National Instruments DAQ PCI E Series User Manual - page 52

Chapter 2

Analog Input

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 National Instruments Corporation

2-19

E Series User Manual

The output is an active high pulse. Figure 2-8 shows the timing behavior of 

the PFI 1/AI REF TRIG pin configured as an output.

Figure 2-8.  

PFI 1/AI REF TRIG Timing Behavior

The PFI 1/AI REF TRIG pin is configured as an input by default.

AI Pause Trigger Signal

You can use the AI Pause Trigger (ai/PauseTrigger) signal to pause and 

resume a measurement acquisition. This signal is not available as an output.

Using a Digital Source

To use ai/PauseTrigger, specify a source and a polarity. The source can be 

an external signal connected to any PFI or RTSI  pin. The source can 

also 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.

Also, specify whether the measurement sample is paused when 

ai/PauseTrigger is at a logic high or low level.

Using an Analog Source

When you use an analog trigger source, the internal sample clock pauses 

when the Analog Comparison Event signal is low and resumes when the 

signal goes high (or vice versa). Refer to the 

Triggering with an Analog 

Source

 section of Chapter 10, 

Triggering

, for more information on analog 

trigger sources.

Note

Pause triggers are only sensitive to the level of the source, not the edge.

t

w

t

w

 = 50 to 100 ns