We just upgrade to filemaker 16 thinking we will have better performance on our barcode inventory database..... at the time we scan barcodes in a fast way, fm16 leaves some readings incomplete... for example when scanning 10 same items with product number 802312 in a fast way , we got the first 3 records with 802312 and the next 7 records with 2312 ... filemaker 16 miss the first 2 characters... we had to downgrade to fm 15 .... i would like to know what could be the problem? I have a exit trigger script after each reading, the script contains a refresh portal and a commit, it works fine with filemaker 15

You'll have to provide a lot more information.  How is the scanning done, what hardware is being used?  Any other triggers run during/after the scanning?  What does the trigger script do?

Mac or Windows or iOS or all of these?