Analog Output Triggering Signals; Analog Output Timing Signals; Ao Sample Clock Signal - National Instruments cRIO-904 Series User Manual

the host buffer at any time without disrupting the output. There is no limitation on
the number of waveform channels supported by regeneration mode.
– With onboard regeneration, the entire buffer is downloaded to the FIFO and
regenerated from there. After the data is downloaded, new data cannot be written to
the FIFO. To use onboard regeneration, the entire buffer must fit within the FIFO
size. The advantage of using onboard regeneration is that it does not require
communication with the main host memory once the operation is started, which
prevents problems that may occur due to excessive bus traffic or operating system
latency. There is a limit of 16 waveform channels for onboard regeneration.
– With non-regeneration, old data is not repeated. New data must continually be
written to the buffer. If the program does not write new data to the buffer at a fast
enough rate to keep up with the generation, the buffer underflows and causes an
error. There is no limitation on the number of waveform channels supported by non-
regeneration.

Analog Output Triggering Signals

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.
Analog output supports two different triggering actions: AO Start Trigger and AO Pause
Trigger. An analog or digital signal can initiate these 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. An analog trigger can be supplied by some C Series analog modules.
Refer to the AO Start Trigger Signal
information about the analog output trigger signals.

Analog Output Timing Signals

The cRIO controller features the following AO (waveform generation) timing signals:
• AO Sample Clock
• AO Sample Clock Timebase Signal
• AO Start Trigger
• AO Pause Trigger
Signals with an * support digital filtering. Refer to the
information.

AO Sample Clock Signal

The AO sample clock signals when all the analog output channels in the task update. AO
Sample Clock can be generated from external or internal sources as shown in the figure below.
56 | ni.com | cRIO-904x User Manual
and AO Pause Trigger Signal
Signal*
Signal*
Signal*
sections for more
PFI Filters section for more