Hi, I use unigui for mobiles for a similar process.
On the screen there is a tunimedit component that has the on exit event (the reader reads the barcode and adds a tab to the end of the string).
in the exit I add the whole process, then and remember this, focus on the input field and then delete the content of the input field, if you do it the other way around, it doesn't work (I don't know why) to enter the next barcode (I use pda zebra with bar reader for this job)