Push button callback in an active while loop instance within a toggle button callback ?

Hello,

My application requires me to use multiple COM (serial) ports for communicating with various devices in my experiment. To start the acquisition, I have a toggle button that opens all ports and starts reading values from the devices. This button is on a while loop as long as the toggle button value is 1. I also have a few push buttons in my GUI with associated edit boxes where the user enters the value they wish to change, and the "update" push button sends a write signal to the devices.

At the moment, I face the following problems:

- If I define the update code in a callback associated with the push button, the program crashes because the callback function doesn't have information on the fopen(...) commands that were used to open the communication ports. If I define an fopen(...) in the callback, it crashes again because my fclose(...) commands are following the while loop (when the user presses the toggle button again to stop data acquisition).

- If I try to use, within the while loop, a property function such as

if get.pushbuttonValue == 1
         communicate with device and update value...;
end

The above doesn't do anything, because I think the push button value changes to 1 only instantaneously? Not sure.

Q1) Is there a good and easy way to make changes on other callbacks when the while loop (when the toggle button is ON) is running?

Can someone explain this with a simple code?

Thanks K