Real-Time FIFO VIs

LabVIEW 2011 Embedded Module for ARM Microcontrollers Help

Edition Date: June 2011

Part Number: 372459E-01

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Requires: Embedded Module for ARM Microcontrollers or C Generator. This topic might not match its corresponding palette in LabVIEW depending on your operating system, licensed product(s), and target.

Use the Real-Time FIFO VIs to transfer data between VIs in an application. An RT FIFO acts like a fixed queue, where the first value you write to the FIFO is the first value that you can read from the FIFO.

RT FIFOs ensure deterministic behavior by imposing a size restriction on the data. You must define the number and size of the RT FIFO elements. Both a reader and writer can access the data in an RT FIFO at the same time, allowing RT FIFOs to work safely in a time-critical VI. You must ensure that you read data stored in an RT FIFO faster than you write data to the RT FIFO or at least before the queue fills to transfer every element without overwriting data. Because of the fixed-size restriction, an RT FIFO is a lossy form of communication.

Palette ObjectDescription
RTFIFOCreateCreates or obtains a reference to an RT FIFO. Use this reference when calling other Real-Time FIFO VIs. Wire data to the type input to determine the polymorphic instance to use or manually select the instance.
RTFIFODeleteDeletes the reference to a specified RT FIFO. You must manually select the polymorphic instance to use.
RTFIFOReadReads the oldest element in a RT FIFO. If there is no data in the RT FIFO, this VI returns the value of element. Wire data to the element input to determine the polymorphic instance to use or manually select the instance.
RTFIFOWriteWrites an element to an RT FIFO. Wire data to the element input to determine the polymorphic instance to use or manually select the instance.

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