National Instruments 321645c-01 用户手册
Chapter 2
Function Reference — WFM_DB_HalfReady
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National Instruments Corporation
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NI-DAQ FRM for PC Compatibles
WFM_DB_HalfReady
Format
status = WFM_DB_HalfReady (deviceNumber, numChans, chanVect, halfReady)
Purpose
Checks if the next half buffer for one or more channels is available for new data during a
double-buffered waveform generation operation. You can use
double-buffered waveform generation operation. You can use
WFM_DB_HalfReady
to avoid
the waiting period that can occur with the double-buffered transfer functions.
Parameters
Input
Output
Parameter Discussion
numChans indicates the number of analog output channels specified in the array chanVect.
chanVect is the user array of channel numbers indicating which analog output channels are
to be checked to see if the next half buffer for that channel is available.
Channel number range:
to be checked to see if the next half buffer for that channel is available.
Channel number range:
0 or 1 for most devices.
0 through 5 for AT-AO-6.
0 through 9 for AT-AO-10.
0 through 5 for AT-AO-6.
0 through 9 for AT-AO-10.
halfReady indicates whether the next half buffer for all of the channels specified in chanVect
is available for new data. When halfReady equals 1, you can use
is available for new data. When halfReady equals 1, you can use
WFM_DB_Transfer
to write
new data to the next half buffer(s) immediately. When halfReady equals 0, the next half
buffer for one or more channels is not ready for new data.
buffer for one or more channels is not ready for new data.
Note
C Programmers—halfReady is a pass-by-reference parameter.
Name
Type
Description
deviceNumber
i16
assigned by configuration utility
numChans
i16
number of analog output channels
chanVect
[i16]
channel numbers
Name
Type
Description
halfReady
i16
whether the next half buffer is available for new
data
data