Digital waveform write to DAQ

[tintin_99]

HI Marius,

I have seperated the DAQ creation from DAQ write. On my system it takes about 7ms to write data ( Write a digital waveform with 4200 lines ( number of samples ) and write data to 16DAQ lines in parallel)

I still don't understand why it takes 7ms or even 2ms. I have 4200 samples and I write at 10MHz so it should take about 420us top write the data. Is there a difference between digital waveform and normal numeric array in terms of size?

Thanks

[Dennis_Knutson]

Why don't you lookin at the output waveform with a scope? I'm certain that the actual time between samples will be exactly what you expect. The time to load the samples and start the task is NOT the same thing as your sample rate.

[tintin_99]

Dennis

yes I measured it . It is exactly what I expected

I need to write multiple times. Is there anyway to load samples all at once ( maybe buffer them ) and then write multiple times? How much usually is the start time?

[Dennis_Knutson]

How many samples? Are you using continuous generation?

[tintin_99]

It is finite number of samples. Let's say I want to write 4200 samples 10 times .

Can I craete the task, set timing, buffer 42000 samples and then write 4200 samples 10 times and after each write I close the task

finally clear the task?

[tintin_99]

I tried that actually. Not multiple times but just 1 time

It didn't help. I completely removed the timing VI+buffer the sample VI and just left DAQ start+write to DAQ+ stop DAQ

It still takes 7ms to complete and write 4200 samples 

[Dennis_Knutson]

If you want to write without delay, I believe you need to use continuous update. You can terminate a loop after x iterations and you don't want to clear the task after each write.