I assume the graphic is just for illustration purpose and has nothing to do with actual hardware you must use?
This is quite straigthforward, unless I am over simplifying it.
This would be a computer running SambaPOS, you create a card account and load money on it. The card can be a anything - plastic card with barcode, RFID card, magnetic swipe card or just a barcode printed on a receipt.
This is another computer running SambaPOS, customer places order and pays with the card. The amount was previously credited to the card account and can be used as payment method. Value can be held on the card for future and topped up as needed.
All computers would be running on same network and from same SambaPOS database.
These tutorials indicate good starting points for this sort of setup:
I assume since you posted this as an Ad, you are looking for someone to set this up for you? I have therefore sent you an email to the email address you posted with my contact details. My company can assist with this setup as a paid service if you wish.