generating a custom signal through a simulated device

[jt_04]

Hello,

I am acquiring 6 channels of strain gauge data simultaneously through the SCXI-1000 chasis with the SCXI 1520 card.  I want to create a synthetic input signal so I can test my programming structure.  I created a simulated device and simulated channels, but I cannot figure out how to control the simulated signal that is being generated.  I would like to be able to specify a waveform, frequency, and amplitude of the simulated data so that I can test some special cases of my application.  i cannot use the 'simulate signal' subvi because my code needs to remain unchanged to truly test this.  please let me know if this is possible through a simulated device.  your help is much appreciated.

thanks,

jt

[MechEman]

Hi jt,

Simulated devices only input a sine wave.  This is just to test to make sure that you can read and write from your card appropriately.  If you want to test the functionality of your code, you can replace the data acquisition portion of it with a Simulate Signals Express VI.  This should do more along the lines of what you are looking for.

Good luck

[Wayne.C]

jt,

Functionality of the Simulated Device is very limited and not going to meet your needs.  Any chance you can get your hands on a SCXI card that can output analog signals?  You could then just write an application that generated the kinds of signals you needed. 

Another thing I've done in the past is to use an o-scope to capture waveforms and then transfer them to an arbitrary waveform generator.  I have also built custom hardware to generate signals.  The best solution really depends on your situation an the kinds of stuff you can readily get your hands on.

[jt_04]

Thanks for all the help.  I will look for another way to generate a simulated signal.  Maybe a future version of Labview will have the capability to control a simulated device.  🙂

[johnsold]

jt,

You can write your own simulated signal source.   Make a copy of the DAQ Read VI with a different name.  This gives you a VI with the same connector pane so it can be substituted into your program.  Open the simulation VI and remove all of the DAQ stuff.  Put your simulation code in its place.  Substitute the simulation VI for the DAQ Read VI in the main program.

Now, how do you "specify a waveform, frequency, and amplitude of the simulated data?"  

You can add a cluster with controls for all those variables to the connector pane if there is a terminal available. Or you can use an Action Engine.  Call the action engine with the command set to Write in your setup code or in a separate VI for the purpose.  Inside the simulated DAQ Read VI call the AE with the command Read to get the parameters for your simulation.  Your flexibility with this approach is limited only by your imagination and your coding skills.

Lynn