MSO Analog Trigger does not work

[WilliamEarle]

I assume based on the value I set for limit virtual bench selects the next higer range (like DAQmx).

Yep. You can read back what it got coerced to with MSO Query Analog Channel.

I am trying to implement the averaging in LabVIEW. How is the averaging implemented in virtual bench softpanel?

It's a modified moving average per point. https://en.wikipedia.org/wiki/Moving_average#Modified_moving_average. N is the value you select in the application (2 averaged, 4 averaged, etc).

Triggering issue

Can you post the VIs you're using for the MSO and FGEN?

Regards,

William Earle

Software Engineer

NI R&D

[Senthilnathan]

Hello William Earle,

Can I access to the averaging code of the virtual bench software?

Thanks,

A Senthilnathan

[WilliamEarle]

Unfortunately, the source code for the application is not publically available.

Regards,

William Earle

Software Engineer

NI R&D

[Seth_B.]

Hi A Senthilnathan,

To re-ask bstreiff's question,  what do you have your pretrigger time set to (on MSO Configure Timing.vi)?

There are usually multiple pre-trigger samples, so it's possible that the acquisition triggered at the zero crossing, but what you are seeing are the pre- and post-trigger samples.

[WilliamEarle]

I wrote a quick LabVIEW VI with a similar averaging  implementation to the application.

Regards,

William Earle

Software Engineer

NI R&D

[Senthilnathan]

Thanks William for the sample code. I have implemented a different averaging method and it works for the application.

To answer the pre-trigger question. I have not configured pre-trigger time. I configure rate, acq time and mode as per the below diagram. Is there any any pre-trigger time/samples by default. If so, it should be constant. I see additional samples when there input signal is at a certain range (above 300kHz or so). 

[bstreiff]

The default acquisition time is 4 microseconds (e.g. 1000 samples at the default sample rate of 250MS/s), and the default pretrigger time is half that (2 microseconds).

If you only set the acquisition time, the pretrigger time will remain at the default of 2 us. Looking at your screenshot, it looks like you have a zero-crossing at 2E-6.

[Senthilnathan]

Streiff,

I set the pretrigger time to 1ns (minimum allowed) and the waveform looks a lot a better. Thanks for pointing out the issue in the code. 

Thanks,

A Senthilnathan