Prevent typing in a cell, but allow entr from barcode scanner.

Good afternoon.
I have a spreadsheet that I use to validate the length of characters in a barcode label.
The user needs to scan the barcode and then by using data validation it tests whether the correct no of characters are present in the barcode. If not an error message pops up saying the barcode is incorrect.
I wish to prevent the user from entering (typing) anything in the cell manually.
I need to be certain that data is only able to be entered by scanning the barcode. Otherwise they will add or delete characters to bypass the error.
Is this possible ?

how do you automate data to be entered into the cell from the barcode?
is it a function in the Software that scans the barcode for you?

(I believe the scanner is setup emulate a USB keyboard).
At the moment I am using a handheld scanner to manually scan 2 barcodes
Once for the model no (13 Char) and then for the serial no (17 Char).
The data contained in the barcode is entered into a cells a1:b1, a2:b2 and so on.
Column A accepts only 13 char, column B accepts only 17 char .
If the both numbers are correct, a timestamp is added in column C the weeknumber in column D and the user in column E excel then proceeds to the next row.