DigitalSingleChannelReader.BeginReadWaveform Method (Int32, AsyncCallback, Object)
- Updated2023-02-21
- 2 minute(s) read
DigitalSingleChannelReaderBeginReadWaveform Method (Int32, AsyncCallback, Object)
Begins an asynchronous read of one or more digital waveform samples from a single DIChannel in a task.
Namespace: NationalInstruments.DAQmx
Assembly: NationalInstruments.DAQmx (in NationalInstruments.DAQmx.dll) Version: 20.7.40.49302
Syntax
public IAsyncResult BeginReadWaveform( int numberOfSamples, AsyncCallback callback, Object state )
Public Function BeginReadWaveform ( numberOfSamples As Integer, callback As AsyncCallback, state As Object ) 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.
Return Value
Type: IAsyncResultAn IAsyncResult that represents the asynchronous call.
Remarks
To get the read data or any exceptions that occurred during an asynchronous read initiated with BeginReadWaveform(Int32, AsyncCallback, Object), call EndReadWaveform(IAsyncResult) with the returned IAsyncResult.
The data returned from digital waveform reads is affected by the WaveformAttributeMode property of the DaqStream you are reading from.
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.
 Note |
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| Refer to Asynchronous Reads and Writes for additional information. |