Research Room

1. The card reader only recognizes the card and not the person who carries it; the card can be used on any card reader, making this a true user pays system.
2. Display the remaining credits, when the credits are used up, the power ceases.
3. Three possible ways to tariff:
   1. Inserting card immediately starts tariff
   2. Tariff while the valve is on
   3. Tariff while the fan is operating