Fetches I/Q data from a single record in an acquisition.

Syntax

ViStatus _VI_FUNC niRFSA_FetchIqSingleRecordComplexF64(ViSession vi, ViConstString channelList, ViInt64 recordNumber, ViInt64 numberOfSamples, ViReal64 timeout, ni complex number f64 *data, niRFSA_wfmInfo *wfmInfo)

Remarks

The fetch transfers acquired waveform data from device memory to computer memory. The data was acquired to onboard memory previously by the hardware after the acquisition was initiated.

This function is not necessary if you use the niRFSA_ReadIqSingleRecordComplexF64 function because the niRFSA_ReadIqSingleRecordComplexF64 function performs the fetch as part of the function.

Supported Devices: PXIe-5644/5645/5646, PXI-5661, PXIe-5663/5663E/5665/5667/5668, PXIe-5820/5830/5831/5832/5840/5841/5842/5860

Related Topics

None (Trigger Type)

Parameters

NameDirectionTypeDescription
vi[in]ViSession

Identifies your instrument session. vi is obtained from the niRFSA_Init or niRFSA_InitWithOptions function.

channelList[in]ViConstString

Identifies which channels to apply settings. Specify an empty string as the value of this parameter.

recordNumber[in]ViInt64

Specifies the record to retrieve. Record numbers are zero-based.

numberOfSamples[in]ViInt64

Specifies the number of samples to fetch. The value must specify the array size of the data parameter.

timeout[in]ViReal64

PXI-5661, PXIe-5663/5665/5667 Specifies the time, in seconds, allotted for the function to complete before returning a timeout error.

PXIe-5644/5645/5646, PXIe-5668, PXIe-5820/5830/5831/5832/5840/5841/5842/5860 Specifies the time, in seconds, allotted to receive the reference trigger.

For all supported devices, a value of specifies the function waits until all data is available. A value of 0 specifies the function immediately returns available data.

data[out]ni complex number f64 *

Returns the acquired waveform. Allocate an NIComplexNumber array at least as large as numberOfSamples.

wfmInfo[out]niRFSA_wfmInfo *

Contains the absolute and relative timestamps for the operation, the time interval (dt), and the actual number of samples read.

The following list provides more information about each of these properties:

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

The value of the absolute timestamp returned is always 0 for the PXIe-5644/5645/5646, PXIe-5668, and PXIe-5820/5830/5831/5832/5840/5841/5842/5860.

  • 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.

The value of the relative timestamp returned is always 0 for the PXIe-5644/5645/5646.

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

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

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

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

Returns

Returns the status code of this operation. The status code either indicates success or describes an error or warning condition. Examine the status code from each call to an NI-RFSA function to determine if an error has occurred. To obtain a text description of the status code and additional information about the error condition, call the niRFSA_GetError function. To clear the error information from NI-RFSA, call the niRFSA_ClearError function. The general meaning of the status code is as follows:

Value

Meaning

0

Success

Positive Values

Warnings

Negative Values

Errors