National Instruments PCI-6281, User Manual

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Chapter 4 Analog Input
Figure 4-19. AI Convert Clock Too Fast For AI Sample Clock; AI Convert Clock Pulses Are
Gated Off
Figure 4-20.
AI Sample Clock and AI Convert Clock Improperly Matched;
Leads to Aperiodic Sampling
Figure 4-21. AI Sample Clock and AI Convert Clock Properly Matched
It is also possible to use a single external signal to drive both AI Sample Clock and AI Convert
Clock at the same time. In this mode, each tick of the external clock causes a conversion on the
ADC. Figure 4-22 shows this timing relationship.
Figure 4-22. One External Signal Driving Both Clocks Simultaneously
AI Sa mple Clock
AI Convert Clock
Sa mple #1 Sa mple #2 Sa mple # 3
1 2 3 0 1 2 3 0 1 2 3 0 Ch a nnel Me asu red
AI Sa mple Clock
AI Convert Clock
Sa mple #1 Sa mple #2 Sa mple # 3
1 2 3 0 0
Ch a nnel Me asu red
1 2 3 0
AI Sa mple Clock
AI Convert Clock
Sa mple #1 Sa mple #2 Sa mple # 3
Ch a nnel Me asu red 1 2 3 0 1 2 3 0 1 2 3 0
AI Sa mple Clock
AI Convert Clock
Sa mple #1 Sa mple #2 Sa mple # 3
1 2 3 0
1 2 3 0 1 … 0
Ch a nnel Me asu red