It is possible to use a record detail table field as barcode data field. In order to achieve this, you need to execute the following steps:
Add a barcode element to your Connect template via the “Insert Barcode…” option.
By “Data Field” choose the option: “Extra Data” and click on the “OK” button to add the barcode element to your Connect Template
As a result of the previous step, a “Text Script” will be added to your Connect Template. When you double click on the “Text Script” you will be able to select the record detail table field under “Edit Script” > “Field”.
Probably you need to make some changes to the script itself to get the result you want to have. To be able to do that you need to click on the “Expand” button. This will convert your “Text Script” into a regular script.