Invalid Endpoint Error

Strictly speaking, CX-Programmer is a software that programs an OMRON PLC (you do not "transfer the value from Cx-programmer")

And since you are using OMRON PLC, there is no real need to pay lots of money for Kepware. You can use node-red-contrib-omron-fins for many of the OMRON PLCs and skip OPC altogether. Is that an option?