The problem is that those same IOs are not available in the TIA Portal software to assign tags and I can't find a way to establish a communication with the robot controller. I know this isn't a Siemens forum but I was hoping somebody else had succeded in doing this.
The alterative that Kuka suggested was using OPC or other protocol but it's a paid option I don't have.
Siemens HMI are designed to be used with Siemens PLC. I don't think there is a way to connect it directly with other profinet IO devices.