Is it possible to create modbus/opc-ua server/client for simulated PLC?

I am new to PLC and PLC programming and i am trying to learn aspects of PLC's. To exercise on PLC, I am using simulated PLC on ISPSOFT and COMMGR. Recently i found there is a factory simulator called Factory IO and i was told we can connect PLC and Factory IO to manage FactoryIO. To do this modbus or OPC server is required. I found out that kepserverex is best way to go but it is licenced and demo version has 2 hour usage limit. I decided to create my own modbus or OPC(I couldn't decide wihch one to use yet) using node-red but as i figured it out, because the simulated PLC itself works on simulated network, there is no way to acces to node-red based server. It is hard for me to bu y a PLC right now, so what should i do to overcome this problem to continue on my practice? Thank you for your answers