National Instruments AT E Series - Manual (Page 156)

Appendix C Common Questions
AT E Series User Manual C-4 ni.com
I’m using the DACs to generate a waveform, but I discovered with a
digital oscilloscope that there are glitches on the output signal. Is this
normal?
When it switches from one voltage to another, any DAC produces glitches
due to released charges. The largest glitches occur when the most
significant bit (MSB) of the D/A code switches. You can build a lowpass
deglitching filter to remove some of these glitches, depending on the
frequency and nature of the output signal. The AT-MIO-16E-1,
AT-MIO-16E-2 and the AT-MIO-64E-3 devices have built-in reglitchers,
which can be enabled through software, on their AO channels. Refer to
the
Analog Output Reglitch Selection section of Chapter 3, Hardware
Overview , for more information about reglitching.
Can I synchronize a one-channel AI data acquisition with a
one-channel AO waveform generation on my AT E Series device?
Yes. One way to accomplish this synchronization is to use the waveform
generation timing pulses to control the AI data acquisition. To do this,
follow steps 1 through 4, in addition to the usual steps for data acquisition
and waveform generation configuration.
1. Enable the PFI5 line for output, as follows:
If you are using NI-DAQ, call Select_Signal(deviceNumber,
ND_PFI_5, ND_OUT_UPDATE, ND_HIGH_TO_LOW) .
If you are using LabVIEW, invoke Route Signal VI with signal name
set to PFI5 and signal source set to AO Update.
2. Set up DAQ timing so that the timing signal for A/D conversion comes
from PFI5, as follows:
If you are using NI-DAQ, call Select_Signal(deviceNumber,
ND_IN_CONVERT, ND_PFI_5, ND_HIGH_TO_LOW) .
If you are using LabVIEW, invoke AI Clock Config VI with clock
source code set to PFI pin, high to low, and clock source string set to 5.
3. Initiate AI data acquisition, which starts only when the AO waveform
generation starts.
For example, if you are using NI-DAQ, you can call DAQ_Start with
appropriate parameters.
Similarly, if you are using LabVIEW, you can invoke AI Control VI
with control code set to 0 (start).