Read (FIFO Method)

Requires: FPGA Module

Reads the oldest element in an FPGA FIFO and removes the element from the FIFO.

Use the FIFO Method Node to implement this method.

Details  

	FIFO In specifies the FIFO. If you leave FIFO In unwired, you can specify the FIFO by right-clicking the FIFO Method Node and selecting a FIFO from the shortcut menu. Otherwise, you can wire a FIFO control, FIFO constant, VI-Defined FIFO Configuration node, or another FIFO Method node to FIFO In.
	Timeout specifies the number of clock ticks the function waits for available data in the FIFO if the FIFO is empty. A value of –1 prevents the function from timing out, so the function completes execution only when data is available for reading. A value of 0 indicates that the function does not wait. Wire a constant of 0 to Timeout if you use the FIFO Method Node in a single-cycle Timed Loop.
	FIFO Out returns FIFO In if FIFO In is wired. Otherwise, FIFO Out returns the FIFO that you specify in the FIFO Method Node.
	Element returns the oldest data element in the FIFO. The Element data type is the data type you configure in the FIFO Properties dialog box when you create the FIFO. If the FIFO is empty, Element is undefined.
	Timed Out? returns TRUE if an element is not available in the FIFO before the function completes execution. If Timed Out? is TRUE, Element is undefined.

Read (FIFO Method) Details

You can use this method and DMA FIFOs to receive data from host VIs.

Special Considerations for Single-Cycle Timed Loops

If you use the FIFO Method Node configured with the Read method in a single-cycle Timed Loop, you must set the Read option in the Advanced Code Generation FIFO Properties page to Arbitrate if Multiple Requestors Only or Never Arbitrate for the FIFO item you read, and you cannot use the function with that FIFO anywhere else in the FPGA VI. You also must wire a constant of 0 to Timeout.

You can use FIFOs to transfer data among multiple clock domains.