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Chapter 2 Function Reference — DAQ_Monitor
NI-DAQ FRM for PC Compatibles 2-128
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National Instruments Corporation
Using This Function
DAQ_Monitor is intended to return small blocks of data from a background acquisition
operation. This is especially useful when you have put the acquisition in a circular mode
by enabling either the double-buffered or pretrigger modes. The operation is not disturbed;
NI-DAQ only reads data from the buffer being used by the acquisition. If the amount of data
requested is not yet available,
DAQ_Monitor returns the appropriate error code. Possible uses
for
DAQ_Monitor include deciding when to halt an acquisition based on a level, slope, or
peak. If you are using
DAQ_Monitor to retrieve sequential data (during a circular acquisition)
and NI-DAQ overwrites a block of data before it can copy the data, NI-DAQ returns an
overWriteError warning.
DAQ_Monitor then restarts sequential retrieval with the most
recently acquired block of data.
If NI-DAQ overwrites a block of data as it is copied to monitorBuffer, NI-DAQ returns the
overWriteError error. The data in monitorBuffer might be corrupted if NI-DAQ returns this
error.