Our fastest DAQ boards use the PCI bus, so in continuous transfer, PCI bandwidth becomes the bottleneck of the DAQ system.
Since the PCI bus is 32 bits wide and operates at 33 MHz, we know that we can push approximately 133 Mbytes across it in one second. Our PXI-6115 boards can acquire 4 channels simultaneously at 10 MS/s, where each sample takes up 16 bits on the PCI data bus. Assuming the only activity on the PCI bus is data transfer from the PXI-6115s to host memory, we can compute the maximum number of PXI-6115s allowed before exceeding PCI bandwidth.
Take 133 Mbytes/sec divided by 2 bytes (16 bits) per sample...66.5 MHz. Take that number and divide it by the required 5 MHz/channel sample rate...13.3 channels. Since each PXI-6115 has up to four channels, div
ide 13.3 by 4 channels per board...3.325 PXI boards.
In conclusion, you can use AT MOST 3 PXI-6115s in a PXI chassis with a high speed controller (PXI-8170 recommended). Our small PXI-1002 chassis has four slots available, which would be ideal for this setup; however, since you need 300 channels you will need 25 such configurations!! (300 channels/12 channels per configuration). This is very "doable" if you have the finances.
Finally, if you were to purchase 25 configurations like the one described above, consider using MXI-3 technology, which is in our catalogue to synchronize all 25 systems.
Good Luck!
