WMS like barcode scan

I want to use barcode scan just like PDA device on werhouse managment system. This means scan barcode from a product and than enter the quantity in the field.
For example, I scan a barcode on a stack of 12 pcs and enter 12 pcs (meaning 12 pcs loaded). Problem is, next time when I scan same barcode I cannot enter 12 pcs again in the same field and get automatic sum 24 pcs, 36 and so on but I only can manually insert total result.
Is there a formula that can make this happen or another way to achieve this?

One option is to create a new record with each scan. Then you can use SUM as the summary function for the quantity.

The summary function shows the sum for only the records displayed. On the computer, you can see totals for each barcode by grouping records by barcode.

Unfortunately, the mobile app does not support grouping records. However, you can see totals for an individual barcode by filtering the view for the specific barcode you want. You do have to “pull down” on the records in the mobile app to view the value of the summary function.