National Instruments USB-621 Series, User Manual

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Chapter 5 Analog Output
© National Instruments Corporation 5-5 NI USB-621x User Manual
Analog Output Timing Signals
Fig u re 5-3 s u mmarizes all of the timing options provided by the analog
o u tp u t timing engine.
Figure 5-3. Analog Output Timing Options
USB-621 x devices feat u re the following AO (waveform generation) timing
signals:
• AO Start Trigger Signal
• AO Pause Trigger Signal
• AO Sample Clock Signal
• AO Sample Clock Timebase Signal
AO Start Trigger Signal
Use the AO Start Trigger (ao/StartTrigger) signal to initiate a waveform
generation. If yo
u do not u se triggers, yo u can begin a generation with a
software command.
Using a Digital Source
To u se AO Start Trigger, specify a so u rce and an edge. The so u rce can be
one of the following signals:
• A p u lse initiated by host software
• (USB-6211/6215 Devices) PFI <0..3>
•
(USB-6212/6216 Devices)
PFI <0..15>
20 MHz Time bas e
100 kHz Time bas e
Progr a mm ab le
Clock
Divider
AO Sa mple Clock
Time bas e
Ctr n Intern a l O u tp u t
AO Sa mple Clock
PFI
PFI
Sa mple Clock
Time bas e Divi s or