Справочник Пользователя для National Instruments 321645c-01

Chapter 2

Function Reference — DAQ_Check

©

 National Instruments Corporation

2-115

NI-DAQ FRM for PC Compatibles

Checks whether the current DAQ operation is complete and returns the status and the number 
of samples acquired to that point.

 

daqStopped returns an indication of whether the data acquisition has completed.

0:

The DAQ operation is not yet complete.

1:

The DAQ operation has stopped. Either the buffer is full, or an error has occurred.

retrieved indicates the progress of an acquisition. The meaning of retrieved depends 
on whether pretrigger mode has been enabled (see 

DAQ_StopTrigger_Config

). If 

pretrigger mode is disabled, retrieved returns the number of samples collected by the 
acquisition at the time of the call to 

DAQ_Check

. The value of retrieved increases until 

it equals the count indicated in the call that initiated the acquisition, at which time the 
acquisition terminates. However, if pretrigger mode is enabled, retrieved returns the offset of 
the position in your buffer where the next data point is placed when it is acquired. When the 
value of retrieved reaches count-1 and rolls over to 0, the acquisition begins to overwrite old 
data with new data. When NI-DAQ applies a signal to the stop trigger input, the acquisition 
collects an additional number of samples indicated by ptsAfterStoptrig in the call to 

DAQ_StopTrigger_Config

 and then terminates. When 

DAQ_Check

 returns a status of 1, 

retrieved contains the offset of the oldest data point in the array (assuming that the 
acquisition has written to the entire buffer at least once). In pretrigger mode, 

DAQ_Check

 

i16

assigned by configuration utility

i16

indication of whether the data acquisition has 
completed

u32

progress of an acquisition