Fast response to analog output change

[CHartman]

Hello Community,

I have the following problem (I'm using a myDAQ):

I want to generate an analog output signal, depending on the user input and measure the same signal with an analog input and this to be displayed on the front panel.

Now I recognize a delay between the user input and the measured signal, which is about 10 seconds.

I checked the analog input side with different external signals and I’m sure this is not the problem.

So I think it takes a huge amount of time before the new values are written to the analog output.

I also tried to allow regeneration and write new values in the buffer, but I get nearly the same delay.

Is there a solution to decrease the time between user input and analog output?

Kind Regards

[Dennis_Knutson]

What user input? The amplitude and frequency? What sample rate and number of samples do you specify?

[crossrulz · Accepted solution]

---

@CHartman wrote:

Now I recognize a delay between the user input and the measured signal, which is about 10 seconds.

---

I'm guessing your sample rate for the Analog Input is 10Hz.  This would make since since 100 samples would then take 10 seconds to gather up.  Either increase your sample rate and/or decrease the number of samples you are reading at a time.

[CHartman]

Hello and thanks for your reply,

the user should be able to change the frequency, amplitude and form of the output signal.

I already found a way: I increased the frequency of the analog output, thereby the buffer could be read / refreshed faster and changes in the output signal were faster transferred to the analog output. Secondly I tried to do the same with using regeneration of the buffer to decrease the bus load.

But I figured out, that I’m limited in the signal frequencies. For example: If I’m using a frequency around 100 kHz for the analog output and a buffer size of 1000 the lowest signal frequency is around 100 Hz.

Is there a way to change the output buffer size or frequency while the task is running?

Kind Regards

[Dennis_Knutson]

If you set it to the max sample rate of 200kS/sec, you should be able to output a nice 20kHz sine wave.

http://www.ni.com/tutorial/11503/en/

[CHartman]

Hi,

the ELVIS program looks great and has fast response to the user input. How do I get the LabVIEW code from the ELVIS function generator?

Kind Regards

[Dennis_Knutson]

http://www.ni.com/download/ni-elvismx-15.0/5424/en/

https://decibel.ni.com/content/community/academic/products_and_projects/mydaq

[CHartman]

Thanks a lot.

I figured out, that the myDAQ is the problem.

If I'm using a PCIe 6353 card to stop and restart the task it taks around 1ms in contrast to 1-2seconds on the myDAQ with the same LabVIEW code.

Kind Regards