Adlink DAQe-2006 Manual do Utilizador descarregar pdf (Página 59)

Operation Theory 47

4.2 D/A Conversion

There are two 12-bit D/A output channels available in the DAQ-/

DAQe-/PXI-2016/2010/2006/2005 card. When using D/A convert-

ers, you should assign and control the D/A converter reference

sources for the D/A operation mode and D/A channels. You could

also set the output polarity to unipolar or bipolar.

The reference selection control lets you utilize in full the multiply-

ing characteristics of the D/A converters. Internal 10V reference

and external reference inputs are available in the DAQ-/DAQe-/

PXI-2016/2010/2006/2005 card. The range of the D/A output is

directly related to the reference. The digital codes that are updated

to the D/A converters will multiply with the reference to generate

the analog output. While using internal 10V reference, the full

range would be –10V to +9.9951V in the bipolar output mode, and

0V to 9.9976V in the unipolar output mode. While using an exter-

nal reference, you can reach different output ranges by connecting

different references. For example, if connecting a DC –5V with the

external reference, then you can get a full range from –4.9976V to

+5V in the bipolar output with inverting characteristics due to the

negative reference voltage. You could also have an amplitude

modulated (AM) output by feeding a sinusoidal signal into the ref-

erence input. The range of the external reference should be within

±10V. Table 4-5 and 4-6 illustrates the relationship between digital

code and output voltages

with Vref=10V and if internal reference is

selected

Digital Code Analog Output

111111111111 Vref * (2047/2048)

100000000001 Vref * (1/2048)

100000000000 0V

011111111111 -Vref * (1/2048)

000000000000 -Vref

Table 4-5: Bipolar Output Code Table

1 2 ... 54 55 56 57 58 59 60 61 62 63 64 ... 91 92

Sem comentários

Adlink DAQe-2006 Manual do Utilizador Página 59