National Instruments X Series User Manual page 72

X Series User Manual
the device recognizes an AI Sample Clock pulse, it causes an error if it receives an AI Sample
Clock pulse before the correct number of AI Convert Clock pulses are received.
Figures 4-18, 4-19, 4-20, and 4-21 show timing sequences for a four-channel acquisition (using
AI channels 0, 1, 2, and 3) and demonstrate proper and improper sequencing of AI Sample Clock
and AI Convert Clock.
Figure 4-18. Scan Overrun Condition; AI Sample Clock Too Fast For Convert Clock
Causes an Error
AI Sample Clock
AI Convert Clock
Channel Measured 0 1 2 3
Convert Period
Figure 4-19. AI Convert Clock Too Fast For AI Sample Clock;
AI Convert Clock Pulses Are Ignored
AI Sample Clock
AI Convert Clock
0 1 2 3 0 1 2 3 0 1 2 3
Channel Measured
Sample #1 Sample #2 Sample #3
Figure 4-20. AI Sample Clock and AI Convert Clock Improperly Matched;
Leads to Aperiodic Sampling
AI Sample Clock
AI Convert Clock
0 1 2 3
0 1 2 3 0
Channel Measured
Sample #1 Sample #2 Sample #3
Figure 4-21. AI Sample Clock and AI Convert Clock Properly Matched
AI Sample Clock
AI Convert Clock
Channel Measured 0 1 2 3 0 1 2 3 0 1 2 3
Sample #1 Sample #2 Sample #3
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