Managing Breakpoints

Use the Breakpoint tool to place a breakpoint on a VI, node, or wire and pause execution at that location. When you set a breakpoint on a wire, execution pauses after data passes through the wire and the Pause button appears red. Place a breakpoint on the block diagram to pause execution after all nodes on the block diagram execute. The block diagram border appears red and blinks to reflect the placement of a breakpoint.

Note  (MathScript RT Module) You also can set a breakpoint on a line of script in a MathScript Node.

When a VI pauses at a breakpoint, LabVIEW brings the block diagram to the front and uses a marquee to highlight the node or wire that contains the breakpoint. When you move the cursor over an existing breakpoint, the black area of the Breakpoint tool cursor appears white.

Setting Breakpoints

Complete the following steps to place a breakpoint on a VI, node, or wire and pause execution at that location.

1. Use the Breakpoint tool to click the VI, node, or wire where you want to pause execution. You also can right-click the VI, node, or wire and select Breakpoint»Set Breakpoint from the shortcut menu.

Note  (MathScript RT Module) You cannot place breakpoints on certain lines of script in MathScript Nodes. For example, you cannot place a breakpoint on the line a = 1;. If you try to place a breakpoint on a line of script that does not support breakpoints, LabVIEW automatically moves the breakpoint to the next line that supports breakpoints.

2. Run the VI. When you reach a breakpoint during execution, the VI pauses and the Pause button appears red. Also, the VI background and border begin blinking. You can take the following actions:
   • Single-step through execution using the single-stepping buttons.
   • Check intermediate values on probes that you placed on wires prior to running the VI.
   • Check intermediate values on probes that you place after running the VI if you have enabled the Retain Wire Values option.
   • Change values of front panel controls.
   • Check the Call list pull-down menu to see the list of VIs that call the VI that is stopped at a breakpoint.
   • Click the Pause button to continue running to the next breakpoint or until the VI finishes running.

Disabling and Enabling Breakpoints

To disable a breakpoint so the VI continues executing when LabVIEW reaches the breakpoint, right-click an object with a breakpoint and select Breakpoint»Disable Breakpoint from the shortcut menu. To enable a breakpoint that you previously disabled, right-click the block diagram object and select Breakpoint»Enable Breakpoint from the shortcut menu. You also can disable or enable breakpoints individually or all at once using the Breakpoint Manager window.

Removing Breakpoints

Use the Breakpoint tool to click an existing breakpoint to remove it. You also can right-click a breakpoint using the Positioning tool and select Breakpoint»Clear Breakpoint from the shortcut menu to remove it. To remove all breakpoints in the VI hierarchy, select Edit»Remove Breakpoints from Hierarchy. You also can remove all breakpoints in the VI hierarchy using the Breakpoint Manager window.

You must manually remove breakpoints in dynamically called VIs or VIs referenced by the Static VI Reference function.

Note  (MathScript RT Module) To remove all breakpoints in a script in a MathScript Node, right-click inside the MathScript Node and select Clear Script Breakpoints from the shortcut menu.

To locate and manage all breakpoints in the VI hierarchy, select View»Breakpoint Manager. Double-click any item in the listbox to highlight the breakpoint on the block diagram.

Note  You cannot view breakpoints on a password-protected block diagram if you do not know the password, but you can enable, disable, and remove breakpoints. After you run the VI, the VI will return to the state it was in before you made any changes to the breakpoints.