what is the maximum sampling rate for digital input in PXI 7831R?

[keyur.ospl]

hi all

i would like to know what is the maximum sampling rate for digital input in PXI 7831R in windows environment.

plz send me the answer

thanking you

keyur makadia

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[Oswald_Branford]

Hi Keyur!

According to the specifications datasheet, the maximum rate for analog input is 200KHz and the maximum configurable rate for the high speed digital lines is 40 MHz.

You can check the specs for this device in the following link:

http://www.ni.com/pdf/products/us/2005-5528-301-101-D.pdf

I hope this helps, have a nice day 🙂

Oswald Branford

[keyur.ospl]

first of  all thanks

by the way i just wanna know that how much exactly i can get maximum sampling rate not as per specification

thanking you

keyur makadia

[Coal_Man]

Keyur,

Although you can get internal clocks on the FPGA to run at higher speeds (>100Mhz), the digital I/O terminals cannot run more then 40 Mhz.  If you are needing to sample digital input at a rate higher than this, you may want to check out our high speed DIO devices that can get up to 200MHz sampling rate. 

I hope this helps.

[keyur.ospl]

hey brian thanks for answering my question?

in my application i got 1.66MHz sampling rate in windows environment right

so can you just tell me how maximum i can get ? not as per manual

thnaking you

keyur makadia

[Coal_Man]

Keyur,

I see, so you are not seeing the sampling rate that you want on your board.  Your sampling rate is going to depend on how you have your code set up.  Are you doing any analysis on the samples while acquiring or are you just streaming them to disk to analyze later?  Is your acquisition inside of a single cycle time loop to ensure that a sample is being taking at each tick of the clock?  It would be helpful if you could post the code that you are using to do the analysis.  It would give me a better idea of why you are not getting the 40MHz sampling rate that you need.

Ideally, you would have the clock on the FPGA set up for 40MHz, and inside of a single cycle time loop you would acquire from your digital output and save it to another location, while doing the analysis later.

[keyur.ospl]

Thanks brian

in my code i just acquire 1 digital port input but probem is that i am getting only 1.66 mHz speed. i think if do you have any code that acquire 40 mHz speed in digital port input that will be helpful for me, ,u exactly idea to prove that the the NI PXI 7831R will acquire 40 Mhz speed.

once again thanks for reply

keyur  makadia

[Coal_Man]

Keyur,

Your code should look something like the picture I have attached.  It will be a single digital line read inside of a single cycle timed loop.  Everything within the loop will happen within one tick of the clock, and with the clock at 40MHz, you will be acquiring at 40MHz.  I hope that this helps.