MDB, or Multi Drop Bus, is a standard protocol used in vending machines and other self-service kiosks to allow for communication between the payment system and the vending machine or kiosk. It allows for the exchange of data such as the selection of products, the acceptance of payment, and the dispense of products.
One of the main problems that MDB solves is the need for a standardized communication protocol between payment systems and vending machines. Before the adoption of MDB, each vending machine manufacturer used their own proprietary protocol, which made it difficult for payment system providers to integrate with multiple vending machine brands. MDB provides a common language that can be used by all parties, making it easier for payment systems to work with a wide range of vending machines. MDB also allows for the integration of advanced payment methods, such as credit card readers and mobile payment systems, into vending machines. This increases the convenience for customers and can lead to increased sales for vending machine operators.
Overall, the use of MDB in the vending industry has helped to standardize communication between payment systems and vending machines, making it easier for payment system providers to enter the market and for vending machine operators to accept a wider range of payment methods.
Restrictions of the MDB Protocol
One issue that can arise with the MDB protocol is the need for precise timing of the communication between the payment system and the vending machine. The MDB protocol requires that the payment system and vending machine maintain a strict timing relationship in order to properly exchange data. If the timing is not correct, it can result in communication errors and the transaction failing. Another issue that can arise with the MDB protocol is the limited number of available commands. The protocol only defines a small number of commands, which can limit the flexibility of the system. For example, it may not be possible to add new features or functionality to the vending machine if there are no available commands to support them.
The devices communicate in a single-master, multiple-slave configuration using the MDB protocol which is based on 9-bit, implemented as an 8-bit data value with an additional mode bit. The mode bit differentiates between ADDRESS and DATA bytes. The master sends messages containing one address byte and a variable number of data bytes. The bus "slave devices" listen for an address, and if it matches their address that slave device will process the message and respond to the master.
The MDB-Converter handles the 9-bit data format and makes sure timing is correct.
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