Hi @MaxH,
Maybe you could use the following constraint with the barcode question type as shown in the image below:
In the survey tab of your xlsform:
Reference xlsform:
Barcode 2020 09 10.xlsx (10.0 KB)
My assumption is that maybe you have a barcode allocated for each location. In this case set the constraint for each of those locations as shown in the image above. So in your case you should have 40 barcode acceptable. If a user tries to enter the wrong barcode the system (KoBoCollect android app) should be able to capture but would not allow to proceed further.
You could have the constraint as follows:
.=9789993310464 or .=9788131724293
… and so on. Hope this helps.
Have a great day!
