* U - query current coin balance. - replies with CXXXXX
* GXXXXX - give change, XXXXX is the amount of the cost of the item hence change
* is the current value in the coin mech - XXXXX
* U - query current coin balance. - replies with CXXXXX
* GXXXXX - give change, XXXXX is the amount of the cost of the item hence change
* is the current value in the coin mech - XXXXX