MDB states describe the different stages of communication between the payment terminal and the VMC (Breeze MDB Utility). Each state represents what the payment system is currently doing — for example, waiting for a card, authorizing a payment, or confirming that a product or service has been delivered.
Authorization First States
| OFF | MDB-USB Interface is not connected to a payment system |
| INIT | reader is disabled and showing the “cash only” screen |
| IDLE | reader displays cashless animation waiting for user to present their card |
| CREDIT | card has been scanned, reader shows the “select a product” screen and waits for the VMC to request the amount to charge the card |
| VEND | reader is waiting for payment authorization |
| RESULT | payment is accepted |
Authorization First Example
| State | Description |
| IDLE | The reader is enabled and is displaying the authorization screen with an animation inviting the user to scan their credit card. When the user scans their card the state changes to CREDIT |
| CREDIT | The reader displays the “select a product” screen and waits for the user to select a product. When a product is selected the state changes to VEND. If a timeout occurs before the user selects a product the transaction is cancelled and the state returns to IDLE |
| VEND | The reader is obtaining authorization for the requested payment. If the payment is authorized the state changes to RESULT. If it fails the transaction is cancelled and the state returns to IDLE |
| RESULT | The payment has been authorized and the reader is waiting for the vending machine to dispense the product. When the product has been dispensed the vending machine sends and END command and the state changes to IDLE. If the vending machine is unable to dispense the product it can send a failure message to cancel the transaction |
Selection First States
| OFF | MDB-USB Interface is not connected to a payment system |
| INIT | reader is disabled and showing the “cash only” screen |
| IDLE | reader displays the product selection screen and waits for VMC to request money |
| VEND | reader is waiting for user to pay |
| RESULT | payment is accepted |
Selection First Example
| State | Description |
| IDLE | The reader is enabled and is displaying the “select a product” screen. When the user selects a product the vending machine requests payment from reader and the state changes to VEND |
| VEND | The reader displays the “authorization” screen and waits for the user to present their card. If the user presents their card and the payment is authorized the state changes to RESULT. If a timeout occurs before the user presents the card or the payment is not authorized or the vending machine cancels the selection the transaction is cancelled and the state returns to IDLE |
| RESULT | The payment has been authorized and the reader is waiting for the vending machine to dispense the product. When the product has been dispensed the vending machine sends and END command and the state changes to IDLE. If the vending machine is unable to dispense the product it can send a failure message to cancel the transaction |