Run&Gun
Veteran
I believe that lens data port is only useful if you use a B4 to PL optical adapter such as the IBE HDx35. Then the B4 lens can plug into that port. In theory there are adapter cables to use a cable adaptor along with the 20-pin connector on a lens like a Fuji Cabrio or the Canon 17-102, but I don't know if this will actually function with the F35 as it was discontinued before these lenses existed.
The lens cable/pigtail on the Canon 17-120 is a standard B4 "ENG Lens" cable. The 20 pin connectors are underneath the grip for zoom controllers, focus controllers, etc. If the lens data port connector of the F35 is the same as on any 2/3" ENG cam, you should just be able to plug the 17-120 directly into it. But you may not need to IF it's like the F55. My 55 provides power, control and communication all directly through the pins in the PL mount. No cables required. But I had to plug into the lens port on the VariLT, because the PL mount only provided power and communication(data), the record trigger had to go through the cable. But it seems like a user should be covered, regardless, as long as the camera has the port.