micrologix 1200 C series Modbus configs

Hi,
I've got a ML 1200 C series with only 1 port and would like to connect to our DCS via Modbus. Since there's only one port, I've decided to employ a 1761-NET-AIC+ to provide for extra ports for Modbus and programming. Problem now is how to get PLC configured for Modbus. I can change the channel from DF1 Full Duplex to Modbus RTU Slave but then I won't have any port for programming. How will I get my modbus configurations in the PLC referenced to RS485 port on AIC+???