A buffer is a temporary storage in computer memory for acquired or to-be-generated samples. Typically this storage is allocated from your computer's memory and is also called the task buffer. For input operations, a data transfer mechanism transfers samples from your device into the buffer where they wait for a call to the Read function/VI to copy the samples to your application. For output operations, the Write function/VI copies samples into the buffer where they wait for the data transfer mechanism to transfer them to your device.
When Is a Buffer Created?
If you use the Timing function/VI and set the sample mode to finite or continuous, NI-DAQmx creates a buffer. If you set sample mode to Hardware Timed Single Point, NI-DAQmx does not create a buffer.
If you set the Data Transfer Mechanism to Programmed I/O or set the buffer size to zero by using either the Input or Output Buffer Config function/VIs, NI-DAQmx does not create a buffer (even if you also used the Timing function/VI). A data transfer mechanism of programmed I/O means there is no buffer.