Digital sampling on PXI-7851R

[Gael B]

Hello,
 
I would like to have your help on an issue I have using a PXI-7851R.
I tried to acquire 48 digital signals at 1Mhz with this card.
 
Using project wizard, I succeed to get a working acquisition vi (Using a DMA FIFO to pass data from PXI-7851R to PC), but it seems to be limited at nearly 100kHz, which do not change with number of input.
 
But, as far as I understand the Datasheet, digital acquisition may go as high as 40 Mhz.
 
Where am I wrong?
 
Thank you,
 
Gael

[R_Duval]

Hi Gael,

Could you give more details on your application/configuration?

I don't think the limitation at 100KHz comes from the PXI 7851R that's why I need to know what you want to do exactly.

Thanks in advance for you feedback.

Kind Regards,

[Gael B]

Hi Romain,

I have a PXI-1042-Q on which I use (for this application) the PXI-7852R (sorry about that, I have indicated that I have 7851R). Host computer run LabView 2009 with FPGA module, on WinXp (no RT kernel).

So,
I do a LabVIEW FPGA project of 'R Series Intelligent DAQ on My Computer' type.
Then, with FPGA wizard I add one 'Buffered DMA Input' to which I add one connector (Connector1/DIO1).
I set clock setting of Buffered DMA Input to 10 MHz, internal clock type, with 40000 samples (to get 4ms of signal into the buffer)

I open project, go to MyFPGACode.vi push play to let labview what it has to do. Everything is correct and I get no error.

When finish, I start MyHostCode.vi and 'Buffer Underflow' light on. If I go down to 1 MHz in 'Loop Rate', it works.
What I try to do is to record digital signal from a connector to let me check communication between two parts of a system. This connector has 50 pins, 48 signals and 2 grounds. I would like to acquire at least at 10 MHz (I am not sure that I have to go that high) with all the 48 pins at the same time.

I enclose a dummy project I made with a single connector.

Thank you for your help,

Gael

Message Edité par Gael B le 01-18-2010 06:16 PM