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Chapter 2 Function Reference — DAQ_Monitor
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National Instruments Corporation 2-127 NI-DAQ FRM for PC Compatibles
in Lab_ISCAN_Start. If you are using an AMUX-64T, channel can be equal to any one of
the AMUX-64T channels.
Range: –1 for data from all channels being sampled.
n where n is one of the channels being sampled.
sequential is a flag that enables or disables the return of consecutive or oldest blocks of data
from the acquisition buffer. A call to
DAQ_Monitor with the value of sequential equal to one
returns a block of data that begins where the last sequential call to
DAQ_Monitor left off. A
call to
DAQ_Monitor with sequential equal to zero returns the most recent block of data
available.
0: Most recent data.
1: Consecutive data.
numPts is the number of data points you want to retrieve from the buffer being used by the
acquisition operation. If the channel parameter is equal to –1, numPts must be an integer
multiple of the number of channels contained in the scan sequence. If you are using one or
more AMUX-64T boards, remember that the actual number of channels scanned is equal to
the value of the numChans parameter you selected in
SCAN_Setup, multiplied by the
number of AMUX-64T boards, multiplied by 4.
Range: (if channel equals –1) 1 to the value of count in the
DAQ_Start, SCAN_Start,
or
Lab_ISCAN_Start call.
(if channel is not equal to 1) 1 to the number of points per channel that the
acquisition buffer can hold.
monitorBuffer is the destination buffer for the data. It is an integer array. monitorBuffer
must be at least big enough to hold numPts worth of data. Upon the return of
DAQ_Monitor,
monitorBuffer contains a snapshot of a portion of the acquisition buffer.
newestPtIndex is the offset into the acquisition buffer of the newest point returned by
DAQ_Monitor. When the value of the sequential flag is 0, newestPtIndex is useful in
determining whether you are seeing the same data over and over again. If
DAQ_buffer
is the name of the buffer selected in the
DAQ_Start call, for example,
monitorBuffer[numPts – 1] =
DAQ_buffer[newestPtIndex], if DAQ_buffer is
zero based.
daqStopped returns an indication of whether the data acquisition has completed.
0: The DAQ operation is not yet complete.
1: The DAQ operation has completed (or halted due to an error).
Note C Programmers—newestPtIndex and daqStopped are pass-by-reference
parameters.