ADLINK DAQe-2006 - Manual (Page 41)

Operation Theory 29
4 Operation Theory
The operation theory of the DAQ-/DAQe-/PXI-2016/2010/2006/
2005 card functions are described in this chapter. The functions
include the A/D conversion, D/A conversion, digital I/O, and gen-
eral purpose counter/timer. The operation theory can help you
understand how to configure and program the DAQ-/DAQe-/PXI-
2016/2010/2006/2005 card.
The whole DAQ/DAQe/PXI card series, including the DAQ-/DAQe-
/PXI-2010/2000 Series, DAQ/DAQe/PXI-2200 Series, and DAQ/
DAQe/PXI-2500 Series, are designed based on the same logic-
timing template of DAQ/DAQe/PXI-22XX. In the DAQ/PXI-22XX
cards, all the A/D related timings are for multiplexing A/D sampling
based on scanning, so that DAQ-/DAQe-/PXI-2016/2010/2006/
2005 card also adopts the same concept, except there is only one
conversion signal in a scan which could generate up to four sam-
ples from the four different channels at the same time. In the fol-
lowing description, to conform to the original timing design, we still
use scan as the unit of A/D data acquisition. All the DA and GPTC
functions are the same in DAQ-/DAQe-/PXI-2016/2010/2006/2005
card and DAQ/DAQe/PXI-2200 Series, while DAQ/DAQe/PXI-
2500 Series provides improved DA timing compared to the two
earlier series.
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.