Using USB NI-6363 for hardware re-triggerable analog trigger signal(APFI0)

[Hasham622x]

Hi, 

sorry for the late reply.

I also want to add that using a sine wave as an analog trigger can cause unreliable triggering because the signal crosses the trigger threshold gradually and repeatedly near zero voltage. This leads to multiple false triggers due to noise or small signal fluctuations. In contrast, a pulse or square wave has clean, sharp edges that produce clear, stable trigger events.

I would like to ask if it is possible to use the analog output channel (AO0) as a trigger signal. If so, could you please guide me on how I can configure and utilise the AO channel as an analog trigger source?

Thank you for your support.

kind regards

Hasham

[Hasham622x]

Yes, I tried using Dev2/ai0 and Dev2/ai1 as analog trigger sources, but the code is not running.

[Kevin_Price]

Several things, briefly:

1. Up in msg #18 you posted multiple pics of a scope screen but with no explanation of what you were trying to show us.  Where are the various signals (square, sine, triangle) coming from?   Are they being sourced from the same function generator?

    I can see that the square wave transitions are closer to the true 0-crossings for the triangle wave than for the sine wave.   But *visually* at least, it looks pretty consistent.  And I don't see the connection to this thread's discussion about your DAQ device's analog triggering behavior.

    What are we supposed to understand from seeing those pics?

2. Considering those clean sine waves, I also don't understand the following comment:

...using a sine wave as an analog trigger can cause unreliable triggering because the signal crosses the trigger threshold gradually and repeatedly near zero voltage. This leads to multiple false triggers due to noise or small signal fluctuations

A sine wave doesn't idly "hang around" near zero.  What are the level and hysteresis settings when you get multiple false triggers?
What have you observed from trying a much wider range of trigger settings (level, hysteresis, other analog triggering modes)?

You seem to be concluding that the analog trigger circuitry of your DAQ card is not very repeatable.  I'm resisting that idea (at least initially) because if true, there should be a lot of ongoing complaints around here about the same issue.  And I haven't seen that.  (Granted, it's possible you have a specific single DAQ card that behaves differently than nearly all the others.  I just don't consider that the most likely scenario barring a lot more convincing evidence I can clearly understand.)

3.

I would like to ask if it is possible to use the analog output channel (AO0) as a trigger signal. If so, could you please guide me on how I can configure and utilise the AO channel as an analog trigger source?

I'm really confused about what you'd hope to accomplish with this.  Is this just to test the analog input trigger circuitry?

4.

I tried using Dev2/ai0 and Dev2/ai1 as analog trigger sources, but the code is not running.

What kind of "not running"?  Were there errors?  Was there a timeout from failing to see the trigger?  Can you post the "not running" code?

-Kevin P

[Hasham622x]

Hi,

Response to #1:
Yes, I shared oscilloscope images to show that the trigger works correctly when the waveform is triangular or a pulse (square), and the input signal is a sine wave.

Response to #2:
Based on my observations and the captured data points, it appears that when using a sine wave as the analog trigger, the DAQ is not capturing the point exactly at the trigger event. This seems to be causing the transient behaviour I'm observing.

Response to #3:
Yes, I would like to try using the analog output (AO) channel as a trigger source, since it can generate a pulse signal.

Response to #4:

I attached code.