frequency response

[nat421]

Hello

I want to calculate the frequency response of a real system, a RC filter.
I use the NI example "frequency_response_(step_response_method).vi", (http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3E6EF56A4E034080020E74861)
in which I generate a slow square wave,1 kHz, with my generator. But the scope don't show me the good frequency reponse of my RC filter.
The problem is that I don't have the approprite Scope-card. In fact I have the PXI-5122 .
Could you tell what I must change that this VI correspond with my card.

Thanks
Nathalie

[SanaaT]

Hello Nathalie,

You can use the example "Frequency Response (step response method)" that you can found on NI Web site :
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3E6EF56A4E034080020E74861

But, you should just do some modification because NI-5122 uses NI-DAQmx and not Traditionnal DAQ :
*** In the VI front panel, in the "resource name" command, type the name of the device (MAX name) and not DAQ::... (please see the help of the function "niScope Initialize")
*** In the diagram, you will see that the example uses digital trigger. So you need to use the connector "AUX I/O".
This is a 9-pin mini-circular DIN connector Provides access to the external digital trigger lines PFI 0 and PFI 1 (with optional cable)
Please see the user manual in the link below :
http://digital.ni.com/manuals.nsf/websearch/998C51E969F4900486256D9F007103F2

I test the program with PXI-5122 and it works well.

Regards,

Sanaa T
National Instruments France