Chapter 5
Analog Output
X Series User Manual
5-2
ni.com
•
AO Sample Clock
—The AO Sample Clock signal reads a sample
from the DAC FIFO and generates the AO voltage.
•
AO Reference Selection
—The AO reference selection signal allows
yo
u
to change the range of the analog o
u
tp
u
ts.
AO Reference Selection
AO reference selection allows yo
u
to set the analog o
u
tp
u
t range. The
analog o
u
tp
u
t range describes the set of voltages the device can generate.
The digital codes of the DAC are spread evenly across the analog o
u
tp
u
t
range. So, if the range is smaller, the analog o
u
tp
u
t has better resol
u
tion;
that is, the voltage o
u
tp
u
t difference between two consec
u
tive codes is
smaller. Therefore, the analog o
u
tp
u
t is more acc
u
rate.
The analog o
u
tp
u
t range of a device is all of the voltages between:
–AO Reference and +AO Reference
The possible settings for AO reference depend on the device model. For
models not described below, refer to the specifications for yo
u
r device.
•
(NI 6321/6323/634
x
Devices)
On NI 6321/6323/634
x
devices, the AO
reference is always 10 V. So, for NI 6321/6323/634
x
devices, the
analog o
u
tp
u
t range eq
u
als ±10 V.
•
(NI 635
x
/636
x
Devices)
On NI 635
x
/636
x
devices, the AO reference of
each analog o
u
tp
u
t (AO <0..3>) can be individ
u
ally set to one of the
following:
–
10 V
–
5 V
–
APFI <0,1>
Yo
u
can connect an external signal to APFI <0,1> to provide the AO
reference. The AO reference can be a positive or negative voltage. If
AO reference is a negative voltage, the polarity of the AO o
u
tp
u
t is
inverted. The valid ranges of APFI <0,1> are listed in the device
specifications.
Yo
u
can
u
se one of the AO <0..3> signals to be the AO reference for a
different AO signal. However, yo
u
m
u
st externally connect this
channel to APFI 0 or APFI 1.
Note
When
u
sing an external reference, the o
u
tp
u
t signal is not calibrated in software. Yo
u
can generate a val
u
e and meas
u
re the voltage offset to calibrate yo
u
r o
u
tp
u
t in software.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com