What is MDB?

MDB (Multi-Drop Bus) is a standard from the 80’s for connecting peripherals such as bill acceptors, coin dispensers and credit card terminals inside vending machines to the master MDB device, the Vending Machine Controller (VMC): The technology used is robust and time proven, but not compatible with USB, serial or network interfaces. It uses a different electrical interface and 9 bit data. In addition, very quick answers are required, hard to achieve with generic computers. The MDB interfaces presented here solve that problem and allow a very easy and reliable connection between a vending machine with MDB bus interface and computers of all kinds.

Learn more about MDB

MDB Explained
MDB Master
MDB Slave
Logging and Debugging MDB


Qibixx is the leading manufacturer of innovative MDB Interfaces and applications

MDB Master

  • Connect MDB credit card terminal to Raspberry Pi
  • Connect MDB company card reader to PC
  • Build vending machine with Windows, Linux or Mac Computer

MDB Slave

  • Emulate a Cashless device
  • Get EVA-DTS Files from VMC
  • Build a mobile payment solution
  • Build a communications Gateway

MDB Sniffing

  • Analyse the MDB Bus to find issues and problems
  • Get telemetry on sales and payments
  • Analyse MDB traffic to monitor cash and product levels

MDB Products

Check out our product line and see how we implement modern payment systems on vending applications

MDB-USB Interface

The MDB-USB Ultra by Qibixx is the newest improvement on our MDB to USB converter product line. It connects the vending machine controller (VMC) to Multi Drop Bus controlled devices and works driverless on Linux, Mac and Windows.

This product replaced our MDB-USB Plus version.

Like the other versions on the MDB-USB product line, it also features Master and Slave functions making it possible to fit cashless payment systems to your vending machine or sniffing the MDB Bus to get data and telemetry.

The MDB interface can be configured to work as a Slave or a Master on the MDB bus. This means that the interface can be used to implement custom MDB payment peripherals such as a custom Cashless Payment Devices, or for developing custom Master/VMC (Vending Machine Controller). In addition, the device is also capable of “listening” to all messages that flow in the bus, without interfering, i.e. Sniffing the bus. All these functionalities can be controlled by software running on the host computer.

In addition, there is also the possibility of using the device in “Stand-alone” mode to request payment from a connected cashless device, and activate a relay for a configurable amount of time (e.g. open electronic doors).



  • USB 2.0 Interface;
  • Dual MDB Connectors with Master and Slave functions;
  • 2 Relay Outputs controllable via Auto Mode;
  • USB-A Socket with Power Output, converted from MDB 5V max 500 mA;
  • RS-232 Interface (for special applications*);
  • I/O For Auto Mode

*Note: From different manufacturers, there are different protocols in regards to the formats of the messages sent by the peripheral and how to interpret them. Therefore, it is needed to implement a different logic for each device to connect. If this is your case please talk to us as a special license will be needed.


The MDB Pi Hat Plus is a reliable MDB extension to use with the Raspberry Pi or other devices with a compatible port.
It provides Master, Peripheral/Slave and Sniffing capabilities and its firmware can be updated from the Pi Interface. Separate Master and Peripheral ports allow you to run both functions independently.

  • High level functional interface for cashless device implementations
  • Independent Master and Peripheral interfaces
  • Jumperless configuration and operation
  • Firmware update capable
  • Universal MDB Interface in Pi Hat form factor;
  • Serial and SPI host interface capabilities;
  • Precise, time-stamped sniffing from MDB bus;
  • High-level, easy to implement serial interface protocol;

MDB Toolchest by Qibixx

MDB Toolchest

The MDB Toolchest is a Java-based Software Application which serves as an invaluable tool for diagnosing, simulating and testing MDB Peripherals or VMC’s.

The Software can accurately catch and decode MDB Communications when paired with the MDB-USB Interface. Sub-millisecond time stamps allow to understand exactly which block had been sent by whom on the MDB Bus.

Various simulation functions allow the MDB Toolchest to impersonate a VMC or a Peripheral for testing purposes.

  • Universal MDB Test, Local or Remote Sniffing and Simulation
  • Written in Java, platform independent
  • MDB Master and MDB Slave simulation support
  • Precise, time-stamped sniffing from the MDB Bus
  • Software can read Bonusdata capture files
  • Able to update the firmware of the MDB-USB Interface (Standard and Plus versions supported)
  • One-time license
  • License tied to the MDB-USB Interface: the software can be used on a unlimited number of computers for file analysis or capture with the licensed hardware
  • Works with MacOS, Windows and Linux



Unigate is a Linux based MDB device with Master, Slave/Peripheral and Sniffing capabilities. It features additional IOs for special applications and can connect via Ethernet to a host or cloud. Due to the embedded, low-power design and high reliability, it is perfect to be used in payment and remote machine monitoring applications. Unigate was designed as a cost effective option to implement custom solutions for MDB Systems.


  • Embedded MDB VMC and Peripheral connectors controlled by the MDB Mini Module;
  • Full-fledged Linux (Openembed/Yocto);
  • 2 Relay outputs;
  • 2 Contact Closure Inputs;
  • 2 USB Ports;
  • Flexa license included, allowing the installation of Qiba/Qibixx applications;
  • Ethernet;
  • RS232 capable;


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