ErgoTechWiki

com.ergotech.vib.graphics.Knob

The Knob graphic is a Basic Layout slider and knob graphic used to select or display a numeric value.

Knob is an Active Graphic that can also be used as an Active Control. At runtime, a user can move the dial pointer to select a new numeric value.

Knob can also be updated from a data source or logic connection so it displays the current value from another source.

• Selecting a numeric value
• Displaying a numeric value
• Creating a dial-style input control
• Setting a process value or setpoint
• Sending a selected value into application logic
• Showing the current value from a connected server or data source

Knob accepts a value object that can be converted to a number.

The input value updates the displayed knob position. This is useful when the Knob needs to show the current value from a server, data source, calculation, or another logic component.

Knob can send an output value when the user changes the dial position.

The selected value is sent through PrimaryOutPort.

Knob is a dial-style control with configurable scale, pointer, tick marks, colors, and numeric range.

Knob-specific settings may include:

• High Value Sets the maximum value for the knob range.
• Low Value Sets the minimum value for the knob range.
• Color for Knob Sets the color of the knob body.
• Color for Pointer Sets the color of the pointer.
• Color for Tic Marks Sets the color of the tick marks.
• Color for Ring Sets the color of the outer ring highlight.
• Nubs, Number Of Sets the number of ridges drawn on the knob.
• Nub Size Sets the nub size as a percentage of the knob radius.
• Radius Sets the size of the knob body as a percentage of the component bounds.
• Snap To Controls the value increment the knob snaps to.
• Send Intermediate Values Controls whether intermediate values are sent while the knob is being moved.
• Use Color Controls whether incoming color data is used, if supported.

Knob includes scale and tick mark settings similar to meter graphics.

Knob angle example showing how Angle Starting and Angle Ending define the scale range around the knob.

Scale and tick settings may include:

• Angle Starting Sets where the knob scale starts.
• Angle Ending Sets where the knob scale ends.
• Center X Percent Controls the horizontal placement of the knob and scale.
• Center Y Percent Controls the vertical placement of the knob and scale.
• Tic Format String Controls the number format used for tick labels.
• Tic Length Sets the tick mark length.
• Tic Spacing Sets the value spacing between tick marks.
• Tics per Label Sets how often tick marks are labeled.

Knob pointer settings may include:

• Pointer Distance Controls how far from the center the pointer is drawn.
• Pointer Radius Controls the size of the pointer.

In the Logic Editor, Knob may include:

• PrimaryOutPort
• updateDisplayedValue

The PrimaryOutPort sends the selected value.

The updateDisplayedValue port updates the displayed knob value from another source.

Knob is commonly used to set a value on a server or data source while also displaying the current value from that source.

When using Knob with a server value, it is often useful to connect the server back to the Knob so the Knob display stays updated with the current server value.

For stable value updates, avoid sending low-quality or transitional values through the connector when possible.

For related numeric display behavior, see Meters.

• MIStudio Design Editor
• Basic Layout
• Sliders and Knobs
• Slider
• SliderSingleScale
• SliderDoubleScale
• SliderImage
• Meters
• Active Graphic