User manual

Appendix C Common Questions

I am 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 your output signal.

Can I synchronize a one-channel analog input data acquisition with a

one-channel analog output waveform generation on my

PCI-6034E/6035E/6036E device?

Yes. One way to accomplish synchronization is to use the waveform

generation timing pulses to control the analog input data acquisition. To do

this, follow steps 1 through 4 below, 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, call the Route Signal VI with signal

name set to PFI5 and signal source set to AO Update.

2. Set up data acquisition 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)

• IfyouareusingLabVIEW,calltheAIClockConfigVIwithclock

source code set to PFI pin, high to low, and clock source string set

to 5.

3. Initiate analog input data acquisition, which starts only when the

analog output waveform generation starts.

4. Initiate analog output waveform generation.

UM.book Page 3 Monday, May 14, 2001 10:32 AM