Pascual,
I believe that your thinking is correct. I have used at least 3 6070E modules in exactly the same manner, saving 16 channels at 100Ks/sec.
With the PXI chassis, you should only need one while loop, because you can simultaneously start each of your 6070E's by using the built-in RTSI timing bus in the PXI backplane. This means you will be able to set up each of your acquisitions and set them to start on a trigger pulse, and trigger them all with the same start trigger.
Your limiting factors will be two: 1) does the PCI bus have enough bandwidth to get all of the data across the bus and into the computer memory; 2) can you write all the data fast enough to the disk to keep up.
On the latter, keep in mind that it is MUCH,
MUCH faster to save the raw A/D values than it is to use engineering units. If you try to use EU, you'll use up too much CPU time. If you use virtual channels in Measurement and Automation Explorer (MAX), it takes too long for it to calculate the EU and return them to LabVIEW (if you're using LabVIEW) at these speeds.
So, first I would try to scan these 40 channels and see what happens. Don't try to write them at first--just see if the PCI bus can handle it.
Then, try saving one of the boards' data to file. Then the next, then the next, etc. Don't try to read too much data or too little data every loop--I've had to play with it to see if maybe .5 seconds works best, or .25 seconds.
Hope this gave you some ideas. Let me know if you need more info.
Mark
