You can configure a VI to retain wire values on the diagram so that when you create a probe, the probe displays the most recent data that flowed through the wire at the last VI execution.
Retaining wire values can help you debug a VI when a diagram is complex and you need to view specific wire data after a VI finishes executing to determine where an error occurred.
Click the Retain wire values button on the document toolbar to start retaining all wire values on the diagram.
Run the VI at least once so that wire values are immediately available to any probes you create.
Place a probe on a specific wire by right-clicking the wire and selecting Add probe. To see the most recent value of the data that passed through the wire, either hover over the wire or click the probe.