Audio Input Express VI

LabVIEW 2015 myRIO Toolkit Help

Edition Date: June 2015

Part Number: 373925C-01

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Requires: myRIO Toolkit

Reads values from one or more audio input channels on the myRIO. Use this Express VI to read multiple samples for each channel at one time.

Details  

Dialog Box Options
Block Diagram Inputs
Block Diagram Outputs

Dialog Box Options

ParameterDescription
Node nameSpecifies the name of this Express VI. You can also double-click the name of this Express VI on the expandable node to edit the name.
ChannelSpecifies the audio input channel from which to read the value.
Custom channel nameSpecifies a custom name for the audio input channel that you select.
Delete ChannelDeletes the audio input channel that you select.
Add channelAdds a new audio input channel to the channel list. You can add up to two audio input channels.
Sample rateSpecifies the sampling frequency of the input signal. Valid values are between 1 kHz and 44.1 kHz. If you specify a frequency that is invalid, this Express VI coerces the specified value to the nearest valid value when you click the Validate button.
  • Frequency value—Specifies the value of the sampling frequency. The default is 1,000.
  • Frequency unit—Specifies the unit of the sampling frequency.
  • Validate—Validates whether this VI can generate the sampling frequency that you specify. If the specified sampling frequency is invalid, this Express VI coerces the specified value to the nearest valid value.
SamplesSpecifies the number of samples to read. The default is 1,000. Valid values must be greater than 0 and less than or equal to 10,000.
LatencyDisplays the latency between two adjacent signal generation iterations. Refer to the Details section of this topic for more information about latency.
View CodeDisplays the underlying code of this Express VI.
Connection DiagramShows the I/O connector pinouts on the myRIO or the roboRIO. The highlighted pinouts represent the channels that you configure.

Block Diagram Inputs

ParameterDescription
error in (no error)Describes error conditions that occur before this node runs.

Block Diagram Outputs

ParameterDescription
channel nameReturns the value that this Express VI reads from the audio input channel that you select, where channel name is the name of the audio input channel.
error outContains error information. This output provides standard error out functionality.

Audio Input Details

The following figure demonstrates the latency when you use the Audio Input Express VI to perform n samples read operations.

In the previous figure, the x-axis represents time and the y-axis represents amplitude. The waveform in blue represents the signal that the myRIO acquires. The red dotted line represents latency. When latency occurs, the myRIO does not acquire any signal. In other words, the time interval between two adjacent signal acquisition iterations is latency.

Related Information

Generating FPGA Clocks

Latency in N Samples Read and Write Operations

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