Boolean subtraction and Arduino flashing (LabVIEW 2018 32-bit)

[ekwol]

Hello all, this is my first post here so I apologize if anything is amiss with it. My name is Emily and I am a work study for a college where my job is to help design LabVIEW programs to help my boss educate students regarding electrical circuits and how they work. I'm currently working on a 3-bit Boolean adder/subtractor that's meant to mimic exactly how it would work in a circuit. Another feature of the program is that it should be able to send and receive signals from an Arduino Uno to light up 7-segment LED displays and show the output number when the switches on a breadboard are pressed in various combinations.

Here are the problems I am having.

I isolated the part of the program that does the adding and subtracting so that it's not doing anything with the Arduino for testing. So far the addition works, and the subtraction works when the difference is a positive number, but when the difference is negative it gives bogus results.

The other problem I am having is that it seems that nearly every time I run the full program to test it, I get an error for my Arduino Uno that won't resolve until I use the LINX Firmware tool to re-flash the firmware. Then it works again for a run or two and then the same problem again. I need to know why this is happening and how to fix it.

Thank you so much for taking the time to review this issue, and I wish you all well.

[psuedonym]

About 17 minutes into this Youtube video https://www.youtube.com/watch?v=sJXTo3EZoxM

is a good example of substracting a larger number from a smaller number in binary.