Welcome to the forum!
Thje problem you sketch is something I have never encountered myself. It does not ring a single bell either. Can you experiment with taking out parts of the process of reading this binary file? Is there some point where the decimal point is recognised again? Could it be a setting in your program that changed the decimal separator from a point to a comma? An OPEN statement may contain the DECIMAL keyword to change the significance of a point and a comma,
Just a few random thoughts.