Read Waveform VI bottleneck in LabVIEW

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jdetlefs
Posts: 7
Joined: Wed Dec 22, 2021 10:01 pm

Read Waveform VI bottleneck in LabVIEW

Post by jdetlefs » Wed Jan 26, 2022 11:50 pm

Hey All,

I have come across a bottleneck that is reading buffers in LabVIEW and am looking for help/guidance.

Using the provided example, "Signal Acquisition on external trigger", I framed
the multiple subVIs on the back panel in sequence frames and timed each one using the high resolution clock.

I am reading a 100KHz sinewave 1Vpp input onto channel one for the test.
CH1 positive edge trigger
zero (0.00) mV trigger level
delay of 8192 samples

Here are my results:

configure acquisition: ~ 69 microSec
configure edge trigger: ~45 microSec
triggered acquisition: ~24 microSec
wait for trigger: ~ 93 milliSec
read waveform: ~261.7 milliSec or .2617 Sec
plotting: ~ 28 microSec

The read waveform vi doubles to .5237 Sec if I read both channels 1 and 2.

The sample rate or decimation have no effect on the time it takes for the "Read Waveform VI" to execute. This seems to be where the bottleneck occurs.

My thoughts are that the data is written to the buffer at the full 125MHz to both channels but reading the buffers is slow. The fact it doubles in time when reading both channels is in line with that it can only read one buffer at a time.

Is there a way to read the buffers faster?

Regards,
Jdetlefs

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