If you look for a simple soft PLC to start with PLC programming with FACTORY I/O, SoMachine Basic from Schneider Electric could be an interesting possibility. SoMachine Basic is free, easy to use and it enables to program M221 PLC in SFC and LD. It integrates a free soft PLC which is Modbus TCP server. So, it can easily be connected with FACTORY I/O by using the driver Modbus TCP client.
SoMachine Basic can be downloaded here :