Capture data at set RPM intervals

[Coryman]

Thank you for responding.

Yes, quite a bit has changed.  My laptop bit the dust last year.  The company sent me a new one, but they have no idea what that means to a technical user who must now built into the new computer six or seven applications with all of the drivers, etc.

I am awaiting the LabVIEW2013 disks from my old company. 

Technical Data:

PCI 6221 DSP Card 

SCC 2345 Front End with 6 ACC001 modules and 1 AC Voltage Module

The system sits at the final test stand in a motor repair shop.  The technician puts two triaxial accelerometers on the test motor and my vi takes spectral data and time waveforms from all six directions and saves them to the job folder at headquarters.  It also calculates the overall vibration from the spectra.  That's what it currently does.

Every now and then a customer will send in a motor that is equipped with proximity probes and a set of proximeters (signal converters with an AC output).  I've researched on line and it appears one can use the ACC001 modules to read an AC input if one turns off the ICP power.  The AC Voltage module will read the tachometer input.

Without the code, I can't even tinker.  The last piece of code (yea, I know.  In LabVIEW you're never really done!), is to save two pieces of information from each probe (4) at 10 rpm intervals during the run down of the motor.  

Magnitude and Phase relative to the tach pulse.  This part has been coded using built up signal generators in LabVIEW and it works well.

So the Case Structure where the data save will occur consists of a For While loop that will initiate upon a user front end button click.  The Case brings in the 9 values and they are connected to a Case Structure inside the For While loop.

My approach this time will be slightly different.  I won't save the complete set of data until the run stops (The For While loop will be wired to stop when the tach input reads 250).  So all of the data will build an array inside the Case Structure until the run completes and then the array will be written into a file.

My biggest hurdle, and I guess I've never really understood how to do it, even with a book on LabVIEW that discussing this in detail, is using multiple Shift Registers to watch the tach input for the 10 rpm decrease.  This is really where I need assistance.

Regards,

Ron Brook

[GerdW]

Hi Ron,

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@Coryman wrote:

My approach this time will be slightly different.  I won't save the complete set of data until the run stops (The For While loop will be wired to stop when the tach input reads 250).  So all of the data will build an array inside the Case Structure until the run completes and then the array will be written into a file.

My biggest hurdle, and I guess I've never really understood how to do it, even with a book on LabVIEW that discussing this in detail, is using multiple Shift Registers to watch the tach input for the 10 rpm decrease.  This is really where I need assistance.

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You only need one shift register to "watch the tach"!

And building an (potentially unlimited) array in a loop is begging for trouble…

[Coryman]

Here is a screen shot of my last working screen.  I will post a png file of my attempts at the 'save data' portion of the vi as soon as I get the application disks.  The two screens on the right illustrate the compensated and uncompensated orbits.  When reading a shaft in a machine, the shaft isn't truly zero, or no runout.  So the slow roll capture saves that magnitude and phase information.  Then after the dynamic vibration is captured the vi does a vector subtraction of the slow roll data from the dynamic data to show the true vibration magnitudes and phases.

[Coryman]

The size of the array will be strictly limited because only one set of data will be captured and that is based on the tach reading having dropped 10 rpm.  It will sit there and wait for the rpm to change another 10 rpm before capturing the next set of data.  So, no.  There isn't any danger of overflow.

Glad you are still 'out there'.  I will send you my 'best guess' once I load up the application.

Regards,

Ron Brook