Pass through scenario in SAP PI with no mapping for File to IDoc and Idoc to file scenarios

Hi Experts,

Can i have step by step process in SAP PI for pass through scenario with no mapping in case of file to Idoc and Idoc to file both cases please.

What objects i can skip.

My PI system is 7.3 dual stack.

I have seen below blogs, still its confusing to me.

When and how to create an scenario in SAP PI without mapping objects.

Pass Through Scenario with no Mapping in PI 7.1

Appreciate your help on this.

Regards,

Mohan.