We have heard this question a few times recently..."can you use a keyboard or monitor mounted MSR and a pinpad with shift4 simultaneously on the same machine?" the answer is NO!
the pinpad is setup in the shift4 utg configuration. once you choose credit cards in retail pro it will give you the same window as you get in ppm or credit pro asking to swipe a card. the difference is that you have to click AUTHORIZE first, and that will send the signal to the pinpad to prompt for a card swipe, then the pin#. so even if you swipe the card before you click authorize (as we do with ppm and credit pro) this number is not recognized and gets overwritten when you click authorize and it sends a signal to the pinpad or signature capture unit.
BOTTOM LINE: choose one or the other, you cannot have both.