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Chapter 2 Function Reference — Lab_ISCAN_Check
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National Instruments Corporation 2-265 NI-DAQ FRM for PC Compatibles
sample from channel 1, the oldest data point belongs to channel 0. So finalScanOrder
returns:
finalScanOrder[0] = 0.
finalScanOrder[1] = 2.
finalScanOrder[2] = 1.
So the first sample in the buffer belongs to channel 0, the second sample belongs to channel
2, the third sample belongs to channel 1, the fourth sample belongs to channel 0, and so on.
Note C Programmers—daqStopped and retrieved are pass-by-reference parameters.
Using This Function
Lab_ISCAN_Check checks the current background data acquisition operation to determine
whether it has completed and returns the number of samples acquired at the time that you
called
Lab_ISCAN_Check. If the operation is complete, Lab_ISCAN_Check sets
daqStopped = 1. Otherwise, daqStopped is set to 0. Before
Lab_ISCAN_Check returns
daqStopped = 1, it calls
DAQ_Clear, allowing another Start call to execute immediately.
If
Lab_ISCAN_Check returns an overFlowError or an overRunError, NI-DAQ has
terminated the data acquisition operation because of lost A/D conversions due to a sample rate
that is too high (sample interval was too small). An overFlowError indicates that the A/D
FIFO memory overflowed because the data acquisition servicing operation was not able to
keep up with sample rate. An overRunError indicates that the data acquisition circuitry
was not able to keep up with the sample rate. Before returning either of these error codes,
Lab_ISCAN_Check calls DAQ_Clear to terminate the operation and reinitialize the data
acquisition circuitry.