Ni pxi 5122 stays idle after acq arm (start) trigger

[JoeSchmoe]

I am trying to do continuous acquisition on a 5122 but also only start after a trigger.  The only way i've figured this to work is if i leave the scope idle and have it go active on trigger (which is what the acq arm is supposed to do).

Configuring the fetch_relative_to attr to trigger allows me to wait for a trigger, but prevents continuous acquisition because the fetch call will always call from the same spot.  For this reason i need to set the attr to read pointer, but then fetch will return pretrigger samples, so i want to stay idle until trigger.

The problem is that the scope is staying idle even after configuring acq arm and triggering on that configuration, am I understanding its functionality incorrectly?

[nestorl]

Hi @JoeSchmoe,

Have you checked out this help resource on Acquiring Data Continuously with our scopes?

[JoeSchmoe · Accepted solution]

Yes,

I have solved my problem, actually.  I tried to use the acq arm start trigger as a replacement for initiate acquisition (assuming the purpose of initiate was to go from idle to active pre-trigger).  As it turns out, the proper way is instead to configure your acq arm source, then call initiate acquisition, your scope will remain idle until the trigger is sent.