Question: how to import udt in tia portal?
Answer: Go to the Simatic S7-PCT (Port Configuration Tool). ... 
Under your IO Controller, click on the Slot of your IO Link Master.
Go to the "Addresses" tab.
Click on "All Ports"
Click on "Create PLC data type sorce file"
Then choose the name for the *.udt that you want to export to TIA Portal and save it.