When do I have to use the card’s chip to make a transaction?

Always try to use the card’s chip to make a transaction. The mPOS SDK will handle the rest.
Put the card (chip-up and first) into the chip slot of the card reader until you feel a resistance.
If this does not work, the app will askyou to swipe the card's magnetic stripe through the swipe slot of the card reader.
If your card does not have a chip, you can start trying to swipethe card. If the reader tells you to use the chip, simply put the card in the chip slot (any direction that fits). The reader will ask you to swipe again.