NI-DAQmx .NET Framework 4.0 API Reference

CounterSingleChannelReader.BeginMemoryOptimizedReadMultiSampleDouble Method (Int32, AsyncCallback, Object, Double[])

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Updated2023-02-21
2 minute(s) read

Begins an asynchronous memory-optimized read of one or more Double samples from a single CIChannel in a task.

Namespace: NationalInstruments.DAQmx
Assembly: NationalInstruments.DAQmx (in NationalInstruments.DAQmx.dll) Version: 20.7.40.49302

Syntax

public IAsyncResult BeginMemoryOptimizedReadMultiSampleDouble(
	int numberOfSamples,
	AsyncCallback callback,
	Object state,
	double[] data
)

Public Function BeginMemoryOptimizedReadMultiSampleDouble ( 
	numberOfSamples As Integer,
	callback As AsyncCallback,
	state As Object,
	data As Double()
) As IAsyncResult

Parameters

numberOfSamples: Type: SystemInt32
The number of samples to read. If you set numberOfSamples to -1 for a continuous acquisition, the read retrieves all samples available in the buffer at the time of the read. If you set numberOfSamples to -1 for a finite acquisition, the read behavior is set by the ReadAllAvailableSamples property of the DaqStream you are reading from.
callback: Type: SystemAsyncCallback
An optional asynchronous callback that is called when the read is complete. Specify if you do not want a callback when the read is complete.
state: Type: SystemObject
A user-provided object that distinguishes this asynchronous read request from other requests. Use this parameter to provide information to the callback. Specify if you do not need to pass any additional information to the callback.
data: Type: SystemDouble
An initialized 1D array of Double samples that contains the read data. Each element in the array corresponds to a sample from the channel.

Return Value

Type: IAsyncResult
An IAsyncResult that represents the asynchronous call.

Remarks

If the data buffer is large enough to hold the number of samples requested, this overload attempts to reuse existing memory allocated from the array to acquire data. This results in more efficient memory allocation when performing multiple reads with a continuous counter input task. The memory allocation for the buffer is available to a maximum of 2 GB.

To get the read data or any exceptions that occurred during an asynchronous read initiated with this method, call EndMemoryOptimizedReadMultiSampleDouble(IAsyncResult, Int32) with the returned IAsyncResult.

NI-DAQmx scales the returned data to the units of the measurement, including any custom scaling you apply to the channel. You specify these units with the create channel methods or the DAQ Assistant.

NI-DAQmx read and write methods time out after the amount of time specified by the Timeout property on the task you are reading from or writing to.

Refer to NI-DAQmx Readers and Writers for more information about memory limitations in NI-DAQmx read methods.

NI-DAQmx .NET Framework 4.0 API Reference

Table of Contents

CounterSingleChannelReader.BeginMemoryOptimizedReadMultiSampleDouble Method (Int32, AsyncCallback, Object, Double[])

Syntax

Parameters

Return Value

Remarks

See Also

Reference

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