Kepserverse to dh485 through netaic

I have an installation of 4 ml1200's and a PC running Kepware's OPC Server and am having problems with the communication between the PLC's and the server. I have 1761netaics for each ml and they are talking nicely to each other. I can talk rs232 DF1 directly to my mls and the server works great, but when I plug the server into the netaic, the server start logging errors that the Kepware Tech Support guru said were framing errors. I have tried adjusting multiple things around this connection. Also, I am using a usb to serial port converter from Black Box and all port speeds are the same on each device. I just don't have a clue where to go from here. I can add the data movement to one plc and therefore bypass the need for the pc to talk to the 485 network that makes comms to all plcs dependent on the single unit, and I would rather not.
Thanks for any help
Aaron

there is networking optain in the Df1 protocal after networking the four plc using Net-AIC you should use 1770-KF3 module to convert the DH485 to DF1

Note:-
Net-AIC is not a protocal convertor,