Fetches binary I/Q data inside a data value reference from a single record in an acquisition.

Note You must call Delete Data Value Reference on any outstanding data value references before calling niRFSA Fetch IQ, niRFSA Close, niRFSA Initialize, or niRFSA Reset. Refer to the LabVIEW Help for more information on the Delete Data Value Reference function and data value references.

Supported Devices: PXIe-5820/5830/5831/5832/5840/5841/5842/5860


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Inputs/Outputs

  • ci64.png record to fetch —

    record to fetch specifies the record to retrieve. Record numbers are zero-based. The default value is 0.

  • civrn.png instrument handle —

    instrument handle identifies your instrument session. instrument handle is obtained from the niRFSA Initialize VI or the niRFSA Initialize With Options VI.

  • ci64.png samples to read (-1) —

    samples to read specifies the number of samples to fetch. A value of -1 specifies that NI-RFSA fetches all samples. The default value is -1.

    Note Setting samples to read to –1 fetches all remaining samples currently available depending on the Fetch Relative To property and the Fetch Offset property settings.
  • cdbl.png timeout (10 sec) —

    timeout specifies the time, in seconds, allotted for the VI to complete before returning a timeout error. A value of -1 specifies that the VI waits until all data is available. The default value is 10 seconds.

  • cerrcodeclst.png error in —

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

  • iivrn.png instrument handle out —

    instrument handle out passes a reference to your instrument session to the next VI. instrument handle is obtained from the niRFSA Initialize VI or the niRFSA Initialize With Options VI and identifies a particular instrument session.

  • idatavalref.png data value reference —

    returns the external data value reference containing the acquired unscaled, complex waveform. The array is composed of interleaved I and Q samples, where the order of the array is as follows:

    Array[0] = I(0)

    Array[1] = Q(0)

    Array[2] = I(1)

    Array[3] = Q(1)

  • inclst.png wfm info —

    wfm info contains the absolute and relative timestamps for the operation, the time interval, and the actual number of samples read.

  • idbl.png absolute timestamp —

    absolute timestamp returns the timestamp, in seconds, of the first fetched sample that is comparable between records and acquisitions.

    Note The value of the absolute timestamp returned is always 0 for the PXIe-5820/5830/5831/5832/5840/5841/5842/5860.
  • idbl.png relative timestamp —

    relative timestamp returns a timestamp that corresponds to the difference, in seconds, between the first sample returned and the Reference Trigger location. The timestamp is zero if the Reference Trigger has not occurred.

  • idbl.png dt —

    dt returns the time interval between data points in the acquired signal. The I/Q data sample rate is the reciprocal of this value.

  • ii64.png actual samples read —

    actual samples read returns an integer representing the number of samples in the waveform.

  • idbl.png offset —

    offset returns the offset to scale data, (b), in mx + b form.

  • idbl.png gain —

    gain returns the gain to scale data, (m), in mx + b form.

  • idbl.png reserved1 —

  • idbl.png reserved2 —

  • ierrcodeclst.png error out —

    error out contains error information. This output provides standard error out functionality.

    • Details

    Use the In Place Element structure Data Value Reference Read/Write Element to read data and operate on the data within place. Refer to the LabVIEW Help for more information on the Data Value Reference Read/Write Element.

    To improve streaming performance, consider the following recommendations:

    • Use LabVIEW (64-bit).
    • Set the Host DMA Buffer Size property to at least 512 MB.
    • Use the TDMS Advanced Asynchronous Write (Data Ref) function to optimize performance when writing data to disk. Refer to the LabVIEW Help for more information about this function.