FPGA The fastest Analog output? (RIO 9641)

[togoto]

Hi everyone!

I read that analog output have about 38 tics. clock 40 MHz (RIO 9641) 
My RIO gives me analog output 107=112-5 tics for 1 iteration. If put DAC in cycle.. Whole cycle takes (112*160*25e-9) for DAC 107*160*25e-9=428e-3 sec. Whole time takes DAC, and i need faster.
How can i set up analog output faster or rebuild programm? 

I need the fastest analog output, is this possible?

Thanks for help!

[NukeB]

Hi Togoto,

You said that you needed the "fastest" analog output available.   How fast are you hoping to get new values updated?  As fast as possible isn't really a thing.  If you want absolutely as fast as possible, you should be using different hardware, so if you could clarify, that would help.  You are correct that the DAC (also ADC's so you know) is going to take ~40 ticks (depends on the the module) to output if you are using a cRIO/sbRIO/R Series DAQ device.  But I don't think that is the problem you are seeing here.

From the looks of that loop below, you are only outputting on AO1 every 160 iterations of that while loop.  Its hard to tell exactly what you are doing in this code, because you are just writing to a FIFO with tick counts, and reading from memory, but only using the memory locations that are at address 160.  Can you better explain what you are trying achieve?

[togoto]

Thank you for answer!

I need analog signal with high velocity from my memory which has 160 elements.

In that program ADC's AO has time about 107 tics. Whole cycle has 107*160 tics. i need 40 tics(minimum) for ADC, how can i do this?

[Dave.C · Accepted solution]

Hi togoto,

Please let me know if I'm misunderstanding what you're trying to do, but the fastest the analog output of the 9641 can update is 120 ticks per update.  That is based on the hardware specification on page 44 of the User Guide and is the limitation you're hitting.  As a result, I don't think you're going to be able to get it down to 40 ticks. 

[togoto]

you are right Dave C !!

my fail, I need read more carefully

Update time
One channel in use...........................3 μs

thank you for help!