Feedback Node
Stores a data value from one VI or loop execution to the next. A Feedback Node is analogous to a z^-1 block in feedback control theory and digital signal processing.
The Feedback Node uses the value wired to the initializer terminal as the initial value for the first iteration or execution. The Feedback Node then stores the previous iteration result for each subsequent execution. If you do not wire a value to the initializer terminal, the Feedback Node uses the default value for the data type and continues building on previous results in subsequent executions.
The node automatically appears when you wire the output of a subVI, function, or group of subVIs or functions to the input of that same VI, function, or group. In loops, you can right-click the Feedback Node and select Replace with Shift Register from the shortcut menu to replace the Feedback Node with shift registers. You also can replace shift registers with a Feedback Node. Both the Feedback Node and shift registers are analogous to the z-1 block in feedback control theory and digital signal processing.
Example
Refer to the Feedback Node - Build Array VI in the labview\examples\general\structs.llb for an example of using the Feedback Node.