User's Manual

Chapter 7 Analog Output
NI USB-621x User Manual 7-6 ni.com
The source also can be one of several internal signals on your DAQ device.
Refer to Device Routing in MAX in the NI-DAQmx Help or the
LabVIEW 8.x Help for more information.
You also can specify whether the waveform generation begins on the rising
edge or falling edge of ao/StartTrigger.
Routing AO Start Trigger Signal to an Output
Terminal
You can route ao/StartTrigger out to any PFI <4..7> or PFI <12..15>
terminal.
The output is an active high pulse.
AO Pause Trigger Signal
Use the AO Pause Trigger signal (ao/PauseTrigger) to mask off samples in
a DAQ sequence. That is, when ao/PauseTrigger is active, no samples
occur.
ao/PauseTrigger does not stop a sample that is in progress. The pause does
not take effect until the beginning of the next sample.
If you are using any signal other than the onboard clock as the source of
your sample clock, the generation resumes as soon as the pause trigger is
deasserted and another edge of the sample clock is received, as shown in
Figure 7-4.
Figure 7-4. ao/PauseTrigger with Other Signal Source
Using a Digital Source
To use ao/PauseTrigger, specify a source and a polarity. The source can be
the PFI <0..3> or PFI <8..11> signals.
Pause Trigger
Sample Clock