Locking one slide position based off another

[athiggins]

I'm trying to make a slider with two position markers (A & B).  At certain times I want A & B to be completely independent of each other, but at others I want slider B to be controlled by slider A.  For example, when I want them locked together I want B = A + 2.  I know how to get the value of sliders A & B from a property node, but I can't figure out how to set one without setting the other an/or freezing. Any ideas? Attached is a VI snippet and the VI itself.   Thanks. 

[aputman · Accepted solution]

Put the code inside the while loop into an event structure in a value change event for the slider.

[aputman]

You can also add a small 10ms delay in your code to slow down the execution. 

[altenbach]

• You are not getting any values from a property node, you are setting values.
• A local variable here would be much better than a value property node
• If they are locked, you should be able to move either A or B.
• Your set control should be I32, not DBL if the rest is all I32.

Yes, create an event structure for slide value changed, see which one changed, and update accordingly. There is no reason to spin the loop millions of time/second if nothing changes.

[athiggins]

Hi Aputamen,

I've never used Event Structures, and the LabVIEW help isn't being terribly helpful... Do you mind showing me?

Thanks

[athiggins]

Sorry, 20 minutes of futzing and I found it.  Thanks!

[aputman]

"Futzing around" is the best way to learn, IMHO.

[altenbach]

There are a couple of things that you should keep in mind. For example, make sure to limit the even queue size to one and don't forget an event for the stop button. Also use a local variable instead of a value property, use the correct representations, etc.

Feel free to attach your code for a second look. 😄

[athiggins]

That would be great!  The slider changing bit is part of a larger code for a vitals monitor.  I'll polish the code, gather some sample data, and send it your way tomorrow when I'm back at work.  Thanks!

[athiggins]

Here is the larger code the slider bit was shoved into.  The slider can be found in the "Analysis" mode.

To test the acquisition mode, be sure to select the "Simulate?" option on the top, else you will get an error saying the DAQ box isn't connected.  

Attached is the VI and some test data for your perusal.  Please feel free to critique my work.  Any suggests will be appreciated.  Thanks!