Enable/Disable barcode gun readings

Hello to all,

Barcode gun reads a barcode into a textbox. Using the barcode, vb.net implement a code.
During implementation I need to block/disable new barcode gun readings.
After finishing the implementation, I need to enable barcode gun readings for new entries.
The barcode gun I am using is a simple one. It just read the barcode value.

Thanks to you for help.