While using technical terms and poorly written, the question about vending machines actually asks for a device recommendation (although OP couldn't find it). Or at least can be solved using a device recommendation. And the device in question does not break rules I'm aware of.
If you don't know that MDB means Multi-Drop Bus (already suggested an edit) then this question does indeed make little sense.
Edit: I asked this question in part to flag it, in part because it shows that what might be a regular question for one person can be impossible to understand for another. Even within our rules.