How to get controls of a vi to send signals more than once

Question

Hi,
Recently I designed a rather neat VI that allows the user to quickly switch wiring and ID number characteristics on a certain device.  The inside of the VI is an orchestration of sequences and loops that allows user full control through one control loop that cycles through until the user selects a desired function, for which the loop terminates and performs the function.  After the function is complete, if the user has not pressed "stop", another loop brings the program back to the control loop.
So the VI works great, but as someone who's been interested in automation, I want to try to take this to the next level.
My next attempt was to put the finished VI as a sub-VI in a new VI that is meant to automate the user control process on the front panel.  I've attempted to use both a flat sequence and the state machine template to do this, and they work great for automatically pressing buttons when working with property nodes or local variable.  The problem, I've found, is that I don't know how to send signals to the Sub-VI from the connected controls at a constant rate without throwing it into a loop itself, which doesn't work because, of course, the sub-vi runs on it's own set of loops and there will be no iteration increment until the program inside the sub-vi terminates.
Or, if the VI and it's inputs are left on it's own and I try to write values to the controls of the inputs, I can definitely change button positions, but, looking at the signal flows, no signal will be sent from the connected controls to the sub-vi.
A second problem is that, due to my use of a program button that latches when pressed, I'm having a tough time trying to manipulate it will local variables or property nodes.  Because of the way it functions, the "value" property nodes shows up as purple and I'm not sure how to make it tap itself to operate how it did in the Sub-VI.
Thanks in advance,
Matt

Answer 1

TeknoAXE wrote:
...The inside of the VI is an orchestration of sequences and loops that allows user full control through one control loop that cycles through until the user selects a desired function, for which the loop terminates and performs the function.  After the function is complete, if the user has not pressed "stop", another loop brings the program back to the control loop.
Well, a tight polling loop is typically not a good design. have you tried the event structure instead?
TeknoAXE wrote:
The problem, I've found, is that I don't know how to send signals to the Sub-VI from the connected controls at a constant rate without throwing it into a loop itself, which doesn't work because, of course, the sub-vi runs on it's own set of loops and there will be no iteration increment until the program inside the sub-vi terminates.
You can wire control references to the subVI and then poll the state of the controls on the toplevel VI via value properties.
TeknoAXE wrote:
Or, if the VI and it's inputs are left on it's own and I try to write values to the controls of the inputs, I can definitely change button positions, but, looking at the signal flows, no signal will be sent from the connected controls to the sub-vi.
Of course you need to call the subVI from a parallel loop (for example) so other parts of the code don't get blocked.
TeknoAXE wrote:
A second problem is that, due to my use of a program button that latches when pressed, I'm having a tough time trying to manipulate it will local variables or property nodes.  Because of the way it functions, the "value" property nodes shows up as purple and I'm not sure how to make it tap itself to operate how it did in the Sub-VI.
Latch booleans are not compatible with locals and value properties. A latch action boolean turns true until it is read by the code. If you were allowed to read (and reset it) it from multiple locations and via multiple mechanisms, you would get completely unpredictable code. You can always use switch action booleans and simulate latch action as needed using e.g. local variables.
It is difficult to give more specific comments without seeing the code. What are the subVIs doing? Are they interactive too?
If you don't mind attach your code and we will give more specific advice.
LabVIEW Champion . Do more with less code and in less time .