About set (Fallback) action

If a writable point has a null or invalid value at inputs In1-In16 (this means that both override levels are currently configured for automatic update), the priority scan sets the Out slot to the value of the Fallback property.

By default, an operator-level user can change the Fallback property, by right-clicking on the point and clicking Actions > Set . This shows a window that displays the current Fallback value.

Figure 1. Set action prompt to change writable point’s Fallback property

From the set action prompt, a Cancel leaves the current Fallback property unchanged. Otherwise, the Fallback property is set to the value entered (or currently displayed value).

Note: The set action does not display (or accept) a null value for Fallback. However, a Fallback of null can be entered on the point’s Property Sheet.

A common application for this feature is with numeric writables used as setpoints, particularly under a NiagaraNetwork. As proxy points are always read-only points (not writable points), yet they inherit any actions from the source point, this feature provides user access to setpoints via Px graphics without creating additional proxy points. In particular, this set action works well with SetPoint type widgets found in the kitPx palette. For related details, see the Niagara Graphics Guide.

Each of the four constant kitControl components also provides a set action that works in a similar manner, including with kitPx widgets. However, a constant object (NumericConst, BooleanConst, etc.), has no priority inputs or Fallback property. The set action simply writes directly to the component’s current Out slot. For details, see the Niagara KitControl Guide.