Hi Everyone, I am using Labview 2009. I want to change the value of a variable using both Knob or Keypad. So I downloaded a multi-rotational Knob and Keypad VIs which suits my requirements from the forum. Both the VIs are running inside a WHILE loop. Since I would be continously updating the variable I will run my main VIs which houses these both the VIs also in a WHILE Loop. Problem is that while loop inside a while loop 😞 I couldnt run my main VI because of this issue. I tried in 2ways 1. Including them as sub-VIs in my main VI but as the both VIs contains some other variables inside the inner while loop Labview pops up error as sub-VIs wont work 😞 2. I also tried copy paste the both VIs as it is in my main VIs but could only end up in heap of errors. How to deal with this issue of nested while loops? Please guide me. Regards, Manoj

You are making a dataflow mistake. The outer loop can only spin if all code in it has completed. The event structure cannot complete because the inner while loop does not complete, and if the inner while loop completes, the loop cannot spin because the event structure stalls. You can only go to the next iteration once both have completed, starting the mess all over. All you need to do in incorporate ALL code inside the event structure. Attached is a simple draft (LV 9.0), modify as needed. See if it makes sense to you. (there are probably minor bugs)

LabVIEW

multiple input and nested while loop problem

Solved!

@altenbach wrote:

Mark, he needs LabVIEW 2009.

(yours is not that different to mine right above)

You posted as I was completing mine. The only real difference is that I do it completely as a number while yours uses a string. The string is actually less complicated but as you say they are similar.

Here is the LV 2009 version.

Mark Yedinak
Certified LabVIEW Architect
LabVIEW Champion

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