Chapter 4

Analog Input

Using a Digital Source

To use ai/ReferenceTrigger with a digital source, specify a source and an edge. The source can be the PFI <0..3> or PFI <8..11> signals.

The source also can be one of several internal signals on your DAQ device. Refer to Device Routing in MAX in the NI-DAQmx Help or the LabVIEW 8.x Help for more information.

You also can specify whether the measurement acquisition stops on the rising edge or falling edge of ai/ReferenceTrigger.

Routing AI Reference Trigger Signal to an Output

Terminal

You can route ai/ReferenceTrigger out to any PFI <4..7> or PFI <12..15> terminal.

AI Pause Trigger Signal

You can use the AI Pause Trigger (ai/PauseTrigger) signal to pause and resume a measurement acquisition. The internal sample clock pauses while the external trigger signal is active and resumes when the signal is inactive. You can program the active level of the pause trigger to be high or low.

Using a Digital Source

To use ai/SampleClock, specify a source and a polarity. The source can be the PFI <0..3> or PFI <8..11> signals.

The source also can be one of several other internal signals on your DAQ device. Refer to Device Routing in MAX in the NI-DAQmx Help or the LabVIEW 8.x Help for more information.

© National Instruments Corporation

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NI USB-621x User Manual