FPGA returning negative values

[abikutn]

Hello,

 I have a question regarding an FPGA program,

the following attachments show the files and configuration I have been working on. When the laser light falls on the detector , the ADC converts to its values and gives me the output. And it returns positive values.

Everything was working fine and now it seems the opposite. When light falls on the detector it returns negative values and when there is less/no light, I get positive values.

I have no idea. why this is happening. Please advise.

PS : I can provide the program if necessary.

[nathand]

What changed when this started happening?  Did you modify your experiment at all?

In my opinion the most likely situation is that the positive and negative analog inputs got swapped - is that possible?  Are the wires somewhere that someone could have bumped them, and then plugged them back in to make it look like nothing happened but reversed them?