soony11 is correct.
However, it is also possible to connect both profibus slaves and one or more HMI panels to the same Profibus port.
Advantages with connecting the HMI to the Profibus port:
The HMI can update faster if the Profibus runs at 1.5M or 12M.
Longer distances than 50 m. can be reached.
Disadvantages with connecting the HMI to the Profibus port:
The update of the slaves will be much slower. The socalled Token Rotation time will be increased by appoximately a factor 10.
If you dont need long distances between PLC and HMI, then the simplest is to connect the HMI to the MPI port.