IviDmm_FetchMultiPoint
IviDmmMultipoint Capability Group
C Function Prototype
ViStatus IviDmm_FetchMultiPoint(ViSession vi, ViInt32 maxTime, ViInt32 arraySize, ViReal64 readingArray[], ViInt32 *actualPts);
Purpose
This function returns an array of values from a previously-initiated multipoint measurement. The number of measurements the DMM takes is determined by Trigger Count and Sample Count. Call the IviDmm_Initiate function to initiate a measurement before calling this function.
After this function executes, each element in the readingArray parameter is an actual reading or a value indicating that an overrange condition occurred. If an overrange condition occurs, the corresponding readingArray element contains an IEEE defined NaN (Not a Number) value and the function returns IVIDMM_WARN_OVER_RANGE. Test each element in the readingArray parameter for overrange with the IviDmm_IsOverRange function.
In most instrument classes, there is a programmatic way to determine when a measurement has completed and data is available. Therefore, a maxTime parameter is not needed in the IviDmm_Fetch function for these classes. This is not true for the majority of DMMs. The maxTime parameter specifies how long to wait in the IviDmm_FetchMultiPoint operation because it is possible that no data is available or the trigger event did not occur.
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. You use the low-level functions to optimize one or more aspects of interaction with the instrument. To check the instrument status, call the IviDmm_error_query function at the conclusion of the sequence.
Parameters
| Inputs | Type | Description | ||
| vi | ViSession | The instrument handle that you obtain from the IviDmm_init or IviDmm_InitWithOptions functions. The handle identifies a particular IVI session. | ||
| maxTime | ViInt32 | Pass the maximum length of time in milliseconds to allow the multipoint fetch operation to complete. If the operation does not complete within this time interval, the function returns the IVIDMM_ERROR_MAX_TIME_EXCEEDED error. When this occurs, you can call IviDmm_Abort to cancel the multipoint fetch operation and return the instrument to the Idle state.
Defined Values: IVIDMM_VAL_MAX_TIME_INFINITE—Wait indefinitely for a timeout. IVIDMM_VAL_MAX_TIME_IMMEDIATE—Do not wait for a timeout.
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| arraySize | ViInt32 | Pass the number of elements in the readingArray parameter. | ||
| Outputs | Type | Description | ||
| readingArray | ViReal64[] | Returns an array of the most recent measurement values. The value you specify for the function parameter of the IviDmm_ConfigureMeasurement function determines the units of this parameter. Possible Units | ||
| actualNumberof Points |
ViInt32 | Indicates the number of measured values the function places in the readingArray parameter. |
