reset control button after timer expires

[johnspeth]

Hi folks-

I'm a Labview newbie and I'm having trouble find the best solution to this problem: I have an Elapsed Time Express VI which I'm controling with a button (T means start, F means stop).  The user can stop the timer at any time by setting the control button to F.  I would like the button to automatically show F again if the timer expires before the user manually stops the timer.  What LV coding mechanisms should I use to accomplish this behavior?

I've tried using the button value property node driven by my timer-running boolean but it sets the button to one state or the other all the time.  It's state driven.  I need a command driven design, specifically, send a command to the button to reset when the timer expires.  I'm such a newbie that I don't even know what terms to look up.  Please help.

Thanks - John Speth

[johnspeth]

(I'm the OP.)  I stumbled upon a solution but I'd sure like someobdy to explain why it works.  My solution is this:

1. Create a local variable that points to the button I want to reset

2. Wire the local variable to the timer-running boolean

Testing shows it works but I dunno why.  Can someone please enlighten me?

[Hatef.fouladi]

show your block diagram to be make it clear what you want to say

[CAS_MattF]

Think this is what you were requesting.

[johnspeth]

Thanks, Hatef.  I should have done that.

Here's a screen shot of my timer VI.  It is the code in the SysRsrcTimer VI shown after this image.

Here's a screen shot of my code that uses the local variable.  It's only a small part of the app but it covers the discussion topic.

[johnspeth]

Thanks for the VI Matt.  I can see that it's an elegant solution.  One question: Is the shift register bounding the works an essential part of your solution?  I'm not that familiar with shift registers.

[CAS_MattF · Accepted solution]

A shift register is a feedback node that holds the previous state.  This is slightly different version but may be easier to understand.