Operating VIs concurrently

[RickH]

I have a bit of a problem.  I am using 8.2 LV to command a DUT to toggle an output of an amplifier at ~5Hz.  At the same time I am automating a TDS3012, O'scope to capture the waveform and measure the rise time.  So far I have been successful in generating an amplifier output in one VI and executing the Scope measurement in another independently running VI.  The trick is (or question is) How do I execute both of these VI at the same time? 

Details

My signal generator uses frames to establish the correct timing.  I discovered that the scope also requires timed frames on a few of the commands, as I am asking it to do a lot of things all at once and it gets confused.   Hell, I'm getting confussed too.

Anyway, I looked at the execution options, but didn't find anything.  Any help would be appreciated 

 TIA,

Rick H

[tbd]

Hi Rick,

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I am using 8.2 LV to command a DUT to toggle an output of an amplifier at ~5Hz.  At the same time I am automating a TDS3012, O'scope to capture the waveform and measure the rise time.

---

Are you running the Scope VI to arm the scope so that it's waiting for a trigger-condition like a rising-edge, then instructing the DUT VI so the DUT starts toggeling, then - after some time - reading the scope, expecting that it's been triggered and holds a sweep?  If this description isn't right, please describe precisely what sequence of steps you perform to do this manually

Have you tried building a VI where your DUT and Scope VIs are subVIs on the new diagram?

Cheers.

[RickH]

TBD,

I'm using a modified VI to control the scope.  I start the the amplifier toggling in one VI than start my O'scope VI to capture the waveform on a + going trigger.  This is a real show stopper for me!

Regards,

Rick

[Dennis_Knutson]

Instead of two separate VIs, they should be two subVIs (or more) in a main VI as tbd said.

[RickH]

Dennis,

Yes indeed.  Here is the hiarchy of my program:

Main program VI

                  Start toggling on amplifier VI

                                              Capture waveform VI

What I failed to mention is that the program works, but my 240 mS waveform is longer in time.   I am resorting to compensating the time on the toggle for the scope aquisition.  This may affect portability to other test systems, but I'll worry about that later.  In the meantime, if you have any better idea, I'm all ears. 

Thanks again,

Rick  

[Dennis_Knutson]

I don't know what you mean by 'no longer in time'. Is one subVI constantly toggling high and low while another subVI is trying to capture? If that's the case, can't you toggle high, capture, toggle low, and repeat if you need to? Using dataflow between the different functions for the toggling and scope would be much better than having a long sequence structure for each.

[RickH]

Dennis,

What I tried to describe is that my pulse width increases when I attempt to capture the waveform.   I will attempt to restructure my code as per your recomendation.  I really appreciate your assistance.

Sincerely,

Rick H