There are two widespread protocols of use concerning the operation of vending machines: the MDB protocol, issued by the NAMA (See MDB Protocol. Muti-Drop Bus/Internal Communication Protocol. MDB/ICP. NAMA (National Automatic Merchandising Association). Version 3.0, 26 Mar. 2003), which consists of a voluntary standard with a high acceptance level, and which regulates the communication between the machine controller and the different peripherals coexisting with it, such as coin mechanisms, bill validators, and peripherals which do not use cash, such as credit card readers (“cashless devices”). The remaining one is the DEX/UCS protocol, issued by EVA (See EVA-DTS Protocol. Data Transfer Standard. EVA (European Vending Association). Version 6.0, May 2004). It also consists of a voluntary, comprehensive standard, widely used by vending machines. It defines how the communication should be established between the controller of one of the machines and another device, so that the first one conveys to the second data referred to sales, alarms and diverse types of events. In addition, both NAMA and EVA issue other standard documents which regulate other aspects related to vending machines. This is particularly important since dimensional aspects are thereby standardized. (See EVA-CVS Protocol. Cashless Vending Specification. EVA (European Vending Association), Version 1.2, February 2001.)