Controlling a Particle Image Velocimetry (PIV) System with DAQmx

Updated May 3, 2018

Reported In

Driver

  • NI-DAQmx

Issue Details

  • I am currently making a Particle Image Velocimetry (PIV) system. I am using DAQ hardware and NI-DAQmx. My program needs to output several specific pulses after it receives an external trigger.
  • I want to control my PIV system using LabVIEW and DAQmx. I need my application to fire a pulsed laser several times per second while my external trigger signal is high.
  • We have a PIV system with two lasers. I need to read a signal line and see if there is a trigger. When the trigger happens I want to fire both lasers alternately, each one ten times with 10 Hz. The two lasers shall fire 10 µs apart every time.

Solution

Syncing (dual) lasers and Q-switches to an external trigger as it is often needed in Particle Image Velocimetry (PIV) systems can be easily done with Retriggerable Tasks in NI-DAQmx: Each time your DAQ hardware receives the external trigger it will fire the pulses you defined.

It is both possible to:

  • Output a pulse/finite train of pulses every time an external trigger is obtained.
  • Send such an output continuously as long as the eternal trigger signal is active through using a Pause Trigger. Pause Triggers are described in section F and G of this article: NI-DAQmx Data Acquisition Triggering Techniques Using LabVIEW.

Additional Information

As this task is using the DAQ's hardware timed input/output resources, there is no software jitter introduced.

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