecting the Name of the sending control
Broadcasting
Screens and objects support an additional notification option to broadcast their SiteService and facility selection changes to other open screens running in the Canvas or Canvas View application. If configured, a <Broadcast> option is available to source the screen's SiteService and facility properties from another open screen.
For example, a text tool can be configured to get its facility from the screen and the screen can be configured to get its facility from a tag chooser. Or Screen_A might source its facility from Screen_B, which gets its facility from a tag chooser.
Receiver or Sender
The Value Indicator control supports property inheritance as a receiver of its SiteService and facility:
| Receive from | Send to | ||
|---|---|---|---|
| SiteService | Facility | SiteService | Facility |
| self screen |
self screen other controls |
none | none |
The Value Indicator control does not send its SiteService or facility to other controls.
