information and wiring diagrams, refer to the documentation included with your C Series
modules.
The cRIO controller has eight input timing engines, which means that up to eight hardware-
timed analog input tasks can be running at a time on the controller. An analog input task can
include channels from multiple analog input modules. However, channels from a single
module cannot be used in multiple tasks.
Multiple timing engines allow the cRIO controller to run up to eight analog input tasks
simultaneously, each using independent timing and triggering configurations. The eight timing
engines are it0, it1,…it7.
Analog Input Triggering Signal
A trigger is a signal that causes an action, such as starting or stopping the acquisition of data.
When you configure a trigger, you must decide how you want to produce the trigger and the
action you want the trigger to cause. The cRIO controller supports internal software triggering,
external digital triggering, analog triggering, and internal time triggering.
Three triggers are available: Start Trigger, Reference Trigger, and Pause Trigger. An analog or
digital signal can initiate these three trigger actions. C Series Parallel digital input modules and
the controller’s integrated PFI trigger line can be used in any controller slot to supply a digital
trigger. To find your module triggering options, refer to the documentation included with your
C Series modules. For more information about using digital modules for triggering, refer to the
Digital Input/Output with NI-DAQmx section.
Refer to the AI Start Trigger Signal, AI Reference Trigger Signal, and AI Pause Trigger Signal
sections for more information about the analog input trigger signals.
Hardware-Timed Single Point (HWTSP) Mode
In HWTSP mode, samples are acquired or generated continuously using hardware timing and
no buffer. You must use the sample clock or change detection timing types. No other timing
types are supported.
Use HWTSP mode if you need to know if a loop executes in a given amount of time, such as
in a control application. Because there is no buffer, if you use HWTSP mode, ensure that reads
or writes execute fast enough to keep up with hardware timing. If a read or write executes late,
it returns a warning.
Note DSA modules do not support HWTSP mode.
Analog Input Timing Signals
The cRIO controller features the following analog input timing signals:
• AI Sample Clock Signal*
• AI Sample Clock Timebase Signal
• AI Start Trigger Signal*
48 | ni.com | cRIO-904x User Manual
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