National Instruments NI USB-621x - Manual (Page 38)

Chapter 4 Analog Input
NI USB-621x User Manual 4-12 ni.com
Figure 4-4. Analog Input Timing Options
M Series devices use ai/SampleClock and ai/ConvertClock to perform
interval sampling. As Figure 4-5 shows, ai/SampleClock controls the
sample period, which is determined by the following equation:
1/Sample Period = Sample Rate
Figure 4-5. Interval Sampling
ai/ConvertClock controls the Convert Period, which is determined by the
following equation:
1/Convert Period = Convert Rate
20 MHz Timebase
100 kHz Timebase
Programmable
Clock
Divider
Programmable
Clock
Divider
ai/SampleClock
Timebase
ai/ConvertClock
Timebase
Analog Comparison Event
Ctr n Internal Output
SW Pulse
Ctr n Internal Output
ai/ConvertClock
ai/SampleClock
Channel 0
Channel 1
Convert Period
Sample Period