Adding a step response function, and a sinusoidal frequency response to the same file

[viksen]

I've looked about, and been trying to do this for weeks, but getting nowhere despite it probably being really basic. : (

I have a DAQ board AD/DA setup on the block diagram, with a graph plotting error vs control output, however I currently have to alter the control output setting myself.

If anyone knows how I coudl add a step input function to this, and a sinusoidal input function, so I could see the respective step and frequency responses, I'd be extremely grateful.

I can attach/send the VI file to anyone who could possible help.

Much thanks in advance.

[TheWay]

Hi there,

I would be happy to help you.  It sounds as though you are trying to do a simple loopback by generating a signal on a channel and then acquiring it back on another channel and analyzing it. Can you please attach the VIs to your post so I can view them?

Also, what DAQ board are you using? Are you using DAQmx? There are some simple DAQmx generation and acquisition examples in the NI Example Finder.  A good and simple example would be Cont Gen Voltage Wfm-Int Clk.vi for waveform generation. Take a look at that and let me know if you have any questions.

Way S.

NI UK Applications Engineer

[viksen]

Thank you very much for the response.

I'm a beginner at this, hence I'm finding it all a bit tricky.

My DAQ board is the PCX-2026A, and I have attached the VI as requested.

I'll try and also have a crack at what you said.

[TheWay]

Hi,

I've tried to open your VI but since I don't have the PCX-2026A board or its drivers, I can't see any of the function VIs in your VI and won't be able to replicate your problem. Even so, from looking at your code, I noticed that the DA output control is not connected to your 2026_WriteDA.vi.  Although I am not familiar with the 2026A, it would make sense that control should be an input to that VI if you want to continuously change the output voltage.

Way S.

NI UK Applications Engineer

[viksen]

Thank you for the response.

I was just wondering if there was any step by step way I could see how to add both the frequency and step responses, that you know of, as you can't access my file properly.

I'm pretty much a beginner at this. 😞

Thanks again.

[TheWay]

Hi,

I did a quick search on the net for LabVIEW code examples for the PCX 2026A, but didn't come up with anything concrete. Unfortunately, I have no way of writing my own code since I do not have the same hardware as you.  That usually is the problem with third party boards.  Maybe you can contact the manufacturers and see if they can give you LV code examples that would help you.

Regards

Way S. 

[viksen]

I think I'll try using the Cont Gen Voltage Wfm-Int Clk.vi. I've found it and was just wondering how you suggest that I integrate my present file with it, as I was previously using daqmx.

Thank you

[TheWay]

Hi,

Do you mean you are trying to rewrite your code to look like the DAQmx example?  You won't be able to use the DAQmx example with your third party card, since they use totally different drivers. I thought you were using a NI DAQ board in the beginning, thats why I recommended using that example.  

Way S. 

[viksen]

Ah I see. Do you suggest any other ways I could get help on this?..

[TheWay]

Not that I know of.  I looked at the manual and it was not that helpful either. 

Way S.