MSO Analog Trigger does not work

[Senthilnathan]

I confifure the MSO for analog trigger for rising edge with value of 0. I have a sinewave connected to MSO channel 1 (trigger channel). I expected to trigger when the sinewave cross 0 from negative to positive. but I see MSO triggered at other places as well. What could be reason for this. How do I get this working consistently?

[crossrulz]

Do you have the Auto Trigger turned on?

[WilliamEarle]

Hi Senthilnathan,

If your signal is noisy, that could explain the behavior you're seeing.

One thing you can try is going to the trigger menu (the "..." to the right of "Trigger" in the windows app) and changing Hysteresis to "Noise Reject".

Regards,

William Earle

Software Engineer

NI R&D

[Senthilnathan]

Auto trigger is off.

[crossrulz]

Then can you post a screen shot of what you are seeing?

[Senthilnathan]

Hello William Earle

I have created my application with the driver APIs. I have set the hysteriss value to 0.01 (my signal's peak value is 0.05) in MSO Configure Analog Edge Trigger.vi. I think this is equalent to 'Noise Reject' option the vitual bench soft panel. Is this correct?

Also I see an option for averaged data acquisition in soft panel, (2, 4, 8 ..... averaged). How do I configure this with driver APIs? Which API to use?

Thanks,

A Senthilnathan

[WilliamEarle]

What voltage range are you using? (This is an input on the MSO Configure Analog Channel entry point).

There is no support for averaging in the VirtualBench API, however it should be straight forward to implement with LabVIEW.

Regards,

William Earle

Software Engineer

NI R&D

[Senthilnathan]

Hello William

Thanks for your help. I use the highlighted vi for configuring. The vertical range is configured with 1.2 times the expected signal. I generate this signal from FGEN of virtual bench and loop back to MSO for measurement (input signal to my device). I assume based on the value I set for limit virtual bench selects the next higer range (like DAQmx). Or should I pass in the specific value to vertical range control to configure the value?

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

- Is it a moving average with the window size? Or Is it over sampled averages like each point in the result waveform is average of N points?

Thanks,

A Senthilnathan

[Senthilnathan]

Hello Crossrulz,

Thanks for your help. Here is what I acquire on trigger with zero crossing. The frequency of the signal is around 630kHz. It looks like MSO triggered in advance. I see this issue in the signal frequency range greater than 400kHz (approx.). If the signal frequency is less than 100k the trigger works good I see the waveform starting from zero crossin of mso/1 channel. I set the sample rate 25 times the signal frequency (coerced to min and max value of the FGEN. I am not sure what mistriggers on certain frequency ranges. 

Thanks,

A Senthilnathan

[bstreiff]

What do you have your pretrigger time set to (on MSO Configure Timing.vi)?