The MAXQ622 functions as a USB->UART->HART->UART->USB interface on the evkit. That is its only function. Any actual HART device such as Master, or Field Device etc, would also require both a Link Layer stack, and application code; neither of which is in this code. The function of the MAXQ622 is just for the PC to interface with the evkit board. The MAXQ622 is not running a HART stack.