Using the Probe Tool

Use the Probe tool to check intermediate values on a wire as a VI runs. Use the Probe tool if you have a complicated block diagram with a series of operations, any one of which might return incorrect data. Use the Probe tool with execution highlighting, single-stepping, and breakpoints to determine if and where data are incorrect. If data are available, the probe immediately updates during single-stepping or when you pause at a breakpoint. When execution pauses at a node because of single-stepping or a breakpoint, you also can probe the wire that just executed to see the value that flowed through that wire.

You also can create custom probes to specify which indicator you use to view the probed data. For example, if you are viewing numeric data, you can choose to see that data in a chart within the probe.

Complete the following steps to use the Probe tool.

1. Use the Probe tool to click a wire. A floating Probe window appears. LabVIEW numbers the Probe window automatically and assigns the same number to the corresponding wire. No data is visible in the Probe window until you run the VI.
   
   You also can right-click a wire and select Probe from the shortcut menu to display the floating Probe window.
   
2. Place more probes on other wires and objects in the VI where you expect the data to change. Drag the Probe window out of the way if necessary.
3. Run the VI. The Probe window displays data passed along the wire.
4. Compare the data that appears in the Probe windows to what you expected.
5. Close the Probe window to remove the probe. Probes close automatically when you close the block diagram.

You cannot use the Probe window to change data. The probe has no effect on the way a VI runs.

There are three options available when you right-click the Probe window:

• Find Wire—Finds the associated wire. LabVIEW brings the block diagram that contains that wire to the front and highlights the wire.
• Reinitialize to Default—Resets the value displayed the Probe window displays to its default value.
• Copy Data—Copies the data to other numeric controls in the same VI or in other VIs.