ADLINK DAQe-2502 - Manual (Page 44)

34 Operation Theory
Using DACs’ Multiplying Characteristic
The D/A reference selection let you fully utilize the multiplying
characteristics of the DACs. Digital codes sent to the D/A convert-
ers are multiplied by the reference to generate output.
The DAQ-/DAQe-/PXI-2502/2501 card can generate standard and
arbitrary functions, continuously or piece-wisely. The Appendix
illustrates all possible waveform patterns generated by the DAQ-/
DAQe-/PXI-2502/2501 card in combination with various counters,
clock sources, and voltage references.
Software Update
This method is suitable for applications that need to generate D/A
output controlled by user programs. In this mode, the D/A con-
verter generates one output once the software command is
issued. However, it is difficult to determine the software update
rate under a multi-task OS like Windows.
Magnitude
Bipolar Unipolar
Output Output Digital Code
FSR – LSB +Vref * (2046 / 2048) Vref * (4095 / 4096) 0FFF
Midscale + LSB +Vref * (1 / 2048) Vref * (2049 4096) 0801
Midscale 0 Vref * (2048 / 4096) 0800
Midscale – LSB -Vref * ( 1 / 2048) Vref * (2047 / 4096) 07FF
-FSR + LSB -Vref * (2046 / 2048) Vref * ( 1 / 4096) 0001
-FSR -Vref 0 0000
Table 4-5: D/A Output Versus Digital Codes