RT FIFO Create

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Updated2023-02-17
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RT FIFO Create

Creates an RT FIFO or obtains a reference to an existing RT FIFO that you can use with other RT FIFO nodes.

Inputs/Outputs

elements in array

The number of elements in the array for each RT FIFO element.

This input only applies if the RT FIFO elements are arrays. RT FIFOs do not support multi-dimensional arrays.

Default value: 1

size

The number of elements in the RT FIFO.

Default value: 10

name

The name of the RT FIFO that you want to obtain or create.

Default value: Empty string

type

Defines the type of data that you want the RT FIFO to contain. RT FIFOs do not support data types of variable size, such as clusters, strings, and variants. RT FIFOs also do not support multi-dimensional arrays.

Waveform Data Transfer with RT FIFOs

If you use an RT FIFO to transfer waveform data, the attributes of the waveform do not transfer. The attributes element of a waveform is a variant, which is variable-sized and therefore incompatible with the RT FIFO.

create if not found?

A Boolean that determines whether to create a new RT FIFO if the FIFO specified by name does not currently exist.

True	The node creates a new RT FIFO if the FIFO specified by name does not exist.
False	The node does not create a new RT FIFO and returns an error if the FIFO specified by name does not exist.

Default value: True

error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Default value: No error

datapoints in waveform

The number of datapoints for every element of the array of waveforms. This input only applies if the RT FIFO elements are waveforms.

Default value: 1

r/w modes

Read and write modes for a new RT FIFO. The read and write modes define the behavior of an RT FIFO that reads a value from an empty RT FIFO or writes a value to an RT FIFO that does not have an empty slot.

You can specify one of the following modes for reads and writes:

polling—Optimizes the throughput performance of read and write operations by continually polling the RT FIFO for new data or an open slot. The polling mode responds quicker than the blocking mode to new data or new empty slots, but requires more CPU overhead. Use timeout in ms of RT FIFO Read or RT FIFO Write to specify the amount of time that a write operation should poll for an empty slot or a read operation should poll for new data.

blocking—Optimizes the utilization of the CPU during read and write operations by allowing the thread of the VI to sleep while it waits, allowing other tasks in the system to execute. Use timeout in ms of RT FIFO Read or RT FIFO Write to specify an amount of time that a read operation can wait for a new value or a write operation can wait for an empty slot.

If you use RT FIFO Create to return a reference to an existing RT FIFO, the reference uses the read and write modes of the existing RT FIFO and ignores the modes specified with r/w modes.