CRIO 9024 works with 4 9234 modules

[Wenxu]

Hi there,

I am using CRIO 9024 with 4 9234 modules. When I run the modules at the their max sampling rate, i.e. 51.2 kHz, the signal (at 1kHz given frequency) does not have the principle component at 1kHz. Whereas when I tried a few other lower sampling rates,from 10,24kHz to 25.6kHz, all of which are supported by the 9234 module, the signal did have a dominant 1 kHz component.

I would like to know what could be the reason? Is there a possibility that 9024 does not support 4 9234 modules to all run at their max rates.

Regards

[DahlmanR]

In terms of how much/how fast data can be transferred between the FPGA and the RT, you should be okay. 

There is a note here in the C Series Module Compatibility Chart that notes that
" Modules designed for sound and vibration signals use an onboard, high-speed timing source. Accessing one of these modules using the Scan Mode Interface for CompactRIO severely limits the frequency input range and may cause higher frequency signals to alias. The LabVIEW FPGA Module is recommended for sound and vibration measurement with CompactRIO." 

Are you using Scan Mode Interface? If so, you may want to consider programming the FPGA. We have an example and help documents on working with the 9234 in FPGA. 

Acquiring Data from an NI 9234 (FPGA Interface) : http://zone.ni.com/reference/en-XX/help/370984T-01/criodevicehelp/9234_reading_data/