Event issue: update graph while parameter change

[Pavel_47]

Hello,

Here is setup, I'm trying to realize (please, see the scrrenshots below):

• quadratic equations with 3 parameters a, x0 and l
• a and x0 are controlled by sliders whreas l is controlled by button, that generates random value
• when some of these 3 parameters changes, graph must be updated

I realize this VI using event structure, which has 3 event cases:

• timeout
• either a, x0 or l changes
• button updates l

When a or x0 change, the concept works perfectly, whereas new l value only change indicator, but graph isn't updated.

Where I've been mistaken.

Thanks

Pavel

[Norbert_B]

Your "problem" is that writing a value to l does not fire a value change event. Therefore, your l value changed event will never execute when you press "Generate l".

One option is to write the random l value to l by using a value signaling property node.

Another option is to combine Generate l in l value changed event. That requires some overhead in checking if Generate l was creating that event and then compute a new l (case structure!).

Anyways, please add a stop button and code which stops the loop!!!!!!!!

Norbert

[Bob_Schor · Accepted solution]

When you programmatically change a Front Panel Control or Indicator, this does not generate a Value Changed Event.  To get a Value Changed Event for I, you need to use the Value (signalling) Property for I in your Generate I Value Change case.  Right-click the I indicator, choose Create Property Node, choose the Value (signalling) property, set it to Write, and wire the new value of I into it.  Note that you do not need to wire into I, itself.

Bob Schor

[Pavel_47]

Ok, it works.

Thanks a lot.