© National Instruments
|
4-29
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
