LabVIEW

cancel
Showing results for 
Search instead for 
Did you mean: 

FPGA DMA FIFO Channel Count

Solved!
Go to solution

Hey there,

 

in order to understand some problems in my FPGA-VI, i wanted to know, as what I have to see the count of 3 available DMA FIFO Channels:

 

1) The total number of DMA FIFOs created in the LabVIEW-Project

2) The number of used DMA-FIFO-Method-Nodes in the FPGA-VI

 

In case of #1, is there any limit in using FIFO-Method-Nodes, or in placing them in highly interlaced Case-Structures?

 

I experienced some problems in my FPGA-VI, while only using two DMA-FIFOs and accessing them with 3 Method-Nodes in the hole FPGA-VI I got the following error message:

 

There are insufficient DMA channels available on the current target. Too many DMA channels have been requested or some channel requests are conflicting. The current target has 3 DMA channels. Review the list of requested channels and remove one or more to free up resources.

 

So, I searched everywhere, but I didn't found the referred list of requested channels.

I had only created 2 DMA-FIFOs in the project, I only used 3 DMA-FIFO-Method-Nodes in total, and I used only a buffer size of 511 elements in each FIFO.

 

So where can I found the list of requested channels, to see what's going wrong in that VI?

 

Thanks very much!

 

0 Kudos
Message 1 of 4
(2,944 Views)
Solution
Accepted by topic author robal

I believe the limit is the number of DMA  channels referenced in the VI. You can create as many as you want in the project, you just can't use more than three in an FPGA design. Are you using scan mode? That will also use DMA channels.

0 Kudos
Message 2 of 4
(2,928 Views)

Thanks for your answer!

 

Indeed, the problem was, that I was using User-defined-Variables for sharing some process values, and that caused the cRIO to activate Scan Mode and reserve 2 DMA Channels!

How would I know? Smiley Happy

 

Does that list of requested channels really exist, and where can it be found?

 

Best regards

0 Kudos
Message 3 of 4
(2,894 Views)

I don't know of a way to get a list of all DMA channels in use. Many of the documents about the scan engine mention that it requires two DMA channels, for example http://digital.ni.com/public.nsf/allkb/0DB7FEF37C26AF85862575C400531690?OpenDocument

0 Kudos
Message 4 of 4
(2,872 Views)