Potentiometer

About 5 min read

TwPotentiometer · Category: Basic

Locked look

From 2.11.0 the Potentiometer is dimmed and shows the lock when Read Only is bound to a tag whose value is true or the user lacks the permission. If a Lock Reason is set, tapping the locked knob shows it. A potentiometer whose Setpoint is not bound to a tag only displays a value and keeps its normal look. See Locked controls.

Settings

These settings are in the properties panel on the right while the widget is selected, mostly in the Potentiometer Settings section. The default value is the value the widget has when it is first added to a page.

Value

Setting	Type	Default	Description
Setpoint (Process Value) processValue	Number	0	Setpoint. Bind it to the Tag that receives the value; the knob writes it there. Without a binding this is the value shown in the editor.
Feedback Value feedbackValue	Number	—	Optional actual value. When bound, the knob and readout show this value and a small marker shows the setpoint.
Min Value minValue	Number	0	Value at the start of the scale. The written value never goes below it.
Step step	Number	1	The value snaps to multiples of this step, counted from Min Value. 0 or empty means continuous.
Unit unit	Text	—	Unit shown after the value, e.g. %, bar or rpm.
Max Value maxValue	Number	100	Value at the end of the scale. The written value never goes above it.
Decimals decimals	Number	0	Number of decimal places shown and written (0 to 6).
Unit from Tag unitFromTag	Checkbox	Off	Shows the unit from the tag definition of the Feedback Value binding, else of the Setpoint binding (Direct), instead of Unit. On a shared modal it follows the modal's tag prefix. Unit is used when the tag has no unit and in the Editor. Only a plain tag name or a single quoted tag qualifies; a calculated expression such as 'Flow' / 1000 keeps Unit.

Behavior

Setting	Type	Default	Description
Read Only readOnly	Checkbox	Off	When on, the potentiometer only shows the value and cannot be turned at runtime.
Lock Reason lockReason	Text	—	Optional. While the knob is locked at runtime (Read Only bound to a tag that is true, or a user without write permission), a tap shows this text briefly instead of the permission message, and it appears as the tooltip. Example: "Interlock: door open". A locale key is translated. Empty keeps the default behaviour.
Write Mode writeMode	Selection	onRelease	On release writes only the final value. While turning also writes intermediate values, at most once per write interval. A cancelled turn (Escape, lost pointer) writes the start value back. Options: onRelease On release, throttled While turning (throttled)
Mouse Wheel wheelEnabled	Checkbox	Off	Allows changing the value with the mouse wheel, one step per notch. The value is written after a short pause.
Needs Confirmation needsConfirmation	Checkbox	Off	Asks once per turn (drag, key press or wheel pause) before the final value is written. Intermediate values are never written.
Write Interval (ms) throttleInterval	Number	250	Minimum time between intermediate writes in the While turning mode (100 to 5000 ms).

Scale

Setting	Type	Default	Description
Start Angle startAngle	Number	-135	Knob angle of Min Value in degrees; 0 points up and positive values turn clockwise (default -135).
Major Ticks majorTicks	Number	6	Number of labelled major ticks including both ends (2 to 21).
Show Scale Labels showScaleLabels	Checkbox	On	Shows the values next to the major ticks.
Scale Label Size scaleLabelSize	Number	15	Font size of the scale labels, 10–28 (default 15). Labels scale with the widget; raise the value to keep them readable on a small widget. With many major ticks, large values can make the labels overlap.
Sweep Angle sweepAngle	Number	270	Clockwise angle from Min Value to Max Value in degrees (30 to 340, default 270).
Minor Ticks minorTicks	Number	4	Number of small ticks between two major ticks (0 to 9).
Show Value showValue	Checkbox	On	Shows the current value with its unit below the knob.
Value Size readoutSize	Number	26	Font size of the value readout, 14–34 (default 26). Long values are compressed to fit below the dial.

Appearance

Setting	Type	Default	Description
Caption caption	Text	—	Text shown at the bottom of the potentiometer. Long captions are compressed to fit.
Caption Style labelStyle	Text	—	Extra CSS for the caption, e.g. fill: #c00; font-size: 18px.
Caption Size captionSize	Number	15	Font size of the caption, 10–24 (default 15). A larger caption moves the value readout up. A font-size in Caption Style overrides it.
Accent Color accentColor	Color	—	Color of the value arc, setpoint marker and focus ring. Leave empty to use the theme accent.

Other settings

Setting	Type	Default	Description
Enable Flashing enableFlashing	Checkbox	Off	Makes the widget blink (an opacity pulse every second). Usually bound to an alarm condition.
Log Button logButton	Checkbox	Off	At runtime shows a chart icon when hovering the widget; clicking it adds the Tags bound to the widget to the log Tag list.

Bindings

In the Bindings (Rules) section of the properties panel, a Tag can be bound to the following properties of this widget with a Direct binding. The binding types (Direct, IntRange, FloatRange, Boolean, Bit) are the same for all widgets; they are described on the Widget Reference page.

title, visible, authorization, x, y, width, height, rotation, class, foregroundColor, backgroundColor, borderColor, borderStyle, borderWidth, borderRadius, borderTopLeftRadius, borderTopRightRadius, enableFlashing, logButton, lockReason, processValue, feedbackValue, minValue, maxValue, step, decimals, unit, unitFromTag, startAngle, sweepAngle, majorTicks, minorTicks, showScaleLabels, scaleLabelSize, readoutSize, captionSize, showValue, writeMode, throttleInterval, wheelEnabled, needsConfirmation, readOnly, caption, accentColor

The style fields of the widget can also be bound as style.<field> (e.g. style.left, style.top).

Common sections

While this widget is selected, the properties panel also shows these common sections: General, Layout, Appearance, Bindings (Rules). These sections are described on the Page Editor page.