Ai Convert Clock Timebase Signal; Ai Hold Complete Event Signal; Ai Start Trigger Signal; Using A Digital Source - National Instruments 622 Series User Manual

AI Convert Clock Timebase Signal

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.

AI Hold Complete Event Signal

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 PFI <0..15> or
RTSI <0..7> terminal.
The polarity of AI Hold Complete Event is software-selectable, but is typically configured so
that a low-to-high leading edge can clock external AI multiplexers indicating when the input
signal has been sampled and can be removed.

AI Start Trigger Signal

Use the AI Start Trigger (ai/StartTrigger) signal to begin a measurement acquisition. A
measurement acquisition consists of one or more samples. If you do not use triggers, begin a
measurement with a software command. Once the acquisition begins, configure the acquisition
to stop:
• When a certain number of points are sampled (in finite mode)
• After a hardware reference trigger (in finite mode)
• With a software command (in continuous mode)
An acquisition that uses a start trigger (but not a reference trigger) is sometimes referred to as a
posttriggered acquisition.

Using a Digital Source

To use AI Start Trigger with a digital source, specify a source and an edge. The source can be
any of the following signals:
• PFI <0..15>
• RTSI <0..7>
Counter n Internal Output
•
• PXI_STAR
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