Sample Delay VI

[Alantino]

Erm.... yes i know that there is a subvi name sample delay.vi but where can i find the file to attach it? Sir, why don't u do an example for me? the example can be simple with just a analog input and delay it by 10ms then send to a analog output. waveform chart can also be use to show the signal before and after the delay. Thanks. Regards, Alan

[mikeporter]

All you have to do is double-click on the icon in the block diagram. This will open the subVI's front panel. Now select Save As... from the file menu, this will show you the location of the file.

Mike...

[Alantino]

Hi mike,

thanks for the advise, finally found it!!

[Juan G]

Hello, 

Can you add a constant of 1000 to it will wait 1 second inside the output loop?

Juan Galindo

[mikeporter]

When you run your application what value are you supplying for the delay value? Accoring to the Sample Delay VI's help screen, the delay is specified in number of samples.

Mike...

[Alantino]

Hi juan, are u talking about the sample delay vi or the wait vi?

[Alantino]

Hi mike,

I had my analog input sample at 48khz, so for a delay of 1sec i should delay the sample by 48k times. i'm i on the right track?

[mikeporter]

Yes, you should delay by 48,000 samples. If that's not working, I would say we need to hear from NI how this is supposed to work (it looks like it's a VI they wrote).

Mike...

[Alantino]

i just mail NI, hopefully they will reply me soon. Wonder is there any other method i can try. I tried the wait.vi but i cant connect the wait.vi output to my analog output

[mikeporter]

Actually, you could try building a delay function yourself, the concepts aren't very hard. You need to create a stack (a FIFO buffer really) that has the same number of elements in it as you want to delay. In your case, you want to delay the output by 1 second and you are sampling at 48000 samples per second, so you would create a buffer of 48000 elements.

You then start inserting data into this buffer as it is acquired. When the buffer gets full (contains 1 second of data or 48000 samples) start shifting data out of the buffer as necessary (oldest data first) to make room for the new data you have just acquired. This data that gets shifted out is your output.

The only tricky part is managing the array manipulations such that you aren't constyantly allocating and reallocating large chunks of memory.

Mike...