Aquiring more than 2047 samples with PXI-4461 instaled in PXIe-1073

[kuc]

Hi all, i would like to ask you for help with buffer limitation.

I plan to buy digitizer PXI-4461 and instal it in chassis PXIe-1073,i.e. to control it via MXI Express from Labview instaled on separate computer.

What I need:

- aquire data from one AI channel, but at least a sequence of 20 kS per one aquire task, in some situations up to 200kS per one aquire task.

The question:

- Can I aquire more than 2047 samples in one sequence, like 200kS, with PXI-4461 installed in PXIe-1073?

Internal buffer of PXI-4461 is only for 2047 samples. So I am not sure, if Labview program can remotely via MXI Express download buffered data from PXI-4461 via MXI Express fast enough without any affection of the sampling.

- in the case,  that PXI-4461 with PXIe-1073 is not proper combination, which chassis and controller can do it?

Thanks a lot for response

Jan

[gaving · Accepted solution]

This will work for you. 

The 2047-sample onboard buffer is only used as a backup if the data stream to the host PC (via MXI Express in this case) is not fast enough...which it will be (explained below).  DAQmx transfers data from the device's buffer to the host PC as fast as it can, and, in ideal conditions, shouldn't back up the 2047-sample buffer much at all.

Let's just say that you get 110 MB/s (pulled randomly from a MXI data sheet) throughput on your MXI connection.  The 4461 only has 2 analog input channels, which will be 24-bit, which let's just round to 32-bits in case it transfers the data that way,

4 Bytes/Sample (32-bits) x 200,000 S/s x 2 (channels) = 1.6 MB/s which is well below the 110 MB/s which the MXI connection will do.

clear as mud?

-gaving

[kuc]

Thank you gaving, clear as mud