IviScope_FetchWaveformMeasurement
IviScopeWaveformMeas Capability Group
C Function Prototype
ViStatus IviScope_FetchWaveformMeasurement (ViSession vi, ViConstString channel ViInt32 measFunction, ViReal64 *measurement);
Purpose
This function fetches a specified waveform measurement from a specific channel from a previously initiated waveform acquisition. You can specify a particular measurement type, such as rise time, frequency, and voltage peak-to-peak. The waveform on which the oscilloscope calculates the waveform measurement is from an acquisition that was previously initiated.
Use the IviScope_InitiateAcquisition function to start an acquisition on the channels that were enabled with the IviScope_ConfigureChannel function. The oscilloscope acquires waveforms for the enabled channels concurrently. Use the IviScope_AcquisitionStatus function to determine when the acquisition is complete. Call this function separately for each waveform measurement on a specific channel.
You can call the IviScope_ReadWaveformMeasurement function instead of the IviScope_InitiateAcquisition function. The IviScope_ReadWaveformMeasurement function starts an acquisition on all enabled channels. It then waits for the acquisition to complete, obtains a waveform measurement on the specified channel, and returns the measurement value. Call this function separately to obtain any other waveform measurements on a specific channel.
Configure the appropriate reference levels before calling this function to take a rise time, fall time, width negative, width positive, duty cycle negative, or duty cycle positive measurement.
You can configure the low, mid, and high references either by calling the IviScope_ConfigureRefLevels function or by setting the following attributes:
This function does not check the instrument status. Typically, you call this function only in a sequence of calls to other low-level driver functions. The sequence performs one operation. Use the low-level functions to optimize one or more aspects of interaction with the instrument. Call the IviScope_error_query function at the conclusion of the sequence to check the instrument status.
Parameters
| Inputs | Type | Description |
| vi | ViSession | The instrument handle that you obtain from the IviScope_init or IviScope_InitWithOptions functions. The handle identifies a particular IVI session. |
| channel | ViString | Name of the channel from which to read a waveform. |
| measFunction | ViInt32 | Characteristic of the acquired waveform to be measured. Defined values |
| Outputs | Type | Description |
| measurement | ViReal64 | The measured value. |