The VX 520 terminal features a contactless card reader embedded behind the display screen. In a contactless transaction, the customer taps a contactless card on the screen (thus onto the embedded contactless reader) instead of swiping or inserting it.
Contactless cards can be tapped on a contactless reader for credit Purchases and Refunds only if the amount is at or below the maximum Contactless Dollar Value (CDV).
To determine the maximum CDV for a card, print the EMV Parameters Report and locate the Contactless Trans Limit parameter under the report's record for the card. A CDV of 999999 means there is no maximum limit.