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DAQmx Read (Multiple Samples) (G Dataflow)

Last Modified: February 6, 2017

Reads one or more floating-point samples from one or more counter tasks. Use an instance that reads a floating-point value when NI-DAQmx scales counter samples to a floating-point value.

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task in

task in is the name of the task that the operation applies.

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number of samples per channel

number of samples per channel specifies the number of samples to read.

If you leave this input unwired or set it to -1, NI-DAQmx determines how many samples to read based on if the task acquires samples continuously or acquires a finite number of samples.

If the task acquires samples continuously and you set this input to -1, this node reads all the samples currently available in the buffer.

If the task acquires a finite number of samples and you set this input to -1, the node waits for the task to acquire all requested samples, then reads those samples. If you set the Read All Available Samples property to TRUE, the node reads the samples currently available in the buffer and does not wait for the task to acquire all requested samples.

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timeout

timeout specifies the amount of time in seconds to wait for samples to become available. If the time elapses, the node returns an error and any samples read before the timeout elapsed. The default timeout is 10 seconds. If you set timeout to -1, the node waits indefinitely.

If you set timeout to 0, the node tries once to read the requested samples and returns an error if it is unable to.

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error in

error in describes error conditions that occur before this node runs. This input provides standard 'error in' functionality.

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task out

task out is a reference to the task after this node runs.

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data

data returns a 2D array of samples. Each row corresponds to a channel in the task. Each column corresponds to a sample from each channel. The order of the channels in the array corresponds to the order in which you add the channels to the task or to the order of the channels you specify with the Channels to Read property.

NI-DAQmx scales the data to the units of the measurement, including any custom scaling you apply to the channels. Use the DAQmx Create Virtual Channel node or the DAQ Assistant to specify these units.

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error out

error out contains error information. If error in indicates that an error occurred before this node ran, error out contains the same error information. Otherwise, error out describes the error status that this node produces.

Where This Node Can Run:

Desktop OS: Windows

FPGA: LabVIEW NXG does not support FPGA devices


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