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Single-Point Versus Waveform Acquisition

Last Modified: June 10, 2021

Specify if an Analog Input (AI) channel performs single-point or waveform acquisitions when you add the channel to a system definition.

In single-point acquisitions, channels acquire a single point at a time and return the value directly to the system. A single-point acquisition is an immediate, non-buffered operation that occurs at the rate at which the system runs.

In waveform acquisitions, channels acquire signals over a period of time as waveforms.

The following table displays the use case for each acquisition type.

Acquisition Type Use Case
Single-Point Useful for implementing closed-loop control, as the system reads one value per iteration of the Primary Control Loop and can produce appropriate outputs during the same iteration.

Useful for reading data at a rate faster than the rate a system runs.

For example, when you need to monitor or log a value that changes quickly, such as the pressure in an engine cylinder, acquiring the signal as a waveform allows you to achieve the high sampling rate required to represent the signal adequately.

When you configure AI channels to perform waveform acquisitions, you can achieve rates up to the maximum sampling rate for the DAQ device without being restricted by the system rate.

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