I have just bought this barcode scanner.
After enabling MSI code reading, the scan always transmits one digit that is not part of the code.For example the codebar is 2719219 but the scan will transmit 27192194
How can I make the scanner ignore this last digit!
The 'ARM 32-bit Cortex Scanner' has practically nothing to do with ARM. They probably used an ARM processor inside it but that's about it. There's been a few queries here about that product so I just looked it up on the web and got a video of it being unboxed at www.youtube.com/watch and the box says NEEWER on it so I would guess they made it, and I see Amazon had a hand-held scanner for sale by them. That is a Chinese company and possibly they just took the first string they saw for the English name. It seems to have quite positive reviews but be currently unavailable. So I would suggest you try neewer.com they don't have a current product like this but it might come under support.
That last digit is a checkdigit, I guess you would be expected to check the check digit is okay for the barcode system used and discard it yourself if you want to, in your case I would guess it uses https://en.wikipedia.org/wiki/Luhn_algorithm