Impact test first steps

[cobayatron]

Hi,

I have done a very preliminar program to perform an impact test. It happens a strange thing here and I am quite sure it should not be difficult to solve, but I'm currently struggling with it.

I attach a capture of the program. It works when I highlight the execution (and by "works" I mean that I obtain a Coherence, Magnitude and Phase plot) but it does not when running at normal speed. (there's nothing in the graphs).

I thought it may be a matter of timing (the loop only executes once) but I've tried to wait X seconds and nothing appears in the plots.

Any suggestion?

Thanks!!!!

[Alexander_Sobolev]

Check the data on the output of daqmx read function. Do you have impact data there? Most probably timing changes when you change execution mode and you read earlier than pulse happens. Pulse search can not find pulse - gives empty data.

Or daqmx read timeouts and does not give data at all. Do you have error after Read?

[cobayatron]

Hi,

Thanks for the interest!

Well, there's no error at all. The Daqmx Read is constantly reading, the trigger selects when to start the whole procedure: plotting the time signal in hammer, plotting the time signals in responses and perform the FRF for each combination of impulse-respponse. If the trigger condition is not met, then keeps reading.

[CarlFHellwig]

Hi Cobayatron,

It is correct that these issues are usually related to timing, as that is changed during highlight execution mode. One way you can debug this application is, as Alexander suggested in his post, to see if there's any data arriving into LabVIEW at all. Try to place a few indicators here and there, and see how the data moves through the program at normal run time.

By the way, what kind of trigger funciton is used right after the DAQmx Read? I don't recognize the icon.

Also, I see that your code has a lot of redundancy: the two case structures have the same conditions and data wires between them (the "Responses" indicator can be placed inside the case), the "Hammer" output is calculated several times inside the For Loop (once outside the loop should be enough), and there is a lot of wires that clutter your code. It is a lot easier to help if you try to make your code look easier to read.

[cobayatron]

Hi,

Thanks for your post. You were right it was redundant in many ways, I've tried to simplify it to make easier to read.

The trigger is a Software Trigger VI (Sound and Vibration toolkit). I've been monitoring data so far and everything seems to work fine. Anyhow, I'll get late today all my  hardware and I will be able to try it properly. I'll let you know how it goes.

[CarlFHellwig]

Hi,

Have you had time to test it out? Any updates?