Only the MicroLogix 1100 has a built-in ethernet port, so you will need a 1761-NET-ENI DF-1 to Ethenet/IP converter. Connect it to the serial port of the ML1200 with a 1761-CBL-AM00 cable; the NET-ENI comes with a configuration utility that enables you to configure both the serial port and the ehternet I.P. address of the device.