About MDB Converter (Multi Drop Bus)
Start with the MDB Protocol
Are you tired of using outdated communication protocols in your vending machines? Do you want to take advantage of advanced payment methods and increase efficiency? Look no further than MDB Converter.
The MDB protocol, or Multi Drop Bus, is the industry standard for communication between payment systems and vending machines. It allows for the efficient exchange of data and the integration of advanced payment methods, leading to increased convenience for customers and higher sales for vending machine operators.
But how do you get started with the MDB protocol? That's where MDB Converter comes in. Our easy-to-use tool allows you to quickly and easily convert your vending machines to the MDB protocol, saving you time and hassle. Plus, our comprehensive support and training resources ensure that you have all the tools you need to succeed.
Years ago, we at Abrantix set out to create a cashless vending solution for a client. Back then, we did not know MDB (Multi Drop Bus) and its pitfalls. We had initially planned to implement the whole solution without special-purpose hardware, just in software. After we had created a software-based MDB implementation, we quickly realized that this would not work. We had to come up with dedicated hardware that takes care of the proprietary MDB features like the 9-bit format and the timing windows. I have shared some of our experiences from this learning process here. As a result of this process, our MDB converter product range was created. Our goal was to enable other people, so that they do not have to go through the same process.
MDB Converter Overview
The MDB Converter products by Abrantix make it easy to integrate with MDB vending machines. The converters take care of the MDB specific 9-bit format and timing constraints and simply forward the MDB payload to any RS232 capable device using a proprietary serial protocol (called CP) as described in the SDK documentation. You can find a list of all product editions here.
Each MDB converter can be used as MDB Master (VMC), or as MDB Cashless Peripherals (except for older product editions). We are working on a Coin Changer implementation at the moment and also have clients that use the converter as Comms Gateway. However, these modes are not officially supported.
Depending on the Product Edition, the converters support the following connection options:
- MDB Converter 3 and MDB Converter 4 (Multi Drop Bus)
- USB (with built-in USB to serial adapter)
- RS232 (serial) Low Voltage TTL
- RaspberryPi GIO (s. Raspberry Pi Pinout)
USB Connection Option
The USB connection option is based on a built-in USB to Serial adapter. When plugging in the USB to the PC, the MDB Converter 3 and MDB Converter 4 will show up as serial port. We use FTDI chips as USB to serial adapters. FTDI drivers are available for many operating systems and are pre-installed on many operating systems.
Low Voltage TTL Connection Option
Looking for an Arduino MDB shield? The LV-TTL I/O connection option bypasses the standard RS232 interface and allows to communicate directly to the MDB Converter 3 or MDB Converter 4 micro processor. This allows an easy connection to existing and popular Embedded PCs and Controller boards.
MDB Converter 3 vs MDB Converter 4
MDB Converter 4 is our latest product and is compatible with the MDB Converter 3 in regards to its behavior and APIs. However, the hardware sockets for the USB and serial connectivity options differ and are not the same.
MDB Converter 3
- Micro USB
- Molex Serial Socket
MDB Converter 4
- USB Type B
- Header 2.54mm 2×5 male
MDB Converter 3 will be phased out in 2021.
Raspberry Pi Integration
You can find more information about the MDB2Pi on Pinout.
RTC (Real Time Clock) [MDB2Pi only]
The MDB2Pi contains an RTC. Real Time Clock capability is achieved through the use of a SuperCapacitor (no battery required).
We do not sell a housing for the MDB2Pi. However, you can download a 3D drawing of our housing on thingiverse. This way, you can print your own housings. Of course you can modify the drawings to suit your needs.
Freely Definable MDB Payload and Behavior
The converters use a proprietary serial protocol called CP (Control Protocol) to talk to your application. This protocol only frames the MDB payload and does not put constraints on the MDB messages or behavior. This means that the converters do not implement MDB behavior themselves, which gives you the full control over the messages and behavior.
You can therefore send any MDB data to the bus or implement any MDB behavior you would like. This helped us, for example, with testing, where we implemented different test cases with invalid MDB payloads or strange behavior of the master or slave component.
An exception to this is an Auto-ACKing feature that simplifies the timing behavior. More about this can be found in the manual.
We provide an SDK that contains a sample implementation of a master and a cashless device. The SDK is in C# and also contains the manual and CP specification. For more information, please visit MDB Converter SDK.
5V Output [MDB Converter 3 only]
The converters offer to drive external hardware directly from the MDB Bus with stabilized 5V power @ 1A (up to 5W). Thus there’s no need to deal with the inconvenient MDB Power specifications.