DEX is not MDB
DEX can provide audit data without providing the live MDB interface a card reader needs.
Conversion options
Current retrofit catalogs list National 147/148 controller upgrade paths that add MDB/card-reader capability.
Crane National 147 Card Reader Upgrade
A stock National 147 should not be assumed card-reader ready just because it has DEX. Retrofit boards are available to add MDB/card-reader support.