Some specific Protection & Security settings are required to establish connection between Factory I/O and Siemens S7-1200 or S7-1500 PLCs.
Open the PLC properties, navigate to the Protection & Security section of the General tab and:
- enable "Permit access with PUT/GET communication from remote partner " under “Connection mechanisms”
- set protection access level as " HMI access " or higher (Read access or Full access)
You can also refer to a step-by-step guide on how to connect Factory I/O to S7-1200 / S7-1500 PLC.