Ai Convert Clock Timebase Signal; Ai Hold Complete Event Signal - National Instruments Data Acquisition Device NI USB-621x User Manual

AI Convert Clock Timebase Signal

AI Hold Complete Event Signal

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AI Sample Clock
AI Convert Clock
Channel Measured
Figure 4-13. AI Sample Clock and AI Convert Clock Properly Matched
A single external signal can 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 4-14 shows this timing relationship.
AI Sample Clock
AI Convert Clock
Channel Measured
Figure 4-14. Single External Signal Driving AI Sample Clock and
The AI Convert Clock Timebase (ai/ConvertClockTimebase) signal is
divided down to provide one of the possible sources for AI Convert Clock.
Use one of the following signals as the source of AI Convert Clock
Timebase:
• AI Sample Clock Timebase
• 20 MHz Timebase
AI Convert Clock Timebase is not available as an output on the
I/O connector.
The AI Hold Complete Event (ai/HoldCompleteEvent) signal generates a
pulse after each A/D conversion begins. You can route AI Hold Complete
Event out to any output PFI terminal.
0 1 2 3 0
Sample #1 Sample #2
0 1 2 3
Sample #1 Sample #2 Sample #3
AI Convert Clock Simultaneously
4-19
Chapter 4 Analog Input
1 2 3 0 1 2 3
Sample #3
0 1 2 3 0 1 ...
NI USB-621x User Manual