User manual

Chapter 4 NI-DAQ Double Buffering

NI-DAQ User Manual for PC Compatibles 4-6 ni.com

Double-Buffered Output Operations

Double-buffered output operations are similar to input operations. The

circular buffer is again logically divided into two halves. By dividing the

buffer into two halves, NI-DAQ can coordinate user access to the data

buffer with the DAQ device. The coordination scheme is simple—NI-DAQ

copies data from a transfer buffer you create to the circular buffer in

sequential halves. The data in the transfer buffer can be updated

between transfers.

Figure 4-4 illustrates a series of sequential data transfers.

Figure 4-4. Double-Buffered Output with Sequential Data Transfers

Outgoing

Device Data

Circular Buffer

Transfer Buffer

Empty Buffer

Data Ready

for Output

Successfully

Output Data

c. d.