The VX 820 terminal (and external PINpad, if equipped) feature a contactless card reader embedded into the touchscreen. In a contactless transaction, the customer taps a contactless card on the screen (thus on 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 9999 means there is no maximum limit.