Hi,
the X20IF1091 is not needed, because the bus coupler X20BC00E3 already has a X2X master integrated. Also the bus receiver module X20BR9300 ist not needed if all of the other X20 modules are directly connected behind the bus coupler.
That means, the other X20 modules can be directly connected to this Profinet IO slave.
Bus couplers also need some additional hardware, a base module ( e.g. X20BB80) and a power supply module (e.g. X20PS9400).
For details about the X20 Profinet I/O slave please check the technical data available here:
https://www.br-automation.com/en/products/io-systems/x20-system/bus-controllers/x20bc00e3/
I also recommend to check the X20 system manual to get details about system configuration and detailed information about the modules, the needed additional parts and so on.
It’s available here for download:
https://www.br-automation.com/en/downloads/control-and-io-systems/x20-system/x20-system-users-manual/
Best regards!