use ni myDAQ to scan the voltage

[hxw]

Hi, 

I am using the NI myDAQ to scan AC voltage from 0-10 at 1kHz, the file is attached. For each voltage amplitude, we maintain the amplitude for 1s. We noticed that there is a gap between different voltage amplitudes, see the attached figure grabed from the oscilloscpe. The gap time is about 20ms. We are wondering if the DAQ board itself can not work in this way with a loop. Thanks. 

[Alexander_Sobolev]

See

Cont Gen Voltage Wfm-Int Clk-Non Regeneration.vi

from ni examples (menu -> help -> find examples)

[hxw]

Hi, 

Thanks for your reply. I do not know what you mean. I tried to use the key word: Wfm-Int Clk-Non Regeneration to search in the help but I can not find the answer. I also used Clk-Non Regeneration to search and I still can not find it. Could you give me some info? Thanks. 

Huihui 

[nyc_(is_out_of_here)]

maybe https://decibel.ni.com/content/docs/DOC-3545 will be useful

[Dennis_Knutson]

Why are you searching the help file? You were told to look in the shipping examples.

[hxw]

Thanks. I got the example. 

[hxw]

Hi, 

Thanks for your help. I can solve the time gap problem with the file in the shipping examples. However, I had another problem again. I changed the program a little bit to try to maintain the loop for 1s. It shows the error in the attached file1. Also I attached another file of the block diagram to demonstrate the change in the program. I marked the change in the circles. It seems a hardware problem. I used NI myDAQ and NI USB-6259 both but it shows the same error. Could you tell me if it is the hardware problem or the software problem? Thanks. 

Huihui

[Alexander_Sobolev]

No, it is not hardware 😃

You generate 5000 points at 20000 Hz rate. It takes 0.25 s to generate them all. You wait 1 second before writing new data. It has nothing to do for 0.75 s - it does not regenerate data. You have to provide new data before end of generation - that is why example did not have any delay. The timing is determined with size of data and sampling rate. 

Change amplitude every 4 iterations. The function generator vi provides constant phase between iterations.

[hxw]

Thanks. Yes, it works.