National Instruments NI 6323 User Manual

Chapter 4 Analog Input
© National Instruments 4-31 X Series User Manual
AI Convert Clock Signal
Use the AI Convert Clock (ai/ConvertClock) signal to initiate a single A/D
conversion on a single channel. A sample (controlled by the AI Sample
Clock) consists of one or more conversions.
You can specify either an internal or external signal as the source of
AI Convert Clock. You also can specify whether the measurement sample
begins on the rising edge or falling edge of AI Convert Clock.
With NI-DAQmx, the driver chooses the fastest conversion rate possible
based on the speed of the A/D converter and adds 10 μs of padding between
each channel to allow for adequate settling time. This scheme enables the
channels to approximate simultaneous sampling and still allow for
adequate settling time. If the AI Sample Clock rate is too fast to allow for
this 10 μs of padding, NI-DAQmx chooses the conversion rate so that the
AI Convert Clock pulses are evenly spaced throughout the sample.
To explicitly specify the conversion rate, use AI Convert Clock Rate
DAQmx Timing property node or function.
Caution Setting the conversion rate higher than the maximum rate specified for your
device will result in errors.
Using an Internal Source
One of the following internal signals can drive AI Convert Clock:
• AI Convert Clock Timebase (divided down)
•Counter n Internal Output
• Change Detection Event
•Counter n Sample Clock
• AO Sample Clock (ao/SampleClock)
• DI Sample Clock (di/SampleClock)
• DO Sample Clock (do/SampleClock)
A programmable internal counter divides down the AI Convert Clock
Timebase to generate AI Convert Clock. The counter is started by AI Sample
Clock and continues to count down to zero, produces an AI Convert Clock,
reloads itself, and repeats the process until the sample is finished. It then
reloads itself in preparation for the next AI Sample Clock pulse.
Several other internal signals can be routed to AI Convert Clock through
internal routes. Refer to Device Routing in MAX in the NI-DAQmx Help or
the LabVIEW Help for more information.
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National Instruments NI 6323 Specifications

General

Brand	National Instruments
Model	NI 6323
Category	I/O Systems
Language	English