problem of acquisition on FPGA mode

[belaji93]

Hello, 

Actually, i am working with Crio 9030 and module c serie 9205 for measuring voltage.

In total, i have 64 channel. so i want to do acquisition of this 64 channels and i am using data fifo to send data from the FPGA to the host (target to host DMA).

My question is how to specify the right size of data fifo ? because sometimes i m getting error due to (data fifo full). 

Also, i think that the rate of FPGA loop can modify my measurement ? 

Also what is the maximal sampling frequency in this case ?  because i am using 64 channels.

I think that my module NI9205 has a sampling freq of 250kech/s. 

thakyou. 

[ArmandoF]

Hello belaji93,

The size of the FIFO is not the only concern: your write speed and your read speed also matter!

I suggest you to check following documentation that might help you:

http://zone.ni.com/reference/en-XX/help/371599P-01/lvfpgaconcepts/fpga_dma_fifo_buffer_size/

http://zone.ni.com/reference/en-XX/help/371599P-01/lvfpgaconcepts/fpga_fifo_using_builtin/

Your module is multiplexed so you have to divide 250 kS/s by your 64 channels.

Have a nice day!

Regards,

Armando

[belaji93]

Hello ArmandoF,

Thankyou for your answer. 

For exemple, if i have a Crio 9030, and two C modules NI9205 (each module has 32 channels). 

In total, i am doing aquisition of 64 channels (two modules). 

Each module can equire 250 Kech/s. 

So in order to calculate the loop rate of my FPGA vi, i need to divide 250 Kech/s by 64 or by 32 ? 

Thankyou so much.

BELAJI 

[ArmandoF · Accepted solution]

Hello belaji93,

You have 2 modules then each one gives 250 Kech/s /32.

Have a nice week end!

Regards,

Armando

[belaji93]

Thankyou so much. 

Have a good weekend. 

BELAJI