ADLINK DAQe-2502 - Manual (Page 31)

Operation Theory 21
4 Operation Theory
The operation theories of the DAQ-/DAQe-/PXI-2502/2501 card
are described in this chapter. The functions include A/D conver-
sion, D/A conversion, digital I/O, and general purpose counter/
timer. This operation theory will help you understand how to con-
figure and program the DAQ-/DAQe-/PXI-2502/2501 card.
4.1 A/D Conversion
When using an A/D converter, you must know about the properties
of the signal to be measured. You may decide which channel to
use and how to connect the signals to the card. Refer to section
3.4. In addition, users should define and control the A/D signal
configurations, including channels, gains, and polarities (unipolar/
bipolar).
The A/D acquisition is initiated by a trigger source and you must
decide how to trigger the A/D conversion. The data acquisition will
start once a trigger condition is matched.
After the end of an A/D conversion, the A/D data is buffered in a
Data FIFO. The A/D data can now be transferred into the system
memory for further processing.
Software polling and programmable scan acquisition modes are
described in this chapter, as well as timing, trigger modes, trigger
sources, and transfer methods.