kepware link s7-200 through virtual serial software

as the title,s7-200 send data to hmi computer throught wireless dtu device ,the hmi computer receive by a netcard that had a static ip address links to internet.there is a selection in kepware,when configure it,it had a choice "use ethernet encapsolation",from manual,it said the ethernet encapsulation mode has been designed to provide communications with serial devices connected to terminal servers on Ethernet network,but i don't know how to setup the parameters for that because it needs ip address for everydevice.my device it link by serial devices.so i think i can use virtual serial software to make it.the probleme is when i setup it ,it seems the communication didn't link.anyone had did like this ? and how can i do it?

today,i take a call to siemens engineer,they said that this is an impossible project,i have to add a plc link diectly to a computer,this plc communicate to other plc and receive their data,the hmi software link to it and show all the information.