Triggering

[Soran]

Hello all,

I have a sine wave coming from a function generator and can see it in LabView by DAQ assistant. Would any one please tell me how can I trig the signal? I mean, can I make the signal stable just like a oscilloscope?  Is there any special command (Vi) in Labview that tigs the signal?

Thank you

[Frisbee]

Hello Soran,

Thank you for posting on the forums. What piece of hardware are you using to acquire the sine wave created by your function generator?

Typically, we use triggering as a launching point to start acquiring data or outputting data, as seen in the White Paper linked below:

“Tips and Techniques in Data Acquisition Triggering - NI-DAQmx”

Could you please provide screenshots of the behavior you are seeing and a description of what you would like to see?

[Soran]

Hi Cameron,

Thank you very much for your reply.

I am getting the wave by a DAQ card PCIe-6351. I have attached a screenshot of my code. As you see you can see Waveform Graph shows the wave (in this case tiangle). This wave is moving and I want it stable (just like when an osciloscope is used and we trig the signal).

Many thanks

[Frisbee · Accepted solution]

Hello Soran,

Based on the code in your block diagram, the Waveform Graph is updating continuously as it reads the data generated by your DAQ Assistant in every iteration of your While loop.  This configuration can provide a “stable” waveform in your Waveform Graph if the data you send it remains the same as your loop continues to iterate. For example, the snippet below displays a sine wave, and the waveform graph appears to display the same waveform over time because the input data does not change between iterations:

Additionally, the sampling methods you are using are an important part of acquiring your data- and thus impact how that data displays. Could you please post your VI so we can take a closer look at how you have configured your DAQ Assistant?

[Dennis_Knutson]

You are also using the run continuous mode and that is just wrong. You need a while loop.

[Soran]

Cameron,

I do appreciate your helpful message.

I have attached the code that I am using. I get the data from an optical detector. I used to use an oscilloscope but now I should process the data by LabView that is why I should make it stable.

Thank you very much