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Digitize command not returning entire waveform.

Question asked by gradi3nt on Aug 16, 2013
Hello,

I'm using GPIB and labview to control an Agilent DSO5014A. I am trying to obtain data from a single sweep of the scope and manipulate it in Labview. When I input a single sine wave pulse (from an arb function generator) into channel 1 of the scope and then use the digitize command, I get the full wave as expected. When I send an inverted pulse (-1*sin(w*t)) and use the exact same scope configuration and then obtain the data with digitize, I see the full inverted sin wave the the display of the scope, but Labview only receives half of the points from the pulse. Why isn't digitize giving me all of the waveform from the screen? 

I stress that all I am changing in my Labview file to cause this behavior is typing '-1' in front of the code that makes the waveform. Everything else is unchanged. 

I have made many attempts at isolating the problem but I can't figure this out, and the documentation on digitize hasn't helped me figure this one out. I really appreciate any advice you guys have!

Configuration commands:
*RST
:TRIG:EDGE:SOUR EXT
:TRIG:EDGE:SLOP NEG
:TRIG:EDGE:LEV 0.3,EXT
:TRIG:SWE NORM
:CHAN1:RANG 40
:CHAN2:RANG 24
:TIM:RANG       // These constants don't change when I invert the wave.
:TIM:DEL
:DIG CHAN1,CHAN2                     // There is another signal going into channel 2, but all of that waveform is always acquired without a problem 
// Trigger function generator, waveform appears on the scope's display
:WAV:FORM ASCII
:WAV:SOUR CHAN1
:WAV:POIN 1000
:WAV:DATA?
// Receive and inspect data from ch 1
:WAV:SOUR CHAN2
:WAV:DATA?
// Receive and inspect data from ch 2

I have tried to include all relevant info, but if there's more you need to know I will provide it.

Thanks!!
Julian I.

Edited by: gradi3nt on Aug 16, 2013 10:02 AM (fixed formatting, preview button not working)

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