Data from vending machines are acquired by a resident data acquisition unit (DAU) implanted in each vending machine. This unit senses coins in, coins out, products dispensed and door openings, among other activities, and provides a data base which records all of these activities. Each vending machine...http://www.google.es/patents/US4306219?utm_source=gb-gplus-sharePatente US4306219 - Vending machine acquisition system
