Hello, The DAQPad works such that digital and analog information on its inputs are all converted to software values (stored in something like a hardware register) before being transferred over USB. So any noise on the digital inputs would affect the initial reading of the data. However, after it is read in, the noise does not affect the transfer of data over USB.
I hope that is the case that you are interested in. If not, just write back and tell us more about your connections and the source of the noise.
Regards, John N Applications Engineer National Instruments
I am more concerned about how much noise can be safely added to the USB transfer of data, before the read out of the data at the receiving end is irretrievably damaged. Specifically, what amplitude/frequency of noise would disturb the USB data transfer. thanks Ramesh
Hello, There is no way to directly inject noise into the USB transfer lines unless you opened up the board and wired something to the USB system.
Other than that, USB has a standard hardware interface. If you have motors or other devices that produce strong magnetic fields, they might induce current that could corrupt USB data transfers. Barring that and other environmental noise, you can just depend on the USB standards.
If this isn't what you are asking about, please write back with exactly what you are doing that can inject noise into the USB data transfer.
Thank you, John N Applications Engineer National Instruments