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You can wire directly from a terminal outside a structure to a terminal inside the structure. LabVIEW creates a tunnel where the wire crosses the structure boundary. A tunnel allows data to flow in and out of loops and structures.

Wiring to Avoid

Avoid the following when wiring structures:

• Overlapping tunnels.
• Wiring from multiple frames of a Stacked Sequence structure.
• Failing to wire a tunnel in all cases of a Case structure.
• Assigning more than one value to a sequence local terminal.

For constants wired to structures, LabVIEW uses constant folding to optimize performance. With constant folding, LabVIEW stores constant values when it compiles VIs instead of calculating them at run time. You can display constant folding of structures by selecting Tools»Options, selecting Block Diagram from the Category list, and placing a checkmark in the Show constant folding of structures checkbox. When you place a checkmark in the Show constant folding of structures checkbox, gray hash marks appear inside structures that are wired to constants. The hash marks might not appear until after you run or save the VI.