FPGA Memory

[pabr]

Hi, I’m using LabVIEW RT 7.1 with RIO 1.3.0.  I’m using the following type of RIO devices: PXI-7811R, PXI-7813R and PXI-7831R.

I don’t understand how the 16 KB of available memory is managed.  I guess I can access it all with Memory Read and Memory Write.  But let’s say I have created a FIFO of Block Memory, 1024 U16 and a Lookup Table 1D of 4096 I16.  What happens to my 16KB of memory?  Is it still all available for reads and writes.  If not, how can I know what addresses are not available?

Thanks!

Patrick.

[LittleQ]

You can use them at the same time only if the VI can be compiled successfully, that is the overall cost is under the onboard memory size, for PXI7831R 80KB.

So 16KB is all available for reads and writes.

[LittleQ]

You can use them at the same time only if the VI can be compiled successfully, that is the overall cost is under the onboard memory size, for PXI7831R 80KB.

So 16KB is all available for reads and writes.

[Christian_L]

To clarify the 7811 and 7831 boards have 80 kB of onboard block memory, while the 7813 and 7833 have 192 kB of block memory. This memory is subdivided for different uses such as the Memory Read and Write functions, FIFOs, lookup tables, etc. When one of these components is used in the FPGA diagram, the compiler allocates a part of the total memory for this purpose. The compiler will keep track of the overall memory usage and report an error if you try to overallocate the available block memory.

The Memory Read and Write functions use a 16 kB block of memory by default, while your U16 FIFO will use up 2kB and the I16 lookup table will use 8 kB.

If you do not use the Memory Read and Write functions in your diagram then the 16 kB memory block will not be allocated.

[Doug M]

Also note that prior to LabVIEW 8.2 you had to install the LabVIEW FPGA Memory Extension Utility to get access to the rest of the 80 KB of memory beyond the first 16 KB.

Also, LabVIEW FPGA in particular greatly benefits from the LabVIEW Project and other features of LabVIEW 8 and beyond and I would strongly encourage anyone still developing in LabVIEW FPGA 7.x to upgrade.

[pabr]

😞  sorry, we can't updrade!  We have over 15 PXI controllers deployed in two sites under production 7 days a week, 24 hours a day!  In a year, we'll have over 30 PXI controllers on 3 sites.  We are still adding more systems two these sites and we can't maintain different version of LabVIEW.  After this project I hope to work with the latest LabVIEW!

Thanks!

Patrick.