Need help with MDB protocol for Vending Machine

I have some problems with a Vending Machine and understanding of the MDB protocol. I am developing a cashless device and it have some wired behaviors on some Vending machines. I want someone that have done work with MDB protocol on Vending Machines and done cashless device using a computer. I use VS2017 and C# and UWP, but programming ins not needed. Its pure understanding of MDB thats needed.