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Re: Have an idea for new DAQ hardware or new DAQ software features?


I've been using NI  PXI 4461 data acquisition hardware mainly to realise the DSA(dynamic signal analyser) functionalities. While the hardware supports both analog input and output, it is not sure whether both can be used simultaneoulsy. It would be useful if information is available on this.And when i tried to to use both the functionalities, i.e to generate a signal and acquire the same in one of the 2 analog input channels(with sample clock option in the daqmx timing ) , error is generated. could anyone please clarify as to the the sampling options available if i have to use both the functions simultaneously which is required if i want to carry out frequency response measurements.

Thank you


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Hi kavyashree,


If I understand correctly, you were trying to generate an analog output signal with the PXI-4461 to then read back in from an analog input channel.  This module should be able to use analog input and output at the same time.  Can you describe the error that you received?  There may be some other reason why your setup wasn't working.


Jared R.
Precision DC Product Support Engineer
National Instruments
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Hi Mr Jared..

Thank you for the reply..

I found out how to do it , i mean, how to generate as well as acquire simultaneously. Mistake was with the way i had written the code. Now that this problem is solved, i am faced with another problem. I am trying to generate random noise using 4461 card.The basic function generator vi and also the 'create signal' vi(from signal express), doesnt provide the option of random noise( create signal vi gives only Guassian noise). so, i added one more case to the case structure in create signal vi, where it generates periodic random noise, using the 'generate prn waveform' vi. the generation is ok. But i am not able to get the  input as expected to my unit under test. Till now, we used to give input from Agilent series DSAs, which can give random noise source output. With the random noise generated from 4461 card, the response from the unit is not good to say. but with guassian it is ok.could you please suggest something regarding generating random noise from 4461 card??


and next is. plotting frequency response. If i use the 'frequency response' express vi from 'signal express' menu, i am not able to give inputs to it(even after converting it to a subvi). and with the 'FRF' vi, ie frequency response function vi, the waveform is not smooth even after averaging. the averaging doesnt seem to be having any effect..

Kindly refer to the 'dsa code' vi(main vi) and 'subvi copy' for the subvi created out of 'create signal' express vi.. Plz dont mind the haphazard wiring. i still need to arrange that...  


Thank you


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