From the PC's Internet Protocol Version 4 Properties, uncheck "Obtain an IP address automatically" option
and set an arbitrary IP adress that does not duplicate with the address of FX5-CPU module.
Also, if the subnet mask is 255.255.255.0, the first three values (first - third octets) must match the FX5-CPU module's IP address.
*The default IP address of FX5-CPU module is 192.168.3.250 and 255.255.255.0 for subnet mask.
As well, the security softwares (antivirus software) may be blocking the Ethernet communication.
Check if communication is enabled by temporarily disabling the security software or by authorizing communication through the security software settings.