abitrary function generators

[1113562]

Does anyone know if I can set up an arbitrary function generator in signal express?  I want to generate a voltage output that follows a profile against time defined in a user provided array (say from excel).  The hardware is a multifunction DAQ card that has 2 D-A converters.

[Pete.Dunc]

Hi there,

Thank you for joining the forums 

You should be able to do this by following steps similar to the tutorial: Software-Timed Analog Output (DAQmx) in SignalExpress.

• Which hardware are you using?  If this is listed in the NI-FGEN Readme then you will be able to use a NI-FGEN Arbitrary Waveform step.

Let me know how you get on with the above

[1113562]

Hi There, we do not yet have Signal Express but we are debating whether or not Signal Express will do what we need or whether we should go for the full Labview software.  We currently have an old version of Labview and run a 6040E multifunction DAQ card but it is so long ago since it was used the expertise has been lost.  I downloaded a 30 day trial of Labview to play around with Abitrary Signal Functions and did manage to create a VI with a customised signal source that followed values typed into the array for each time step however when I connected this into the dc off set of a DC generator and connect that to a display (i.e. the same set up as the 1st example in the getting started tutorial but replacing the amplitude knob with abitrary source) I could see the voltage changing according to my entered abitrary values at each time step on the left of the graph at time = 0 but the X axis was not progressing across (i.e. I did not get a trace showing historical values and the full waveform).  The display thing has to be me  not knowing how to set this up properly.  I clearly have a lot to learn.  

Thanks John

[Pete.Dunc]

Thanks for your response, John.

The Getting Started with DAQmx series would be a great resource for you to learnt how to code DAQ tasks using LabVIEW.  Specifically there are links to content for Analogue Output tasks at this link.

I would expect this to be possible in LabVIEW SE, however if you want to have a more flexible approach I would personally recommend LabVIEW for development.

[DFGray]

If your output data is evenly spaced in time, doing this in SignalExpress is fairly easy.  Use the import text block (Load/Save Signals»Analog Signals»Load from ASCII) to read your data (should be tab-separated text file, not XLS file - Excel can export this).  Set the timing parameters on the Import Signals tab of this step. Use the DAQmx Generate block (Generate Signals»DAQmx Generate»Analog Output»Voltage) to generate your signal.  Let us know if you need more details.

Note that SignalExpress allows you to synchronize signal generation with signal acquisition; useful for a variety of situations.

[1113562]

Thanks for all this info it is all most helpful

Regards John