Chapter 2 Function Reference — WFM_DB_Half Ready
NI-DAQ FRM for PC Compatibles 2-414
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National Instruments Corporation
Using This Function
Double-buffered waveform generation functions cyclically output data from the waveform
buffer (specified in WFM_Load). The waveform buffer is divided into two equal halves so that
NI-DAQ can write data from one half of the buffer to the output channels while filling the
other half of the buffer with new data. This mechanism makesit necessary to write to both
halves of the waveform buffer alternately so that NI-DAQ does not output the old data. Use
WFM_DB_Transfer to transfer new data to a waveform buffer half. Both of these functions,
when called, wait until NI-DAQ cancomplete the data transfer before returning. During
slower paced waveform generationoperations, this waiting period can be significant. You
canuse WFM_DB_HalfReady to call the transfer functions only when NI-DAQ can make the
transfer immediately.
Refer to the Double-Buffered Waveform Generation Applications section, in Chapter 5 of the
NI-DAQ User Manual for PC Compatibles, for an explanation of double buffering.