The debugger and the barcode scanner feature both share the same serial port.

We have a customer who is getting 800004FF errors that trace back to the execution of a memory dump command. The most conceivable possibility is that the customer has a barcode scanner that is somehow sending characters strings that place the port in debug mode and then execute commands.

This change protects the port from barcodes or barcode scanner communication that may, by chance, contain character strings that place the port in debug mode and allow subsequent communication to be interpreted as debug commands.