To automatically concatenate an array leaving a loop, wire the array directly to the loop output tunnel, right-click the tunnel, and select Tunnel Mode»Concatenating from the shortcut menu. Selecting Concatenating appends all inputs in order, forming an output array of the same dimension as the array input wired. Additional tunnel modes include Last Value and Indexing. Last Value displays the last value from the last loop iteration. Indexing builds an array of higher dimension. You can change when LabVIEW writes values to the loop output tunnel based on a condition.
Refer to the Loop Tunnel Modes VI in the labview\examples\Structures\Shift Registers and Tunnels directory for an example of automatically concatenating arrays.