Payment Technology
MDB 4.3
Term from the vending glossary
Current MDB protocol version (2018) with native cashless support, NFC, and mobile payment. De facto standard in European vending operations.
MDB 4.3 is the Multi-Drop Bus version that allows the payment system to communicate more to the vending machine than simply 'paid' or 'not paid'. Notably, it enables a card terminal to reserve a transaction amount and charge it only after successful product delivery — preventing unnecessary chargebacks when a vend fails.
For retrofit installations, verifying protocol version compatibility is the critical first step. An older machine will accept a modern terminal electrically but won't understand its extended commands — leaving you without exactly the features you purchased the terminal for. Therefore, before any retrofit quotation, inspect the vending machine's control unit first — not merely its price list.