How to stop measurement at some conditions (6120)?

[Maksoff]

Hello!

Now I'm working with ni 6120 board, and have a problem.

I need to start measurments after trigger, and I should stop measurments after fixed number of sinchropulses of after analog edge trigger. But it seems, what i can only stop measurments after fixed number of sinchropulses.

Also i want to create output signal of TTL level (5Volts) for fixed number of sinchropulses, but i should to disable it after analog edge trigger. Can i do it by software, or, maybe with some additional hardware?

I'll be happy to see any idea!

[Christian Mergl]

Hey,

Are this "Sinchropulses" an analog signal or TTL?

Christian

[Maksoff]

Sinchropulses are external clock source, TTL.

[Maksoff]

And i need to sample measurments with frequency 100kHz-300kHz.

Maksim.

[Christian Mergl]

And the Start and Stop Trigger are Analog Edge Triggers?

Christian

[Maksoff]

So, in LabView I found only Start trigger and Reference trigger.

It is clear for me how to manage start trigger, but i didn't found Stop trigger at labView at all.

For my purpose I need Stop Trigger with trigger type - "Analog Edge".

Generally my task is:

Using ni6120 board, start measurments, generate TTL level on output (Analog output, or digital output, no matter) after 10 000 (for example) clock sources (external clock source), OR after the voltage on input reaches the treshold I need immediately to disable TTL level on output and stop measurments.

Thank you for your assistance!

 Maksim

[Christian Mergl]

Hey,

The problem is that your hardware supports analog triggering only for a start trigger.

You could create an external circuit which converts the analog signals to digital signals for the card.

It might work using a 6251 M-Series card which supports analog reference triggering, which means after a specified analog trigger you can view a certain (also specified) amount of pre trigger samples. This could be done in combination with an external clocked finit measurement.

Anyway I'm not 100% sure about that so I would suggest that you contact your local NI Office with detaild specifications about your application to get a suggestion about what hardware fits best.

Christian

[Maksoff]

Thank you, now i'm doing hardware circuit to do my task.

Can you explain me, how works reference trigger, because it is hard to understand for me. It stop the measurment then it acquires fixed amount of samples or until the trigger?

Thanks a lot!

[Christian Mergl]

How the Reference-Trigger works is described in the DAQmx help.

Christian